I'm Gary Taubes, science writer and author of "Sweet Little Lies" about the sugar industry -- AMA

Mr .Taubes,

Here are several studies that refute the central hypothesis you present in your books, relating to Metabolic Advantage. Most of which supporting the "Calories in / Calories out" method of weight loss. Faced with such (peer-reviewed) evidence, do you feel that your hypothesis still holds up, or would you like to concede that it needs revision?

The Studies:

Several metabolic ward studies have shown that there is no difference in weight loss when protein intake was held constant.¹

1. Metabolic effects of isoenergetic nutrient exchange over 24 hours in relation to obesity in women.² No large differences in energy expenditure between the two diets (LFHC/HFLC) or between the groups (lean, obese, post-obese). LFHC participants showed higher thermogenic effect.

2. Energy-intake restriction and diet-composition effects on energy expenditure in men.. Men fed at maintanence for 2wks, 4wks at 50% of maintanence, 1 wk at maintanence at either 40% or 20% fat. Weight decreased from 96.6 to 91.5kg, bf 30.4% to 27.7%. There were no significant differences in 24-h EE or energy requirements per unit body weight due to diet composition or weight loss.

3. Nutrient balance in humans: effects of diet composition.. 3 Men, 5 Women ate HCLF / HFLC for 7 days each. 6 were studied for an additional week at a 45%fat diet. Diet composition did not affect total daily energy expenditure but did affect daily nutrient oxidation by rapidly shifting substrate oxidation to more closely reflect the composition of the diet.

4. Nutrient balance and energy expenditure during ad libitum feeding of high-fat and high-carbohydrate diets in humans.. 11 lean 10 obese subjects were fed HCLF / HFLC diets for 1wk each with unlimited energy intake. Subjects on the HF diet had HIGHER intake than on the HC diet, but energy expenditure was not different.

5. Substrate oxidation and energy expenditure in athletes and nonathletes consuming isoenergetic high- and low-fat diets.

6. Regulation of macronutrient balance in healthy young and older men.. Cross-sectional diet study in which male participants were randomly assigned to a diet: 30%F/55%C, 60%F/25%C, 15%F,70%C. Energy expenditure did not vary across diets or between groups, Macronutrient Oxidation were not significantly different.

7. The effect of protein intake on 24-h energy expenditure during energy restriction.. Cross-over study where caloric intake was either high protein (mixed-diet) or low-protein (and either HF or HC). Highprotein had lower EE decline than other two though weightloss was similar across all three. [Highprotein is good]

8. Effects of dietary fat and carbohydrate exchange on human energy metabolism.. Low fat (10%), mixed (30%) and high-fat (50%) diets were observed over three days, calculating RMR, thermogenesis and EE over 3 days. Lowfat showed higher fat oxidation, suggesting it preferable to low carb for fat loss.

9. Energy expenditure in humans: effects of dietary fat and carbohydrate.. ** 14 non-diabetic subjects / 6 T2 Diabetics had their TDEE measured while on either high fat, high carb diets at 'maintanence.' Expenditures were the same between diets/groups.**

10. Failure to increase lipid oxidation in response to increasing dietary fat content in formerly obese women.^2. Carb / Fat EE was measured in formerly obese individuals and a control group. Only fat intake was modified. No differences observed in low/med fat groups as far as macro balances. High fat, however formerly obese women failed to increase ratio of fat to carbohydrate oxidation appropriately.

11. Energy intake required to maintain body weight is not affected by wide variation in diet composition.. liquid diets were fed to 16 subjects with varying fat content (15%-85%) with a constant 15% protein. No significant variation in energy need observed

12. Weight-loss with low or high carbohydrate diet?. 68 patients were followed for 12 weeks in which subjects followed either a low (25%) or high (45%) carb diet. Weight loss was similar between groups, as was loss of adipose.

13. Effect of high protein vs high carbohydrate intake on insulin sensitivity, body weight, hemoglobin A1c, and blood pressure in patients with type 2 diabetes mellitus.. 12 subjects followed either high carb or high protein hypocaloric diets for 8 weeks. High carb showed a decrease in hemoglobin A1c, as well as increase insulin sensitivity. No observable change between groups on libid levels

For the non-scientific people who want some explanation about all this stuff:

• Is a calorie a calorie?

To continue the parade of literature showing no winner in the carbs v. fat battle royale:

1. Long Term Effects of Energy-Restricted Diets Differing in Glycemic Load on Metabolic Adaptation and Body Composition. Randomized trial of either High Glycemic or Low Glycemic diets administered for 6 months, then self-administered for 6 months at 30% caloric restriction. TEE, RMR, FFM were measured three times through the study. No significant changes in TDEE or RMR between groups, however, LG group DID show more weight loss in those individuals that lost >5% (i.e. low carb lost more in that sub-group, but not in those who were <5% in weight loss.)

2. Long-term effects of 2 energy-restricted diets differing in glycemic load on dietary adherence, body composition, and metabolism in CALERIE: a 1-y randomized controlled trial.

3. Efficacy and safety of low-carbohydrate diets: a systematic review.

4. Popular Diets: A Scientific Review

5. Effects of 4 weight-loss diets differing in fat, protein, and carbohydrate on fat mass, lean mass, visceral adipose tissue, and hepatic fat: results from the POUNDS LOST trial.

6. In type 2 diabetes, randomisation to advice to follow a low-carbohydrate diet transiently improves glycaemic control compared with advice to follow a low-fat diet producing a similar weight loss.

7. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates.

8. Similar weight loss with low- or high-carbohydrate diets.

9. Energy intake required to maintain body weight is not affected by wide variation in diet composition.

10. Effect of energy restriction, weight loss, and diet composition on plasma lipids and glucose in patients with type 2 diabetes.

11. Effects of moderate variations in macronutrient composition on weight loss and reduction in cardiovascular disease risk in obese, insulin-resistant adults.

12. Atkins and other low-carbohydrate diets: hoax or an effective tool for weight loss?

13. Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets.

14. Lack of suppression of circulating free fatty acids and hypercholesterolemia during weight loss on a high-fat, low-carbohydrate diet.

15. Low-fat versus low-carbohydrate weight reduction diets: effects on weight loss, insulin resistance, and cardiovascular risk: a randomized control trial.

16. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial.

17. Long-term effects of a very-low-carbohydrate weight loss diet compared with an isocaloric low-fat diet after 12 mo.

18. Weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet: a randomized trial.

19. The effect of a plant-based low-carbohydrate ("Eco-Atkins") diet on body weight and blood lipid concentrations in hyperlipidemic subjects.

To come at this problem from the other side, here are three studies showing no difference in weight gain when the ratio of carbs:fat is manipulated:

1. Fat and carbohydrate overfeeding in humans: different effects on energy storage.³

2. Macronutrient disposal during controlled overfeeding with glucose, fructose, sucrose, or fat in lean and obese women.

3. Effects of isoenergetic overfeeding of either carbohydrate or fat in young men.

It may also interest you to learn that dietary fat is what is stored as bodily fat, when a caloric excess is consumed. And that for dietary carbohydrates to be stored as fat (which requires conversion through the process called 'de novo lipogenesis' the carbohydrate portion of one's diet alone must approach or exceed one's TDEE.

Lyle's got great read on this subject, but if you prefer a more scientific one I suggest you give this review a gander:

• De novo lipogenesis in humans: metabolic and regulatory aspects.

For a great primer on insulin (with tons of citations) and how it really functions, check out this series:

Insulin…an Undeserved Bad Reputation

The series was summarized quite well in this post.

---

¹ If you're really looking for a metabolic advantage through macronutrient manipulation, you'd be far better off putting your money on protein. There's actually some evidence that higher intake levels do convey a small metabolic advantage.

² These two papers actually found a decreased amount of energy expenditure in the high fat diets.

³ This study found a greater of amount of fat gain in the high fat diet, though weight gain was still similar.

EDIT: "Mr."

EDIT: EDIT: I'm working on a tl;dr that gives an overview of the content of the studies for those who don't have time to read them today (though you should at some point.)

UPDATE: In an effort to make sure I'm giving accurate/correct synopsis of the studies listed for y'all, It's taking me a lot longer as there are a few that I have to re-read. Feel free to gleam over the abstracts, though, as they provide a lot more detail (numbers, etc.) Mr. Taubes however, should be familiar with most of these studies, so he should be able to answer my question.

UPDATE 2: To all the users sending threats of violence via PM - You've been reported. to /r/keto - I've seen two threads now organizing downvote brigades because I'm asking about science. Stop it. It's Taubes, not Ron Paul.

Ok. I obviously don't have time to go through this list, but I can say that we (NuSI and Stuart Buck, the director of research at the Arnold Foundation) recently tried to assess all the relevant studies to see if any of them settled the energy balance vs. carbohydrate hypothesis definitively. Our list of the relevant studies is posted at NuSI along with an assessment of each trial. Here's the URL: http://nusi.wpengine.com/wp-content/uploads/2012/09/Summary-of-Diet-Studies-Condensed.pdf

Our assessment was that not a single one of these trials was even vaguely definitive. Here's the summary of our analysis: http://nusi.org/the-science/review-of-the-literature/#.UJF0qWkiH7E

One way or the other, this is a question that deserves far better experiments and a much higher quality of science to settle. This is what NuSI is planning to do. I'm open to the possibility that I'm dead wrong about this (doubt it, but it's possible) so the argument is let's get the best possible research done and resolve these questions with as little ambiguity as the real world allows. Ideally in ten years we'll have nothing to argue about.

For an idea to be considered rational and scientifically valid, it must be falsifiable -- that is, we must be able to imagine a result which would cause us to revise or abandon the idea. You have taken the position that it is specifically an increase in the consumption of carbohydrates, not merely an increasing energy surplus, which is the driving force behind the rising levels of obesity.

What specific experimental design, outcome or observation would you have to see to make you abandon this position?

That's an interesting question. As you may know, I've recently co-founded, with Dr. Peter Attia, the Nutrition Science Initiative (NuSI.org) to fund and facilitate experimental research that should resolve, we hope, some of these controversies. The problem with this business is that because we have humans as subjects and we live in the real world, ideal studies cannot be done.

One ideal study, for instance, capable of falsifying the carb hypothesis would be to isolate 50,000 identical twins in a setting where we can completely control there diets -- along the lines of the thought experiment I discussed above. Randomize one half of the twin pairs to a standard American diet and one half to a very low carbohydrate diet. Give them no choice but to eat the diets. Say we put each half in a different town and they live there for the rest of their lives and they can only eat the food we supply. Run it out for 20 years and see what happens. If the half eating the low-carb diet is just as fat, diabetic, atherosclerotic, etc. as the half eating the standard American diet, that does a pretty good job of falsifying the hypothesis. If we want to control for calories, we make sure the twins eat the same amount of calories in each town.

Now this is obviously never going to happen. So what can we do in the real world. One of the first studies we want to do will be a rigorous test of the two competing hypotheses -- energy balance vs. carbs/insulin. The idea is similar to what I discussed above in the calories-in/calories-out question and I actually discuss this experimental design in the afterward to the paperback of Good Calories, Bad Calories.

Take as many overweight/obese subjects as we can, isolate them in a metabolic ward, feed them a standard American diet for a month say, get them weight stable and measure their energy expenditure. Then randomize into two groups. Both get exactly the amount of calories that they're expending when weight stable on the SAD. One, though, continues to get the SAD and the other gets a ketogenic/Atkins diet, which can be thought of as a dietary tool to maximally reduce insulin levels. Now run it out for as long as we can before the subjects rebel -- probably two to three months -- measuring energy expenditure regularly, fat mass at the end of the study, and nutrient balance. If they two groups expend the same amount of energy, and have the same fat mass at the end of the two months, that would be a pretty good refutation of the alternative hypothesis. If the low-carb group expends significantly more energy and loses fat in comparison to the SAD group, that would be a pretty good refutation of the conventional energy balance wisdom.

Now here's the problem: in both cases, there would be ways to explain the observations so that they don't actually falsify the less favored hypothesis. This again is a problem with the real world. We'd have to keep doing experiments until eventually even the avid supporters of one hypothesis just decided it was untenable. But as Richard Feynman has said, science isn't about proving or disproving hypotheses, it's about saying which is more or less likely to be true. If we do the right experiments and they're designed correctly -- and this is what NuSI hopes to facilitate -- eventually we'll be able to say for certainty which one of these two hypotheses really is very much more likely to be true. And we'll have to settle for that, until someone thinks of yet another test that should be done.

How about overweight subjects eating diets with identical caloric content but demonstrating varying metabolic rates due to differing macronutrient content?

I did an op-ed to this effect in the New York Times when the study was published. here it is: http://www.nytimes.com/2012/07/01/opinion/sunday/what-really-makes-us-fat.html

[deleted]

Also made my day. thanks.

Mr. Taubes,

Could you clarify your opinion on calories in/out and it's implication for weight loss? I've seen people twist your words a lot of ways on the issue.

One camp says you think calories in/out is solid, however it's lacking in that does not address the behavioral aspect of eating and weight gain. The other says the whole in/out thing is bunk, and any carbs mean weight gain, because insulin.

Where exactly do you stand?

I think calories in/calories out is simply the wrong paradigm to understand obesity and so meaningless. If someone gets fatter, they have to take in more calories than they expend. The same is true when gets kid taller, when people put on muscle instead of fat, etc. Focusing on calories tells you nothing about cause -- why one person puts on fat, another grows taller, one does both, etc.

I've been thinking once again about how to clarify this and I've come up with a couple of ideas. For one, I'll use sugar as the example because that's supposed to be the subject today. Imagine we have a pair of identical twins. Say 18-year-old boys. Every day we measure their energy expenditure and every day we feed them exactly how many calories they expend. So we match calories in to calories out. They get both the same diet with one exception: one gets 300 calories of sugar or HFCS where the other gets 300 calories of a different carbohydrate or of fat. Then we continue this feeding experiment for the next 20 years or so. (Because this is a thought experiment, we don't have to worry about the ethical issues or Institutional Review Boards.)

If you believe obesity is about calorie-in-calories-out and that's the only thing that matters, then both twins are going to end up exactly the same weight with exactly same amount of fat on their body and they're both going to end up expending the same amount of energy. If you believe that the hormonal/metabolic effect of different nutrients is the key factor, then the sugar in the diet of one twin is going to effect his insulin signaling, hepatic (liver) fat production and accumulation, etc, and possibly his fuel partitioning. This twin will end up with more fat, and maybe lower energy expenditure as well. (He or she can't end up weighing more, because we always match calories in to calories out.) The way they partition fuel into storage or oxidation will have changed significantly because of the change in macronutrient composition.

Now if we do the same experiment, but fix the calories in at whatever the twins we're expending at the beginning of the experiment (rather than adjusting it to the expenditure day by day) then the sugar-fed twin is likely to end up fatter as well as heavier because now the partitioning of fuel to fat instead of oxidation can cause this twin to both get heavier and expend less, and so go into positive energy balance.

And if these twins were allowed to eat as much as they wanted, the twin eating the sugar diet might crave more food to compensate for the loss of calories into the fat tissue and the greater need of a larger body.

Finally, imagine we do the same study with 10,000 twins or 100,000 twins. Half get the diet without sugar and half with. The population that gets the sugar, according to this hypothesis, would have more obese twins, more diabetic twins, etc. despite, again, total calories consumed being equal.

Now think of the opposite experiment for weight loss, and you can see why I think calories in/out is meaningless. We could match calories in a pair of obese identical twins and change the macronutrient composition in such away that one twin mobilizes fat from the fat tissue and oxidizes it and the other doesn't. So one twin will lose weight and be in negative energy balance if we allow that to happen and do so on the same number of calories that keeps the other twin as fat as ever and in energy balance.

Does this make sense?

Hello, Mr. Taubes.

I'm simply interested in what you, personally, eat. Any chance you'd give us a rundown on what you've consumed over the past, say, 72 hours?

Thanks in advance!

I've been traveling the last 72 hours so it's not all that meaningful, but I can tell you that I have eggs, sausage and bacon pretty much every morning of my life, and avoid, for the most part, refined grains and starches. My wife's a mostly vegetarian, so we tend to make our own dinners. I'll cook some meat or fish and eat it with a green vegetable that she also eats. As for the kids, well, that's a constant struggle. I don't want to be a food zealot with them, but they do consume significantly less sugar than most of their peers. As for tonight, I'm off duty. We'll probably let them eat three or four pieces of candy and then throw most of the rest out after they go to sleep. I'll direct them to the Snicker's and Reese's peanut butter cups because that's what I'd be eating -- and might have a few small bites -- if I had my choice. While I mostly avoid refined grains, sugar and starches, I'm not completely rigid about it because my weight is fine and I'm healthy. If I found my weight was creeping back up, I'd get a lot more rigid.

Hello Gary, I'd personally like to hear your thoughts on dietary supplements (either in general, or some specific ones that you have any opinions on). I realize this may not be your expertise, but you have enough experience researching diet in general that some motifs could be applied to some nutraceuticals (such as Spirulina, Astragalus, or Maca; which are effectively food products. I edited in hyperlinks to systemic reviews I have personally conducted, and if you hold animal studies with any regard I would mention that Spirulina looks very nice; poor human evidence currently though...). It is just a different side of health preservation, and probably one with just as much (if not more) diluted and screwy evidence as the whole sugar issue.

I work at the website of Examine.com where we compile much information on the topic of supplementation, and many people who come to us are those who are also following ketogenic or paleolithic diets. I haven't followed your work as frequently as I would have liked, but I was wondering if you had any influence on what these people are seeking or whether its just correlated (people interested in health happen to be interested in both of us, independently)

Dietary supplements are outside my area of expertise. I tend to defer here to clinicians and researchers like Steve Phinney and Jeff Volek on what's necessary for a health when carb-restricting. I personally take magnesium supplements because otherwise I tend to cramp up after work-outs, and vitamin D and omega 3 because, well, people I respect and like think they're a good idea. Are the latter two doing me any good? I don't know. That's where randomized controlled trials come in real handy, and I just haven't seen enough in this field to make my confident one way or the other.

What are your thoughts on artificial sweeteners such as Sucralose, Stevia, and Xylitol?

Short answer is I think they're all better than sugar/HFCS and there's not nearly enough data -- randomized controlled trials -- to show whether they are deleterious on their own. The evidence is just poor and the observational studies linking diet sodas to obesity/diabetes are meaningless, because they're, well, just observations and don't say anything about cause and effect. I did a short New York Times Magazine piece on artificial sweeteners about a year ago and concluded that the stevia compounds are probably the best, in that they're natural and have a long history of use. Here's the link: http://query.nytimes.com/gst/fullpage.html?res=9901E0D71E31F931A35753C1A9679D8B63 That said, last time I had a Diet Coke I got a headache the likes of which I can't remember having and so haven't touched the stuff since and that was about four years ago.

This is me.

Where do you come down on the Paleo movement?

I'm obviously a big fan as I think the paleo movement will go along way to getting the conventional wisdom changed. There are some tremendously smart people pushing the Paleo movement and they've raised issues of mechanisms that are intriguing and that go far beyond what I've discussed in my books. I'm hoping that one role of NuSI will be to help elucidate and test these mechanistic questions as well.

I see articles here and there calling Alzheimer's "type three diabetes". Do you think that's a statement with merit, or would you call it hyperbole?

That Alzheimer's associates with diabetes and obesity suggests there's something to it, and there's good evidence that insulin and insulin resistance are involved in the disease state. I discuss that science (and get some of it wrong) in Good Calories, Bad Calories. Researchers I respect do go for the type three diabetes notion, but I'd say it's still preliminary so bordering on hyperbole. As for silverhydra's comment below, the primary Alzheimer's researchers tend to all have their different opinions on causal factors in the disease state, even down to the roles played by amyloid beta and tau tangles. One advantage a journalist in this business is the ability to speak to everyone in the field, or all the major players, and try to make some sense about how the evidence supports the different biases. Whether this is enough to compensate for the obvious lack of expertise or training that the journalist brings to the issue (whether me or Mark Bittman or Gina Kolata or any other) is always an open question and a matter of opinion. If we always had to defer to the authority of primary researchers, then we'd better hope the primary researchers are doing a better job in Alzheimer's research than they've done in, say, nutrition and obesity.

What is worse for you 100 sugar coated duck sized horses or 1 sugar coated horse sized duck?

Can I give this question to my seven-year-old and get back to you? I like it. I think Monty Python would have liked it. But I still think it needs his intellect to work on it more than mine.

Hi Gary,

How do you explain the fact so many people have had such a huge success with a low carb diet, yet it is still such a hotly debated topic?

I can't think of another single diet where you read story after story of not only massive weight loss but so many other positive effects such as increased energy, increased libido, better mood, the slow down or reversal of auto-immune diseases and many other "non-scale victories". These testimonials are not coming from "critics" with something to sell like you'd find on a web page for a diet pill, but real people on discussion forums like Reddit. It's a diet people find easy to stick with because you can still eat good food, and more importantly you can eat when you're hungry.

If you want to see what I mean about the countless success stories, visit /r/keto and sort it by top for the month or the year. It's like we're using science to say "Woah, this doesn't work!" yet many people who do it see real results.

This is a huge question. I think one problem is that we live in a world where we pay a lot of attention to this literature. Most MDs and researchers do not, and so they still see this as a fringe movement. The people they have been taught to respect see it as a fringe movement, and so it goes. I've recently been reading a great book on cognitive dissonance -- "Mistakes Were Made but Not By Me." I highly recommend it as a means, if nothing else, to understand what it might take to overcome the cognitive dissonance in the medical research and public health communities (assuming, of course, that we're right and that the studies NuSI is going to fund and that NIH is already funding don't refute our beliefs entirely).

No question. I just wanted to say that I've read your work, and cut off refined sugars and flour almost completely about 10 months ago, while increasing my leafy greens, fat, and protein intake. I'm down about 65 pounds, 295 from almost 360, and I've never had better health. I'm still losing, and I have a way to go.

I feel like you've steered me in a direction that will enrich and extend my life for many years to come. Thank you for your research and straight-forward approach to a complicated problem. I can only hope you recieve more attention and accolade for the work you do.

Before/After

Thanks. Made my day, as are all the good questions.

Hi Gary,

Once someone has done metabolic damage, is there any way to ever recover, or are the pancreatic beta cells permanently destroyed?

I'm 32 and seem to have some insulin resistance issues. Fasting glucose 103, HbA1C 5.5. Post prandial ranges are usually ~ 110 for low carb meals, 120-130 for medium carb meals, and 140-150 for high carb meals. My doctor claims I'm just a "little high but fine", but I suspect these are pre-diabetic numbers.

I can easily keep my blood sugar down by eating low carb/low sugar, but I'd ideally like to be able to cheat more often if I can increase my insulin sensitivity.

I'm already lifting heavy 3x a week, but that doesn't seem to be helping much.

I think of us can return to metabolic health and some of us can't, and how long it takes will differ vastly between individuals as well. The only way to find out is to self-experiment.

In the Michael Pollan IAMA, there was a comment by him along the lines of "but the world can't support everyone eating meat" when YOU came up. Thats the strongest argument in favor of ChinaStudy/MostlyPlants thinking - right? If that is true, I don't know why that group doesn't lead with their strongest argument.

Personally, I'm now Primal Blueprint (having tried to infer a diet from GCBC, and modifying that to match WhyWeGetFat's advice). It's working well for me. Except when I drink diet sodas (a hard addiction to break). I have to think like I process Citric Acid like a calorific carb, in order to stay strong.

You don't get enough credit IMO (hence my username).

One argument I've been making over and over again is that this isn't about getting everyone to eat meat. We know that there are populations that eat carb-rich diets and don't eat a lot of animal products. This is about getting people to understand that refined grains and sugars are the causes of the chronic diseases that are so common in western societies (assuming, again, that this is correct) and that any diet can be healthier if refined grains and sugars are minimized. If that message gets across -- that it's the carbohydrate content of the diet we should worry about, not the fat -- we might get back to the place where our children or grandchildren can all eat mostly plants, as Michael Pollan would say, and be perfectly healthy.

What are your thoughts on ketosis? We have a strong group here in /r/keto that follow a ketogenic diet for weight loss. Weight loss aside, do you feel ketogenic dieting can offer benefits to your average healthy-weight any individual?

I obviously think ketogenic diets are healthful and that for many Americans they may be the only dietary intervention that will return them to metabolic health. A more important question to me is how much benefit can individuals get from going low-carb, compared to going all the way to a ketogenic diet? For instance, I doubt I'm in ketosis and have never measured, but I'm still 20 pounds lighter than I was back in my carb days.

Hello Mr. Taubes. In your article "Sweet Little Lies" you talk a lot about the history of the sugar lobby, especially one report that was stacked with sugar industry lobbyists and came to the conclusion that sugar was regarded GRAS (Generally Regarded As Safe). I have a few questions about this.

1. You claim that there was plenty of evidence at the time that sugar should NOT be labelled as GRAS. Do you think that it should not be? As in, it is toxic enough to be banned as an added substance in our food?

2. On a related note, do you think it would be realistic at this point to partially or completely ban sugar?

3. What do you think about mayor Bloomberg's large-size soda ban in NYC?

4. If government intervention/regulation is not the answer, what is? Education?

The GRAS review was fascinating because there was indeed plenty of evidence suggesting that sugar was not safe, but the question to some extent was whether it was "generally recognized as safe", which it was. What amazes me about all this is that there was no mechanism for these GRAS reviews to say, "hey, this is a tricky issue, we need more research done and will postpone our decision until we have unambiguous evidence." Instead, they just gave sugar a pass because evidence was not definitive and most experts were obsessed with dietary fat.

As for banning sugar, I can't see that ever happening and I'm not sure it would be a good idea in any case (see, alcohol and prohibition and the war on drugs for possible unintended consequences). What I can see is the country getting to a place, as it has with cigarettes, where the huge majority of the population understands the dangers of partaking and so restricts consumption significantly and the food industry gets on board by taking sugar out of products, or reducing greatly the amount, and then advertising it as such.

And, yes, I'm a big fan of education as a potential answer.

What will you be giving out to kids tonight?

Reese's. I'm looking the other way. Sometimes sacrifices have to be made.

Mr. Taubes,

There seems to be a claim that one of the reasons why carbohydrates should be controlled for adults is that it causes higher levels of IGF-1 which spur the growth of cancer cells. However, IGF-1 is also needed growth for children, would you recommend children to eat a proper amount of carbohydrates instead of out-right avoiding it? Other than avoiding sugar, and refined grains, what are the best sources of carbohydrates for growing children?

Excellent question. I often wonder if keeping my kids away from sugar will also mean they won't grow as tall as their peer group, because of this IGF-1 issue. It's one reason why I'm not more strict than I am. But there's no reason to restrict all carbs if your kids don't have a weight problem. Keeping sugar consumption low and the more obvious processed, refined grains seems like a reasonable compromise.

Hi Gary, big fan of your work- I've purchased and given out a couple copies of Why We Get Fat.

I dropped 45 lbs in only a few months after switching to a low carb (ketogenic) diet, heavily influenced by your work, and it was a life changer for me. I am no longer in ketosis, but do not keep anything containing grains or added sugar in my fridge.

Thanks for doing this! I did have a few questions I would be delighted if you'd answer, below. I know I wrote down a lot, even if you only lightly touch on them or reference your answers to other's I'd be incredibly happy.

• In your book, you push that the total number of carbohydrates in diet was the strongest prediction of weight loss. What is your view on the glycemic index? For example, sweet potatoes vs white Idaho potatoes. If I consume 1000 calories in sweet potatoes as opposed to 1000 calories in a regular, white potato, will there be any difference in terms of predicted weight loss in your view?

• What is your view on alcohol and weight loss? (Carb free drinks like Scotch)

• Is Ketosis a desirable state, or would you recommend most people aim for the minimum number of carbs needed to not be in Ketosis (50-100g is my understanding)?

• While you make it clear that you believe fat intake and obesity have no correlation, what is your view on actual types of fats? Grain-fed farm animals have very different composition of fats than wild animals. Far more omega-6 compared to omega-3, for example. Same for fish; farm raised tilapia has less omega-3 than steak. Do you think there are negative health effects (inflammation?) from changes to modern meat (excluding grass fed)?

• What are your views on vegetable oils such as corn, canola, etc?

• What are your views on aspartame/saccharin/sucralose/stevia/xylitol? If you do use artificial sweeteners, which one would be your choice?

• If in a position to influence government, what policy change would you consider the most important to implement or remove?

• I have to admit, NuSI is kind of nebulous to me. Can you give me a better idea of what kind of data you are trying to collect/how you are going about it? Do you worry about marketing issues due to name overlap with a vegan diet called NuSci (which comes up on Google)?

• Coconut oil, olive oil, or grass fed butter. Pick one.

• Not nutrition related, but curiosity. Dr. Peter Attia identified himself as an ISTJ on his blog (Myers Briggs type/Jungian psychology). Do you, by any chance, know your MBTI type? (INTJ here. I was pegging you for INTP, but entirely guessing.)

• Wanna get a beer sometime?

Ok. As I'm running out of time here, I'll answer your questions as a way of answering a lot at once. Re sweet potatoes vs. white potato, there's a study it would be fun and easy to do. But we'd have to randomize thousands of subjects and run it out for a decade or more to see hard endpoints. Would they really be healthier eating the sweet potatoes. And how about it if it was N hundred calories of sweet potatoes vs. N hundred calories of refined wheat? What would be the difference in morbidity and mortality, weight, etc.? I don't know what the answer is but I wish I did and I wish could do the experiment.

As for alcohol, probably depends on the individual. But I do think that one of the goals in life should be living well, not just living as long as possible.

I don't know ultimately how desirable ketosis is. In the short run, I can see it's benefits and think that for a large proportion of individuals with a large number of disease states, they're obvious. I don't know, though, about the longterm trade-offs of a carb-restricted non-ketotic state vs. ketotic. Again, I hope we can resolve some of this question with the studies NuSI will fund. At the moment, I don't think the evidence exists to go either way with confidence.

Re grain-fed farm animals and fat composition, I'm all for the latter for ethical reasons and I do it myself. I suspect they're healthier and the fat composition is healthier or less deleterious than animals fattened on corn or soy, but I haven't seen enough experimental evidence to know whether this is true, and if it is (which I'm willing to believe) whether it makes a meaningful difference in long-term health. Again, easy studies to design; expensive to do and carry out but it would be nice, from a curiosity perspective, if they existed.

Re vegetable oils, same kind of issue. I stay away from them myself and can easily imaging that they're as bad as people say, but I haven't actually seen the RCT evidence to make me agree with any confidence. When it comes to the observational evidence, I think the signal from refined grains and sugars is so huge, it swamps the vegetable oil signal.

Re policy change, I'd like to see the USDA, NIH, CDC, etc. change their recommendations on obesity and the associated chronic diseases from the current "eat less, exercise more, low fat" variety to recs that advise avoiding refined grains, sugars (and maybe vegetable oils). Before that ever happens, though, far better research will have to be done to establish whether the arguments I make in my books and other like-minded researchers and authors make are true. That's where NuSI comes in and what we hope to make happen.

As for the data NuSI is out to generate, that's a question I can't answer in the three minutes we now have left.

As for the beer, can I get a tequilla, which is my drink of choice on the rare occasions when I have time to indulge?

Mr Taubes,

I've read your books and follow your and others advice about staying low carb. I have gone from being 60-70 pounds overweight to about even.

I have two questions

1. Kids - I have twin boys, they eat no carbs at home except for raw fruits. How do you manage food with your kids and how do you handle food while at school

2. Quitting Carbs - I was a 4 years smoker and quit cold turkey. I've found it much harder to quit carbs. It's like quitting smoking when everybody smokes and thinks you're crazy for not wanting to smoke anymore. How do you handle third party events at houses etc. Do you bring your own food, eat prior and fast while there, pick and choose like an outcast, or just eat what they serve for that meal?

Great to hear about your success. I, too, was a smoker and in many ways it is easier to quit cigarettes. When you do, your friends tend to help out. With carbs, that's not the case. But I tend to eat what I'm given at a friend's house or a dinner party and eat the carbs in moderation or just leave them on my plate. One advantage of being low-carb (for me, and it shows up in the RCTs as well) is that I'm not as hungry as I used to be and so can skip a meal if necessary. I'd rather pick at my plate at a dinner party and then wait to get home to eat what I consider a healthier meal, then have the host or hostess go out of their way to cook me something low-carb as though I was a member of some odd religious sect.

When I was in college, I decided to write my minor thesis on the history of sugar candy. Research was much tougher than I thought. It felt like the candy industry was trying to hide so much. Did you run into this during your research, and how did you overcome stalling tactics?

I've been disappointed as well by the historical record on sugar candy, but I don't know if it's evidence of industry forethought and stalling. If we were choosing to study, say, the tire industry, we might be just as disappointed.

How has the sugar industry ("Big Sugar?") played a role in the USDA's legislation of what can and cannot be bought with foods stamps?

I'm thinking specifically of the connection between the ability to buy SODA with SNAP benefits (legislated and regulated by the USDA) and the USDA's interests in the sugar industry.... Are there "sugar lobbyists?" Or, are sugar interests so overlapping with those of companies like Coca Cola that Coke does the bidding of sugar companies? Thank you!

In answer to your question, I don't know yet, but I bet that if Cristin Couzens, my collaborator doesn't, she will soon.

Do you think Big Sugar will face the same inquries and penalties that were imposed on Big Tobacco?

There's a fundamental difference here that I will think change the way this plays out. With tobacco, the evidence was damning and, as I understand it, the tobacco industry tried to cover it up and make it go away. With sugar, the evidence was suggestive and the sugar industry just tried to make sure that the research to either exonerate sugar or convict it would never be done. They also worked and still work to assure that no consensus will ever be achieved. So ethically it's a different issue and it is legally as well. But now I'm stepping outside what little expertise I arguably have.

Thanks for the AMA! Could you please offer your perspective on sugar addiction? In many of my health and nutrition classes, professors speak about how sugar is the most addicting substance we encounter daily. Even more than caffeine. Are these claims founded?

I find the science not as compelling as I would like, and I find it fascinating that so few research groups have studied this. As a parent, I have little doubt that sugar is addicting and plays havoc with the brains of children. Or at least my children. As an ex-smoker and someone who has a sweet tooth, I also think it's quite obviously addictive.

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Thanks for asking. Go to the NuSI site and look under "Get Involved" and you'll find a link for contacting us. We're still working hard to get NuSI up and functioning and don't really know yet what kind of help we'll need, but we take all offers of help seriously. We're keeping a database of volunteers and at some point in the near future we'll be figuring out how to get everyone to work getting these ideas taken seriously.

How big a factor is genetics? Each population has a bell curve of weight distribution for males and females. Is the obesity problem a shift of the peak of the bell curve, or just the creation of a long tail?

I think the obesity curve is both a shift of the bell curve and a creation of a deeper long tail. As for genetics, I think it plays a huge role, but I think the role is in the tolerance to the carbohydrate content of the diet. Then there are epigenetic factors that are playing roles and maybe gut microbiota factors, that can be influenced by diet or genetics as well.

Dear Gary,

Any developments in the debate between the insulin hypothesis of obesity and the food reward hypothesis of obesity? Could it be that they aren't mutually exclusive, and that food reward theory is positing a plausible psychological/behavioral factor in the development of obesity whereas the insulin hypothesis is positing a more fundamental physiological one?

Also, can you comment on the relationship between leptin and insulin, and the numerous animal models indicating that leptin resistance might be the ultimate cause of insulin resistance, rather than the more intuitive conclusion that it is the over-consumption of carbohydrate?

Re food reward, I just don't find it a meaningful hypothesis, as I've written in my blog. As for leptin, I think it plays an important role and I'll bet (takers?) that it responds to the carbohydrate content of the diet, just as insulin does. Whether leptin is leading insulin is an interesting question. I doubt it, but I could be wrong. And I do think, as I've argued, that obesity can be understood, just as type 2 diabetes can, as an insulin signaling issue. Adding leptin to it might inform the understanding, but I don't know whether it's necessary. Now I'm off to a late lunch. Thanks everybody, gt

Hi, Gary!

There is some research being done by Lustig et al. that aims to settle, or at least help find answers to, some of the controversies surrounding sugar. He seems to be actively attempting the dietary research that you and others claim has been so lacking in the world of nutrition science. Apparently they're now doing things like isolating people 24/7 from being able to eat outside the constraints of the experiment, thus eliminating many of the confounding variables related to diet research.

What if it turns out you are wrong, or at least it is confirmed that things like saturated fats are actually bad for you and that sugar/fat/protein don't matter as much as total calories when it comes to weight loss?

If it turns out that I'm wrong, I'll have to admit it and move on -- maybe get a job selling shoes (I did that in high school for a few months). The key is making sure the experiments are done correctly and as i've noted in earlier questions, this is a tricky business. The problem with feeding of studies of humans as you describe -- and as our non-profit NuSI hopes to fund -- is that they can only be kept up for short periods of time, before money and the subjects' patience runs out. So with sugar, for instance, you end up doing studies for a few months and hoping that what you can learn in a few months will inform you correctly about effects that may take years, or decades or even generations to manifest themselves. This again leaves a lot of room for holding on to beloved hypotheses -- maybe rightly, maybe wrongly. It's what makes science so challenging.

Mr Taubes,

Why do you think that many of the low carb bloggers seem to have a difficult time in keeping off the weight. Jimmy Moore is one that comes to mind. I also noticed that in pictures of this years low carb cruise many of the speakers were noticeably overweight. Any thoughts on that?

Thank you

You always have to ask yourself, first, how much these people would weigh if they weren't low carb? I was speaking in CT a few days ago (the day before Sandy) and one of the folks in the audience -- a man who I would guess was in his 60s -- said he had lost 170 pounds on a carb-restricted diet. He was still probably 50 to 70 pounds overweight. He referred to himself as "still morbidly obese" albeit far less obese than he had been in the past. In his case, he considered the restriction of carbohydrates a life saving choice. So which do you pay attention to -- the 170 pounds lost, or the 70 pounds that never went away?

Does honey have fewer negative effects on the body than processed sugar?

Interesting question. If we could consume honey as quickly and easily as we could processed sugar it might have similar effects and it might not because the viscosity might slow down the digestion and so ameliorate the effects on liver metabolism, insulin secretion and sensitivity, etc. (Assuming, of course, that processed sugar itself has those effects.) But because of the form honey comes in, it makes it exceedingly difficult to consume in quantity. You can't use it to sweeten cold drinks, for instance, and while people use it in hot tea, it doesn't seem to work in coffee. So one way or the other, are consumption of honey is limited by the form it comes in and this would be one reason why it would always be less harmful than processes sugar (assuming, again, that processed sugar is as harmful as I think it is.)

Would you draw a major distinction between the type of carbohydrate in the diet or simply the quantity of consumption. It seems like populations like the Catawbans Kitavans and Pima actually had reasonably "high carbohydrate" traditional diets, but experienced major diet-related western diseases after switching to a western diet that presumably included sugar and refined grains. Perhaps it's not just carbohydrate in general but at least in part the way in which it's consumed or perhaps the source/type?

Edit: spelling of Kitavans, that's what I get for listening to a lot of podcasts/audiobooks and not seeing things in print :-)

Two issues here. What I've been arguing is that it's the type of carbohydrates that make a difference on a population-wide basis --refined carbohydrates (grains) and sugars, in particular. So you add refined grains and sugars to any baseline diet and you end up with obesity, diabetes and the other major chronic diseases that afflict us. But this is a different issue than what an individual has to restrict if they're obese or type 2 diabetic -- metabolically disturbed, in the blogosphere lingo -- to get back to being healthy. For some large proportion of these individuals, giving up virtually all non-green-vegetable carbohydrates may be necessary. (And not juicing the green vegetables, as well.) Then there's another issue: would the refined grains and starches be problematic if not for the sugar in the diet. And I don't know the answer. I suspect not, but I don't have hard evidence on which to nail that suspicion.

Listened to WWGF a few months ago and am now down 20 lbs. Woo hoo! Thanks!

I stumbled across Sugar Busters the other day. Did those guys influence you at all? Were they mostly right?

Sugar Busters was one of the many diet books that came out over the past forty to fifty years advocating low-carb diets. I don't remember the details, but, yes, I think they were mostly right.

So all the economic data shows that quotas and price supports for American sugar farmers have directly led to the creation of and explosive growth of high fructose corn syrup. Ending them would certainly limit HFCS use for more traditional sucrose use, but I have heard in other places that there is really no difference gastronomically between the two. True or false?

I've argued in the past that high fructose corn syrup and sucrose (what we typically mean when we refer to sugar) are effectively identical -- nearly 50-50 combinations of fructose and glucose -- and the research on metabolic effects, short term as it is, has tended to support this. Michael Goran of USC and his colleagues have recently reported that the HFCS used in sodas for instance may be as high as 65 percent fructose, when it should be only 55 percent. And some researchers -- Goran among them -- have argued that the fact that the glucose and fructose in HFCS are not bonded together, as they are in sucrose, also has a meaningful metabolic/hormonal effect in the human body. This could be true, in which case HFCS might be more deleterious than sucrose. The question would then be how much more and is that difference significant? If we replaced all the HFCS consumed in America today with sucrose would it lead to a meaningful reduction in the incidence of obesity and diabetes? (This is what's implied by those manufacturers who advertise "No HFCS" as a selling point on their products and merely replace the HFCS with sucrose or some other fructose-glucose combination.) I doubt it, but it's possible. One of my fears is that by demonizing HFCS, this will be the end result. At the moment my null hypothesis is that sucrose and HFCS are equally deleterious. And I'll accept that HFCS might be marginally worse -- it's possible -- but I don't know if that translates to a meaningful effect in humans.

Mr. Taubes, I've read that when you consume carbs, specifically sugar, along with a high fibre content you can essentially minus the grams of carb from the grams of fibre. I know this slows down the affect the carb has on entering the bloodstream, but doesn't it still affect the liver and therefore the body regardless of the speed it is metabolized in the body? Why is it therefore better to eat sugars when they are accompanied by more fibre?

I would say that the speed of digestion is a key variable here. Think about it this way: if someone applies fifty pounds of pressure to your upper arm by slowly leaning on you over the course of ten minutes, it may be annoying, but it's not going cause much if any harm. If that pressure is applied in a second via a punch, the effect is entirely differently. Far more harmful (far more annoying.) Now say the same thing happens every few hours for days or months or years on end, which situation is likely to lead to chronic damage? The speed at which these nutrients hit the blood stream, the pancreas, the liver, is key.

This thread would be so much better with Lyle McDonald and Alan Aragon...

There would certainly be more expletives. Have they not done a reddit AMA?

Hi Gary, in your experience, what is the best way to convince someone that a high-fat, low-carb lifestyle is healthier than one consisting of "healthy whole grains" and sugar?

Do you have a 30 second elevator pitch?

Yes, tell them to try it for a few months and see what happens. What do they have to lose? If they're not happy with their weight, it's a pitch that can be made in an elevator (assuming, of course, you know the person well enough that they don't slap you in response).