Avocado

This superfood is packed with good for you nutrients and antioxidants, as well as belly-filling fiber and heart-healthy monounsaturated fats. But if your goal is to lose weight, you'll need to watch your intake. Avocados are high in fat and calorically dense. One serving size is about 1/5 of an avocado, and clocks in at 50 calories, and a single avocado can deliver more than 350 calories. This means that the small bowl of guacamole you enjoy so much is more than a snack its actually getting closer to a whole meal.