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The Truth About Yo-Yo Dieting (Why It’s Not Your Fault and What You Can Do About It)

Diet, lose, regain. Diet, lose, regain. Sound familiar? If you feel like you’re playing tug of war with the same 5, 10, or even 50 pounds over and over again, you aren’t alone. In fact, only 1 in 6 overweight adults are able to maintain weight loss for more than one year, according to a 2010 study published in the International Journal of Obesity.

For a person who wants to lose weight for their health, the benefits can be significant—from normalizing cholesterol and blood sugar levels to reducing blood pressure and joint pain. But for many, it’s maintaining, not losing weight, that’s the hardest part.

Weight cycling (colloquially known as yo-yo dieting), the phenomenon of repeated episodes of weight loss followed by weight regain, has traditionally been linked to a lack of willpower, but science now knows better. It’s biology, not simply mind over matter, which pushes your body to maintain its highest known weight.

This may seem absolutely crazy—why would your body work against you after you’ve worked so hard to achieve your goal? While science doesn’t fully understand why, it has been hypothesized that the human body doesn’t know the difference between intentional weight loss (i.e. dieting) and starvation. So, every time you lose weight, your body thinks it’s doing you a favor by helping you get back up to your weight before the famine (a.k.a. your diet).

One of the main drivers of weight cycling is that after weight loss, your body’s metabolism drops significantly. For every 10 percent of body weight loss, a person needs to consume 20 percent less calories. And yet, have you ever noticed that after losing weight you actually become hungrier? It’s not your imagination; it’s your hormones. In addition to metabolic slowdown, the body’s hunger and satiety hormones head in an unfavorable direction with weight loss.

A pro-hunger hormone called ghrelin, secreted by your stomach and small intestines, is highest prior to eating and lowest after food consumption. Unfortunately, ghrelin also increases after weight loss, sending a flashing “I’m hungry” signal to your brain. Leptin, one of many satiety (i.e I’m full!) hormones, is also to blame. With weight loss, leptin levels decrease, making it more difficult for your stomach and brain to know when you should be done eating. In 2016, a study published in the journal Obesity linked weight regain in The Biggest Loser contestants to a significant decrease in leptin levels, among other metabolic and hormonal changes.

Increased hunger, combined with a decreased metabolism, is a perfect storm for regain. Your brain wants more calories, but your body now needs less of them.

So, does this mean you should just give up on weight loss and maintenance entirely? Not at all! As a physician who specializes in weight management and nutrition, I am upfront with my patients about all of this data and find it can be empowering. For many people, years of yo-yo dieting can be internalized as personal failure. But by understanding that biology plays a large part in their health and weight history, many people are able to let go of past negative experiences and embrace new tools that effectively prevent weight regain.

Thankfully, science is starting to outsmart the body’s response to weight loss through a combination of environmental, behavioral, and therapeutic interventions.

First, exercise helps. Members from The National Weight Control Registry, an ongoing study of people who have maintained a 30-lb weight loss for at least one year, report engaging in physical activity for an average of one hour per day. Strength training is especially helpful to combat the drop in metabolism that comes with weight loss, as muscle tissue is more metabolically active than fat.

Certain diets can also help. Studies have shown that higher protein, lower carbohydrate diets are best for weight loss maintenance. Protein is not only more filling than carbohydrates, it actually causes your body to burn more calories in the digestion process. Less calories ingested and more calories burned is a win-win in the yo-yo diet struggle.

And finally, medical interventions, from medications to surgery can be extremely effective in maintaining weight loss. A little known fact, even among doctors, is that there are currently 5 FDA approved medications for long-term use for weight loss. These drugs are by no means fast-fixes, and don’t work unless bad eating habits, diet and exercise are all addressed, but they can help take – and keep – weight off.

Although your body’s biology may fight against sustained weight loss, there are new ways to fight back—ways that don’t all depend on your willpower.


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