4. Serving size control: Frozen food plays a clever trick on us with its packaging. We heat a meal knowing it’s designed for one person’s consumption, and therefore consume the entire thing. Dishes that emphasize carbohydrates and cheeses are among the highest in calories, and are worthwhile to avoid. On the other side of the spectrum, meals that promote low calorie content are probably not giving you much in the way of nutrition, and instead you’re paying for empty space.