A general thumb rule is to aim for 150-250 calories per snack. Remember, snacks should always reflect a good balance between enough calories to satisfy you and not too many to promote unwanted weight gain.

When you snack, you are essentially consuming calories in addition to meal calories, and if you consume more then your body's required daily caloric intake, you might expect to gain weight.

It also helps curb your appetite to prevent overeating at the next meal.