Without a doubt, overweight (defined by a body mass index greater than or equal to the 85th percentile) and obesity (BMI greater than or equal to the 95th percentile) present clear risks to our health. In particular, the consequences of obesity impact practically every body system, function, and organ. At a very basic level, most adults understand this, and those who do struggle with a variety of diet plans in an effort to lose, and keep off, unwanted body weight. Jessica Migala explains a biological reason why most diets fail:

At the heart of the matter is a little thing called “set point weight,” says Stephan Guyenet, PhD, author of The Hungry Brain. “Body weight is regulated by the brain. If you don’t know that, you’re going to be surprised when your brain and body start fighting back against weight loss,” he says.

This is at the heart of why diets don’t work, says Sandra Aamodt, PhD, (appropriately) the author of Why Diets Make Us Fat. “Whenever your weight changes too much, your brain will intervene to push it back to what it thinks is the correct weight for you. And you might not prefer the same weight your brain prefers. Many of us don’t,” she says.


The body’s metabolic thermostat lies in the brain’s hypothalamus. Hormones released from the body’s fat stores (whose levels are determined by the amount of body fat present) keep things more or less at a steady state. When body fat is lost — on purpose from dieting or inadvertently from illness — less of those hormones are released, and the hypothalamus kicks on to compensate for that loss, conserving that fat as much as possible. As a result, the metabolic rate drops to conserve fat, and hunger rises (to build fat stores back up). With these compensatory mechanisms, the body begins to fight back at the attempt to lose weight. This fight can last a year or more before the metabolic thermostat is reset, leading to an all-out assault on willpower and causing intense food cravings in the meantime:

You can imagine why it’s so hard to lose weight — and even harder to maintain that weight loss. You can do it for a time, but eventually your brain will win out and you’ll stand in your kitchen eating straight from the container of Ben & Jerry’s.

That’s where binging comes in. Whereas you might never have considered polishing off a sleeve of Oreos in the past, your dieting self feels like it’s necessary. “In lab experiments, when scientists want to induce rodents to binge eat, the most reliable method for doing it is to reduce food intake until they’re at a lower weight and then expose them to super tasty food, like Cocoa Puffs or Oreos,” Aamodt explains. She adds that in human research, some studies that look at the brain show that this type of junk food activates reward centers even more fiercely in those who have lost weight. And, she says, animal research may suggest that repeated dieting makes the brain more vulnerable to binging behavior even after the diet is donezo.


In addition to including regular physical activity and adequate sleep to any weight loss plan, fretting about what it is you are eating, rather than how much, is more likely to result in healthy and sustainable weight loss:

Ultimately, you can lower your set point weight so that your body is happy carrying around less fat. He points out that animal and human research suggests that eating a diet of unrefined, lower calorie-density, and simple foods is key. That’s fresh, whole foods enjoyed as nature intended. So rather than ordering fried zucchini and calling it a veggie, you eat that zucchini grilled with a little salt. Instead of eating candied nuts, you eat plain nuts.


Eat real, unrefined (not processed), lower calorie-density, and simple foods. Exercise. Sleep well. That sounds as much like a prescription to maintain, as well as achieve, a healthy weight.

Except for a few medical conditions and medication side effects, overweight and obesity are almost entirely preventable. Prevention starts early in life and can often be challenging. Keeping these parts of our daily lives in balance is what keeps us healthy and happy. Prevention isn’t always easy, but it is our most effective strategy for better health.


Overweight and obesity have been covered extensively on The PediaBlog here.


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