The keys to energy density and weight loss

Three main factors play a role in what makes food high or low in energy density:

• Water. Fruits and vegetables generally have high water and fiber content, which provide volume and weight but not calories. That's why they're low-energy-dense foods. Grapefruit, for example, is about 90 percent water. Half a grapefruit has just 37 calories. Raw, fresh carrots are about 88 percent water. A medium carrot has only about 25 calories.
• Fiber. High-fiber foods not only provide volume but also take longer to digest, making you feel full longer on fewer calories. Vegetables, fruits and whole grains all contain fiber. Popcorn is a good example of a high-volume, low-calorie whole grain. One cup of air-popped popcorn has about 30 calories.
• Fat. Fat is high in energy density. One pat of butter, for example, contains almost the same number of calories as 2 cups of raw broccoli. Foods that contain fat naturally, such as dairy products and various meats, or foods with added fats are higher in calories than are their leaner or lower fat counterparts.