Why Do Almost All Diets Fail?

A friend asked me recently why almost all diets fail. The most basic answer is that I don’t know. But I do have some possible reasons:

First, we have what is now called a “lipostat” which has a gravitational pull bringing us back to a steady-state weight. As I write and quote in “How Rising Anorexia Can Go Along with Rising Obesity: Both Can Be Caused By Environmental Contaminants”:

In addition to arguing for environmental contaminants contributing to the rise in obesity—and anorexia—the “A Chemical Hunger” series of blog posts is also important in making the case for the powerful influence of a “lipostat.” A lipostat is a fat-regulating mechanism in your body that pulls us strongly toward a particular weight—a weight that can get pushed around by chemicals. Our lipostats invalidate the naive version of “calories in/calories out” that treats calories in and calories out as if they were entirely under our conscious control. One of the reasons this is wrong is fidgeting. Here is the relevant passage from the “Paradoxical Reactions” blog post:

… avoiding food and collecting cookbooks isn’t the lipostat’s only method for controlling body weight. It has a number of other tricks up its sleeve.

Many people burn off extra calories through a behavior called “non-exercise activity thermogenesis” (NEAT). This is basically a fancy term for fidgeting. When a person has consumed more calories than they need, their lipostat can boost calorie expenditure by making them fidget, make small movements, and change posture frequently. It’s largely involuntary, and most people aren’t aware that they’re burning off extra calories in this way. Even so, NEAT can burn off nearly 700 calories per day.

… people with anorexia fidget like crazy. A classic symptom of anorexia is excessive physical activity, even in the most severe stages of the illness. When one group measured fidgeting with a highly accurate shoe-based accelerometer, they found that anorexics fidget almost twice as much as healthy controls.

This kind of fidgeting is the classic response in people whose bodies are fatter than they want to be. In studies where people were overfed until they were 10% heavier than their baseline, NEAT increased dramatically. All of this is strong evidence that people with anorexia have lipostats that mistakenly think they desperately need to lose weight.

For some people, the lipostat is set too low; they are prone to anorexia. For many more people, the lipostat is set too high; they are prone to obesity. There is wide agreement that misregulation of the lipostat has something to do with our modern environment: the type of food available and now customarily eaten, patterns of activity or lack thereof, environmental contaminants, other social or environmental causes. It isn’t easy to change one’s lipostat—after all, for most people it got misregulated gradually over the course of many years, and short of doing something quite dramatic, one could expect it to take a long time to get back on track, even if you knew how. I’ll save the discussion of the dramatic until last. Until then, let me talk as if the lipostat is stuck.

Fortunately, lipostatic gravity doesn’t always win, just as the earth’s gravity still hasn’t brought the moon down. But just as the moon avoids coming down to earth by always staying in motion around the earth, (short of accomplishing the difficult task of getting at the root of lipostatic misregulation) counteracting lipostatic gravity requires a permanent change in behavior. As I write in “Kevin D. Hall and Juen Guo: Why it is So Hard to Lose Weight and So Hard to Keep it Off”: “permanent weight loss requires permanent changes in behavior.”

So, the second reason many diets fail is because many people conceive of a “diet” as something you do for a while to lose weight, in the expectation that the weight will then stay off even after return to the pattern of eating that prevailed before the “diet.” That doesn’t work very well. Go back to the old behavior and you are likely to go back to the old weight.

Third, the way many people do diets, they are quite painful. For one thing, many people try to cut back on calories while still eating high on the insulin index. If you do that, you will be hungry and miserable. The Minnesota starvation experiment proved that. But if you eat low on the insulin index, you will be much, much less hungry physically, and it won’t be so bad. (See “Forget Calorie Counting; It's the Insulin Index, Stupid.”) Exactly how difficult differs from person to person, but it will be much, much less difficult.

To add to the physical misery of cutting back on calories while eating things that keep one’s insulin high, many people ramp up their internal self-criticism when they are on a diet. That makes them even more miserable than the physical discomfort alone would. (I’ve put a set of links on positive mental health at the bottom of this post that are relevant to avoiding this sort of thing.)

Being miserable physically and psychologically is likely to make you feel sorry for yourself. When you are done with your “diet” you might well compensate by eating bad stuff—perhaps even worse things than before you started the diet. And psychological misery might have other more direct hormonal effects on weight—more likely in the direction your lipostat is misregulated than in the opposite direction.

The fourth reason almost all diets “fail” is because people expect an unrealistically high dose-response. Many diets have been shown to bring people’s average weight down by a few pounds. But if people think it is only worth it keeping a new way of eating up if it brings their weight down a lot, then they might well give up.

So, what can work? Fasting. Fasting is a big dose. Done right, it isn’t that painful. (See “Fasting Tips.”) You can modify it to make it easier and it will still work. (See “My Modified Fast.”) It can be done periodically on an ongoing basis. It can be motivated as not just a way to reliably lose weight, but also as something that improves your health quite a bit even if you do little enough that your weight stays about the same.

Evidence is currently rolling in from many experimental trials showing the benefits of fasting. This is one area where I don’t have to make my usual complaint about crucial things being underresearched. Fasting is getting researched a lot these days.

As I prefigured early in this post, fasting might even be able to undo some of the misregulation of your lipostat. In particular, a fair bit of obesity is caused by diabetes and prediabetes. Fasting is a powerful treatment for diabetes and prediabetes. On that, take a look at the books of Jason Fung. (I list Jason Fung’s book The Obesity Code as one of “Five Books That Have Changed My Life.”)

For organized links to other posts on diet and health, see:

Posts on Positive Mental Health and Maintaining One’s Moral Compass: