There are many ways to try intermittent fasting but whether it’s good for you or not depends on which method you take. Learn about the touted benefits and risks of fasting, the pros and cons of the approaches, and how to do each one.
Registered dietitians often hear “Tell me what to eat.” Now they might be hearing “Tell me when not to eat.” It’s called intermittent fasting (IF), a dietary approach that involves interspacing planned periods of fasting with regular eating. Proponents say this diet is the key to lasting weight loss, better metabolic health, and a longer life.
The Proposed Health Benefits of Intermittent Fasting
When it comes to weight loss, there are two thoughts behind why IF has the potential to work. The first: “Periods of fasting produce a net calorie deficit, and so you lose weight,” explains Rekha Kumar, MD, a specialist in endocrinology, diabetes, and metabolism at the Comprehensive Weight Control Center at Weill Cornell Medicine and New York-Presbyterian in New York City. The other concept is more complex: This approach may prevent what’s called the “plateau phenomenon” from happening, she says.
You may remember the famous, so-called Biggest Loser study, published in August 2016 in the journal Obesity. The researchers followed up with participants after six years, and despite the initial impressive weight loss, they regained most of the weight, and their metabolic rates had slowed, such that they burned far fewer calories than would have been expected.
Though more research is needed on the safety and effectiveness of IF, one of the touted benefits of this approach is it may prevent this metabolic sputtering. “Most people who try diet and exercise to lose weight tend to fall off the wagon and regain weight. Hormones that promote weight regain, like hunger hormones, are kicked into full gear, and the thought is that IF may be a way to prevent this metabolic adaptation from happening,” says Dr. Kumar. Normal periods of eating in IF “trick” your body into losing weight before the plateau happens.
So, does it actually lead to weight loss? Anecdotal evidence has led proponents of the plan to concur with a resounding yes. “For the people who can adhere to IF, it does work,” says Kumar. But fans of the approach claim there’s so much more to IF than just a lean body. Lori Shemek, PhD, a nutrition and weight loss expert in Dallas and author of How to Fight FATflammation, explains to clients that IF may better their insulin sensitivity (to lower the risk of type 2 diabetes), reduce inflammation, and “boost longevity by bettering the health of your mitochondria (cell powerhouses),” she says.
In one small study published in The American Journal of Clinical Nutrition, obese adults not only lost an average of 12 pounds over eight weeks of IF, but they also lowered their total cholesterol, “bad” LDL cholesterol, and systolic blood pressure. A study published in June 2018 in the journal Nutrition and Healthy Aging found that 12 weeks of IF didn’t affect cholesterol levels, but it did lead to weight loss and decreased systolic blood pressure. That said, it’s important to note that studying human longevity is much more difficult than weight loss. That’s why much of the research that suggests IF promotes a longer life span has been done in animals, including fruit flies, like in a study published in June 2018 in the journal Current Biology.
|Read on: 6 Types of Intermittent Fasting: Which Is Best for You?|