Get on a Regular Eating Schedule
"I recommend eating six times per day and eating about every three hours," says Nancy Farrell, a dietitian in Fredericksburg, VA. "A snack is 100 to 200 calories, and a meal starts at 500 calories."
Make sure that your snacks are small enough that you'll be able to eat again at your next mealtime.
"Stay away from snacks that are going to fill you up too much," Larson says. "If you're having a smoothie, for example, make it small, like 8 ounces. Not 12 to 16 ounces like we see at smoothie shops."
Choose Low-Volume, High-Calorie Foods
Eat foods that pack a lot of calories -- and nutrients of course -- into a small space. Dietitians call these "calorie-dense." That way you can get the calories you need without filling up too fast.
Some choices that can get the job done:
Nuts. They're high in fiber and protein and have about 150 to 200 calories per ounce. Seeds, such as sunflower and pumpkin, also cram a lot of calories into a few bites. They make a great snack. Sprinkle them on salads, oatmeal, soup, and anywhere else you can.
Nut butters. A tablespoon of peanut butter has about 100 calories. You can also try a spread that's made from almonds.
Dried fruit. You can get 147 calories from an ounce of banana chips. Don't forget raisins, prunes, craisins, dates, and figs, too. Snack on them and toss them into salads and cereal.
Fresh, dense fruits. Some good choices are mangos and avocados.
A medium-sized mango has 130 calories. Avocados can have more than 300 calories, depending on size and type.
"I incorporated a lot of avocados and other healthy fats into my diet when I was trying to gain weight," says Amber Dumler, a museum specialist in Washington, D.C. Already petite, she lost about 12 pounds when she was breastfeeding her first child. She struggled to put the weight back on and keep it on.