This article is an excerpt from the Shortform book guide to "Fast. Feast. Repeat." by Gin Stephens. Shortform has the world's best summaries and analyses of books you should be reading.
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Do any diets actually work? Why does food- or calorie-restrictive dieting not work in the long term?
According to Gin Stephens, the author of Fast. Feast. Repeat., dieting for weight loss doesn’t work in the long term. However, decades of contradictory advice about how and what to eat for weight loss has created immense confusion, a tangle that she calls “diet brain”: When you no longer have any clue how to eat “properly.”
Here’s why dieting doesn’t work in the long term, according to Stephens.
Dieting Is Not a Sustainable Solution
To understand why dieting doesn’t work, you need to understand how the body stores energy. Stephens explains that when we eat, our blood glucose (blood sugar) levels increase. In response, our bodies release insulin, a hormone that stores excess glucose in the liver and muscles as glycogen. If any blood glucose remains after this step, insulin converts it into fat and stores it away. By storing this glucose-based energy, insulin lowers your blood glucose. When your blood sugar runs out and you need energy, the pancreas signals for your liver to release some of its stored glycogen to use as energy.
Stephens explains that diets don’t lower insulin levels enough to deplete your glycogen stores and start burning fat. This is because diets work on the logic of “calories in, calories out”—that is, eat less than you need and you’ll lose weight.
(Shortform note: Fung agrees, and he argues that dieting doesn’t lower insulin levels because it doesn’t address insulin resistance. In short, chronically high insulin levels—such as from constant eating—cause your cells’ insulin receptors to become insulin resistant: They need more stimulation (more insulin) for glucose to enter the cell. Eating less doesn’t solve this because any eating stimulates the release of insulin. The solution, he asserts, is to regularly fast for 24 to 36 hours, since fasting gives your body extended time to break down insulin.)
While dieting or eating less works temporarily, it also causes metabolic adaptation, a scenario wherein your metabolism slows down to deal with perceived starvation. It works like this: When you eat fewer calories than you need to maintain your weight, your body thinks you’re starving. Then, Stephens says, it makes three changes to handle the situation:
- The hunger hormone, ghrelin, increases. This makes you want to eat more.
- The satiety hormone, leptin, decreases. This makes you less satisfied, so you’ll want to stuff yourself.
- Your metabolism slows down. This lowers your energy levels and slows you down, so that you can “survive” until food becomes available again.
Diet for long enough, and your metabolism settles in at that slower pace—that’s the “adaptation” in metabolic adaptation. Then, you’ll need to eat even less to continue losing weight, since you aren’t burning as much energy—creating a downward spiral of hunger and slowing metabolism.
| Dieting Also Poses Psychological Difficulties In Intuitive Eating, Evelyn Tribole and Elyse Resch explain the psychological dimensions of why dieting doesn’t work. As they say, dieting fails because of both your body’s reactions to deprivation and because it creates a downward spiral in your emotional health. The more you try to diet, the more diets inevitably fail you. If you remain unaware that it’s dieting’s fault, not yours, you’ll continually blame yourself and feel wracked with guilt. Bingeing is one symptom of this “diet backlash.” Binging is a psychological condition wherein you fixate excessively on food, feel frequent cravings for “bad” foods, overeat to an extreme level, and lose trust in your ability to eat well. To overcome this, realize that dieting simply doesn’t work. It fails to take into account the power of the hormones that regulate our appetite and weight—and you can’t overcome such hormonal imbalance with willpower. Instead, drop the idea that whether or not you diet “successfully” has any bearing on your character. It isn’t a moral issue, it’s a biological one. The solution is to learn to eat enough (not too much or too little) while trusting yourself to make the right eating choices. |
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- How intermittent fasting can help you lose weight, feel better, fight disease, and live longer
- An explanation of the cutting-edge science that supports fasting
- How to follow a four-week quickstart program to adapt to this new lifestyle
