Content warning: fat, diet.
Epistemic status: plausible and interesting.
In Gary Taubes’s latest appearance on EconTalk, he gives an alternate explanation for weight gain. He dismisses Calories In/Calories Out as equivalent to saying “Bill Gates is rich because he made more money than he spent.” – it’s not actually wrong, but it’s not answering the question in any meaningful way. He offers the following explanation for a way that could work. I know enough to know that this explanation is plausible but haven’t looked into the evidence that it actually explains the data.
Insulin is a hormone that signals your cells to take in sugar from the blood stream. Different cells have different insulin sensitivity; I’d guess that this is to give the most important cells first call on sugar, but I’ve never heard anyone else say that. It’s possible for things to get out of whack such that your fat cells (which should really have last call on the sugar) become more sensitive than other cells. So you’re gaining fat even as your more functional cells are on rations. CICO is still technically true, as you’re not expending very many calories, but it’s unfixable by willpower. As long as the different sensitivities exist, you can only raise your calories out by taking in many more calories.
None of that is the speculative part. We can argue about the prevalence and importance, but “cells don’t respond to insulin” is the definition of type 2 diabetes, a thing that definitely happens and is associated with weight gain. Medical science has always assumed the causality started with fat, but it’s never actually proved it. The speculative part is Taubes’s explanation that this mismatch is caused by eating sugar, and his solution. Taube thinks you should get most of your calories in the form of fat, which does not trigger insulin production, so your working cells can get calories before your fat cells gobble them up. I have a few qualms about this.
- Your brain runs on sugar, resorting to protein only in the direst emergencies.
- Why aren’t the fat cells releasing fat later? This is less a qualm than a question, I find it entirely plausible that fat cells reaction to being well fed is not to release fat.
There’s a million weight loss fads (twenty years ago my mom was giving me Lucky Charms because at least it didn’t have fat like ice cream) and the human body is immensely complicated, so even if we knew the mechanism was true I wouldn’t automatically believe his prescriptions were correct. But it does highlight how useless Calories In/Calories out is.
Aceso Under Glass 
The other issue is what is reasonably possible for a person of ordinary willpower to accomplish long enough to do any good long term? The diet I lost 85 pounds on sounded unmanageably strict on paper, but turned out to be impressively easy. Some of the claims of this diet are that it manages cravings well, that appears to be true–and probably the most important part for me. It’s been over a year since I hit my goal weight (after 3 downward revisions) and I’m 5 pound under now. Statistics say I’m still likely to go back to my original weight within 5 years, but the lack of effort to make it this far makes me think I’ll be OK.
> Statistics say I’m still likely to go back to my original weight within 5 years, but the lack of effort to make it this far makes me think I’ll be OK
See my earlier point: https://acesounderglass.com/2017/05/14/an-alternate-explanation-for-dieting-studies/ . I think those statistics may be based on a group selected for their inability to lose weight.
Here’s a book review suggesting some alternatives to both calories in/out and the insulin model:
http://slatestarcodex.com/2017/04/25/book-review-the-hungry-brain/
https://acesounderglass.com/2017/04/25/7427/ , although I view the insulin model as perfectly compatible with the multiple set point model.
No, CICO isn’t useless. The overwhelming majority of difference between people who lose weight and those who don’t is that people who lost weight ate less, and people who didn’t lose weight, didn’t eat less. Yes, there probably are some unusual characteristics of people who participate in diet studies, but the military has used the same model (extra rations if underweight, reduced rations if overweight), and it works for them too. Yes, insulin could be an issue for some, but it’s unlikely to be the biggest cause for most or else we would expect to see a large difference between low-carb and low-fat diets in terms of weight loss, which there isn’t one.
Pagoto, S. L., & Appelhans, B. M. (2013). A call for an end to the diet debates. Jama, 310(7), 687-688.
Okay, but why do they eat less or more?
That’s a behavioral question; not a nutrition question. It’s unreasonable to blame nutrition advice for not answering a question it’s not intended to answer. If that’s the thinking, it would be better to say something like: All this clinical research is a waste of time. We should be studying psychology and neuroscience to figure out how people lose weight. But if insulin were affecting how much people eat, and this were a very large effect, we would still expect to see low-carb dieters lose a lot more weight than low-fat dieters in many studies because the low-carb dieters would be eating a lot less. That’s not what’s happening.
Taubes’ rejection of the CICO model is not controversial among people that have a deep understanding of physiology. It is only controversial among people that have only been taught the CICO model as a kind of nutrition dogma, and have not learned about the alternatives.