Some people believe it's not necessarily what you eat but when you eat it that matters. Those who practice intermittent fasting (IF) rave about the weight-loss benefits, improved digestion and mood, and ability to crush sugar cravings. Intermittent fasting decreases insulin levels and increases human growth hormone, which optimizes your body's ability to burn fat.
And while there are different ways to practice IF — some do the 16:8 method, where they fast for 16 hours and eat in an eight-hour window, while others do 5:2, where they fast for two days a week and eat normally the other five – many people are confused about what exactly they should eat during their feeding window.
It's true that intermittent fasting gives you a little more freedom to eat what you want. Since you are typically only sitting down to one or two larger meals, you can eat more calories per meal than you would if you ate three or five meals a day. "Technically, there are no diet restrictions with intermittent fasting," explained Kristin Koskinen, RDN. "It's an eating style based on food timing rather than diet composition."
However, there are ways to optimize your intermittent fasting for weight loss. Some people make the mistake of eating as much of whatever they want, including processed junk food, during their feeding window. If you eat in a calorie surplus, especially of empty calories and processed food, it will undo all the benefits of fasting.
"For optimal results with intermittent fasting, it's important to continue to drink plenty of water and eat nutrient-dense foods during the feeding times," Kristen said. "Food should be eaten mindfully and slowly, and without the mindset of getting it while you can or making up what you lost when fasting." If you're looking to eat healthier overall, she recommends starting by first cleaning up your diet before you try IF: replace processed food with whole foods, eat more plant-based, and cut back on refined sugars and sweeteners. With these healthy habits in place, then you can give intermittent fasting a try.
Summer Yule, MS, RDN, agrees that while you technically can eat whatever you want during intermittent fasting, that's not the best way to see results, especially if you are trying to lose weight. She said to eat a balanced diet that includes fruits, vegetables, whole grains, and protein. If weight loss is your goal, make sure you are still eating in a calorie deficit during your feeding window. Not sure how many calories you should eat for weight loss? Use this formula to calculate your ideal daily calorie target.
Before you try intermittent fasting, be sure you talk with your doctor or a registered dietitian, especially if you have diabetes, pre-diabetes, or another chronic condition. Many people swear by the benefits of IF, but it's not for everyone.