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% water. Half a grapefruit has just 64 calories. Raw, fresh carrots are about 88% 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 various meats, or foods with added fats are higher in calories than are their leaner or lower fat counterparts.