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.