It’s not rocket science: Eat less and you’ll lose weight. The problem is, it’s hard to eat less all the time. What if there was a way to eat less sometimes, and still lose weight? Intermittent fasting is a strategy that focuses more on when you eat, and less on what you eat. The rules are simple—don’t eat on certain days or at certain times. There are different ways to do it: The 5:2 diet suggests eating normally 5 days out of the week, but limiting food intake to less than 500 calories 2 days a week. Alternate Day Fasting limits calories every other day. Time-restricted feeding recommends eating all your meals within a 6- to 8-hour window, and fasting for the remaining 16 to 18 hours a day.
For some people, fasting feels easier than cutting and counting calories, and studies show it’s just as effective in helping you lose weight. The major upside is that you may lose mostly fat, unlike normal diets (which restrict calories every day), where you end up losing a combination of fat and muscle. “Fasting for at least 12 hours a day puts you in a magic fat-burning zone, by changing the way your body burns carbohydrate and fat,” says Courtney Peterson, Ph.D., an assistant professor of nutrition sciences at University of Alabama at Birmingham. Celebrities and even athletes swear by this method, and it might be how your friend or coworker (finally! magically!) melted away those 20 pounds.
Fasting has shown numerous other health benefits, too, from slowing aging to lowering your risk for cancer, diabetes, and heart disease. The theory? The same way exercise stresses then strengthens your muscles, fasting stresses your cells, but then allows them to recover and become more resistant to disease. Admittedly, most of the research so far is with animals, but human studies show promise. Plus, compared to paleo, which claims to imitate how our ancestors ate, intermittent fasting actually comes closer. Your body is biologically hardwired to hang onto calories, because it anticipates periods of starvation.
But you also don’t want to become ravenous, distracted from your job, or hyper focused on food. Here’s how to practice intermittent fasting the safe and effective way—and keep your metabolism on its toes.
Breakfast Like a King
Peterson strongly recommends the early time-restricted method, eating all of your calories within 6 to 8 hours. Starting early maximizes the benefits by working with your body’s natural circadian rhythm, not against it. “We found that eating between 8 a.m. and 2 p.m., followed by an 18-hour daily fast, kept appetite levels more even, in comparison to the average American schedule,” says Peterson. “The first half of your day is when your digestion and blood sugar control are much more efficient, so if you’re going to skip a meal, it should be dinner, not breakfast.” Peterson also believes it may be possible to see some of the same benefits without fasting for such long periods. Start with a 9-hour eating window (8 a.m. to 5 p.m.), and work your way down from there, if necessary.
Leave Room for a Social Life
If you follow strict fasting hours during the week, it’s okay to relax on the weekends, and enjoy an evening meal out with friends and family. Fasting improves your metabolic flexibility (your body can be trained to switch more easily between burning carbs and fat), which means you don’t need to be disciplined every day. Researchers believe practicing intermittent fasting for 5 days a week may still result in some benefit—not all, but some. Of course, this doesn’t mean you can binge—the harmful effects of a high sugar, salt, or saturated fat diet won’t miraculously disappear! You still need to choose foods that provide the most nutrition for every mouthful.
Take a Sustainable Approach to Fasting
You can get the health benefits of intermittent fasting without taking it to the extreme. Going hours without eating will cause you to feel hungry at first, but after a few weeks, you’ll adapt to your new schedule. If you’re trying 5:2 or Alternate Day Fasting, avoid missing out on essential nutrients by eating healthy food whether you’re “fasting” or not. And on your low-calorie days, go for lean protein and veggies, which will help you feel fuller. If you’re doing the early time-restricted feeding, it’s important to plan your meals so that you eat enough calories in those 6 hours, or you’ll be starving and miss the point of challenging your metabolism.
If you still find these approaches too extreme, take aspects and apply them to your life in sustainable, achievable ways. Simply keeping dinner light by eating a salad or soup, and avoiding late-night snacking, has been shown to result in weight loss, too. You can get benefits without having to “go on a diet,” and you still get to eat dinner with your family—even if it means eating like a pauper.
Note: Fasting isn’t for everyone, particularly if you’re still growing (under 18 to 20 years old), pregnant, have a history of disordered eating, a chronic disease like diabetes, or are taking certain medications. Always talk to a health professional first.
This article is not intended to substitute for informed medical advice. You should not use this information to diagnose or treat a health problem or condition. Always check with your doctor before changing your diet, altering your sleep habits, taking supplements, or starting a new fitness routine.