Most kids are famished when they get home from school, so who can blame them for wanting a snack to carry them over until dinner?

But with childhood obesity on the rise, you may want to think twice before turning your kids loose in the pantry. Most kids will fill up on snacks, and even healthy fare can pack a lot of calories. Peanut butter on whole grain crackers makes a great snack, but just 2 tablespoons of peanut butter has a whopping 190 calories, so they should be careful how much they eat.

Portion control is one of the keys to healthy eating. So, teach your kids about the relationship between serving sizes and calories. Show them how to use the Nutrition Facts label—found on all prepared foods and drinks—to find these three things:

Serving size—one container isn’t necessarily one serving; measure your food to see how much you’re really eating.

Calories—they’re listed for one serving; 100-200 calories is about right for a snack. To control your calorie intake, always eat pre-measured food from a plate, bowl, or single serving size baggie, rather than straight from the container.

Nutrients—try to get 20 percent or more of protein, fiber, and some essential vitamins and minerals (such as vitamin C and calcium) in a single serving; but limit your intake of saturated fats and sodium to 5 percent or less per serving of food. Strive for 0 trans fat, or trans fatty acids—this harmful fat raises your bad cholesterol (LDL) and lowers your good cholesterol (HDL).

Keep two kinds of snacks in your home—healthy snacks that kids can take without getting your permission—and sugary treats that you should give out in limited quantities. And get creative. Instead of chips and dips, try hummus with low fat, whole grain pitas or tortillas.

For foods that aren’t pre-packaged—nuts, grapes, orange sections, apple slices—prepare individual servings and put them into resealable plastic bags or containers. Keep them in convenient places in the fridge and pantry, so kids can help themselves.

Ed. Note:   This blog is part of a series of nutrition tips from FDA nutrition expert Shirley Blakely, Ph.D., R.D