Whether you need a nibble before hitting the gym or crave an after-dinner treat, go for it: Studies show that snacking can help control your weight and increase your energy. But choose wisely -- the ideal munchies should contain about 250 calories or less and have a mix of carbs (for energy), fat (to satisfy your hunger) and protein (to keep you full), experts say. Here, guilt-free options for every situation.

Before a Workout

"Your body burns carbs for energy," says Lona Sandon, R.D., a professor of nutrition at the University of Texas Southwestern. "If you don't have an immediate source available, you'll feel sluggish during your workout." So have a carb-rich snack a half hour before exercising. Some suggestions:

6 oz. light yogurt with 2 graham crackers (149 calories). Look for a yogurt brand that delivers at least 20 percent of your daily calcium needs. 16 oz. iced caffe latte made with nonfat milk (93 calories). The caffeine will jump-start your workout. 1 cup low-fat cottage cheese with 1 cup light canned peaches (233 calories). Canned fruit is a fiber-rich sweet treat.

When You're Craving Chocolate

"Eat some chocolate!" says Althea Zanecosky, R.D., spokesperson for the American Dietetic Association. Just opt for healthy fixes, such as:

Sugar-free hot cocoa made with 8 oz. nonfat milk (141 calories). It delivers 30 percent of your daily calcium needs. 5 Dove Dark Chocolate Promises (210 calories). Dark chocolate is loaded with antioxidants. 6 oz. fat-free chocolate pudding (100 calories).

When Lunch Is Still Two Hours Away

Go for snacks that are high enough in fiber and water content to fill you up on fewer calories, says Zanecosky:

1 packet flavored instant oatmeal made with water (170 calories). Oatmeal contains soluble fiber (the kind that makes you feel fuller, longer). 1 apple with 1 oz. low-fat string cheese (180 calories). Preportioned cheese keeps you from overnibbling. 6 oz. light yogurt topped with 1 oz. almonds (254 calories). Nuts are filling, thanks to their fiber and healthy fats.

For That 3 PM Slump

Look for snacks with protein and carbs to hold you over until dinner, says Sandon. She recommends:

1 hard-boiled egg on a rye cracker (170 calories). Hard-boiled eggs will last up to five days in the fridge. 1/4 cup hummus with 1 cup bell pepper slices or sugar snap peas (130 calories or less). Chickpeas contain both complex carbs and protein and deliver long-lasting energy. 1/2 English muffin with 1 tbsp. peanut butter (160 calories). The muffin has carbs for energy, and protein-rich peanut butter will keep you energized.

After Dinner

Munch on low-fat foods, which are easy on your stomach (digestion can interfere with sleep). Smart picks:

1 cup whole-grain cereal with 1/2 cup nonfat milk (151 calories). Nighttime noshers who chose cereal as an after-dinner snack lost more weight than those who ate whatever they wanted after dinner, says a recent study. 4 cups air-popped popcorn with 2 tsp. Butter Buds (132 calories). Snacks with irregular shapes, like popcorn, give you the illusion that you're eating more, so you'll feel fuller sooner, say Penn State researchers. 1 cup warmed nonfat milk with cinnamon (86 calories). Milk contains tryptophan, a natural sleep inducer.

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