Grabbing an apple as a 4 P.M. snack to hold you over? That’s fine. Your all-fruit smoothie or gigantic bowl of melon, on the other hand, isn’t going to work as a stand-alone meal, says Keri Glassman, RD, author of The New You and Improved Diet. Fruit is all carb, which makes your blood sugar spike, then drop—leaving you hungry (and tired) an hour or so later. For a meal or snack that lasts, combine fruit with protein or healthy fat, both of which slow down digestion and prevent that sugar rush. Think: 2 Tbsp of peanut butter for dipping apple slices; 1 cup of yogurt or half an avocado blended into your smoothie; or ½ cup of cottage cheese to top off your bowl of pineapple.