You should eat reasonable snacks when you're losing weight, for two reasons. First, it's best not to let yourself get too hungry or you will be tempted to overeat. So six small meals will be better at keeping you satiated than three large ones. Second, you need to give yourself permission to have snacks. Many people find comfort in knowing they can have that bedtime snack, albeit a small, reasonable one, and that they are still making smart choices for their health.