What would happen if you didn’t eat for 16, 20, even 24 hours? Despite what many fitness buffs have advocated for years, it wouldn’t be the nutrition violation you may think it is. No, your metabolism won’t come to a screeching halt causing weight gain, nor will your body suddenly launch into a catabolic state, tearing down your hard-earned muscle. In fact, surmounting research shows the opposite: that not eating for a determined period of time—known as intermittent fasting—could be one of the most effective strategies for shedding unhealthy body fat, retaining muscle and even extending your life.
But before we go on, let’s be clear: this is not a starvation diet or a meal plan consisting of maple syrup and cayenne concoctions. We’re talking about skipping a few meals, maybe as little as once a week. Intermittent Fasting (IF) is simply a determined period of time when you’re not consuming any calories (water, black coffee and tea are still on the menu). If that’s your idea of crazy, consider this: a 2013 study published in the British Journal of Nutrition found that more women lost weight when using an IF strategy than when they followed daily calorie-restricted diets. What’s more, IF has been shown to improve insulin levels, squash sugar cravings, and ward off disease. Do we have your attention? Keep reading to find why six meals a day may not be your best friend when it comes to burning fat.
WHAT THE IF?
For breakfast lovers and six-small-meal advocates, the whole concept of IF may be tough to swallow, as it challenges everything you thought you knew about solid nutrition. But the science behind occasional meal skipping is pretty sound: After several hours of fasting your body has metabolized excess glucose in the bloodstream—prime time for fat burning.
Enter fat adaptation: a process where your body becomes more efficient at using fat for fuel, which in results in lower insulin levels and reduces your risk of diabetes. “Higher levels of insulin will push your body to use carbohydrates as a fuel source,” says Mike T. Nelson, PhD, member of the American College of Sports Medicine, “lower levels push your body to use fat.”
Biology aside, the more obvious reason why IF can be an affective fat-loss solution is that you’re consuming less food, and therefore fewer calories on fasting days than others, which could result in more than just a trimmer bod. Several studies have suggested that eating less could help people live longer, healthier lives, potentially due to reduced blood pressure and heart rate and lower body fat and cholesterol.
HOW IT’S DONE
Like most nutrition strategies, IF comes in many shapes and sizes. One variation is the “Lean Gains” approach, which consists of a “feeding window” of eight hours or less a day, such as between noon and 8pm. Another strategy is to fast for an entire 24 hours once or twice a week. The latter requires a gradual process starting with skipping one meal the first week, then two meals the next. The method you practice depends on your personal preference and lifestyle, but in order to turn your body into a fat-burning machine, ideally you should be aiming for a fast of at least 16 hours.
If 16 hours without food sounds daunting, think of it this way: when you wake up from an eight-hour slumber, you’re already halfway there. The next step is just moving your breakfast from 8 am, to 10am, and you’ve made it 14 hours, says Nelson, and that’s a good starting point. The following week, go for 16 hours and see how you feel. “If you had never deadlifted before, you wouldn’t put 400 pounds on the bar,” says Nelson. “Approach intermittent fasting in a progressive manner, just like you would with loading in the gym. Forcing yourself to go from six meals a day to 24 hours without eating rarely works well.” Keep in mind that while you could reap serious benefits from a few hours without food, we’re not saying you have to abandon your four-six meals-a-day regime. On non-fasting days, you can return to your regular healthy eating habits.
WHAT’S THE CATCH?
There’s no denying skipping the morning oats you love won’t be easy at first (see “Tips for Success” for more), but hunger pangs should be minimal with a gradual approach to prolonged fasts, and cravings should dissipate within a few weeks as your appetite hormones and glucose levels start to balance out. “Data shows that if you can remove the psychological side of it, there doesn’t seem to be detrimental effects in healthy individuals,” says Nelson. As for negative cognitive side effects, research actually points to evidence of improved brain function as a result of fasts.
All that being said, fasting isn’t for everyone and you should definitely check with your doc before adding IF into your healthy lifestyle. Also, if you are pregnant, have low blood pressure, are currently diabetic, or have had an eating disorder, IF isn’t for you. Most importantly, if you’re perfectly happy with your current nutrition strategy and are getting wicked results, stick with what works for you.