Yogurt contains tons of protein and calcium but very few calories. In order to properly convert the nutrients, your body uses up a lot of energy, which it draws from fat deposits. Even more, the milk bacteria in the yogurt will stimulate your digestion. Avoid falling into the trap of overly sugary and calorie-loaded yogurts though: opt for natural yogurt instead. Just add a few berries and you'll have a wonderfully refreshing pick-me-up.