The Numbers: Calories, BMI, and Portion Sizes

Nutrition can be complicated. How do you know which foods are healthy and what aren't? How much should you eat? What's a healthy portion size? How many calories do you need? Do you weigh just the right amount-or are you underweight or overweight? Keeping track of how much you eat, weigh, and exercise can help you make the right choices. Discover how knowing the numbers-calories, BMI, weight, and more-is a big part of staying fit and healthy.