Negative calorie foods are sometimes publicized as a way to quickly lose weight. These foods are referred to as "negative calorie" because the body burns more calories to consume and digest them than the foods actually contain, thereby contributing less than nothing to your daily caloric intake. Although the term negative calorie is a misnomer because all foods contain some calories, people can lose weight eating these types of foods. Because of its low calorie content, a diet that consists of only negative calorie foods does not provide enough energy or long-term nutrition for the body and is not recommended.
The practice of eating uses energy as food is processed by the body. This is known as the thermic effect of food, which burns calories as a person chews, swallows, digests and metabolizes food. Dr. Joshua Whorley, PhD., of Seattle Central Community College states that foods that are high in protein have a higher thermic effect, while foods high in fat use less energy to digest. Fruits and vegetables fall in between for the amount of energy used for digestion.
Fruits and Vegetables
Fruits that are considered to have negative calories include blueberries; citrus fruits, including oranges and grapefruit; and melon, including watermelon and cantaloupe. Other kinds of fruits that are also considered negative calorie include apples, peaches, grapes, apricots, tangerines, cherries and prunes.
Many vegetables are considered negative calorie because they have a high water content. According to the Fat Free Kitchen, some of these vegetables include lettuce, celery, radishes and cucumbers. Other types of vegetables that are also considered negative calorie include cauliflower, beets, carrots, green beans, spinach and turnips.
Some high protein foods, mostly fish and shellfish, are also considered negative calorie. According to the Fasting.ws website, these include tuna, cod, flounder, trout, shrimp and clams. In order to remain low calorie, they must be prepared without added butter, coatings or sauces.
Eating negative calorie foods can provide some positive nutritional benefits. The American Council on Exercise states that many of the negative calorie fruits contain vitamin C and antioxidants that can protect against cancer and improve the body’s immune system. Many negative calorie foods contain other nutrients such as folic acid, iron and omega-3 fatty acids, as well as fiber. Some examples of these types of foods are artichokes, lentils, egg whites and tuna.
While negative calorie foods are healthy, following a diet that consists of only these foods contributes to weight loss simply because the daily intake of calories is so low. The Ohio State University Extension's "Chow Line" column states that eating only negative calorie foods can contribute to malnutrition and recommends eating a balanced diet of fruits, vegetables, dairy and lean protein. Negative calorie foods are recommended for their health potential, not as a method of weight loss.