Simply put, the Thermic Effect refers to the energy used in consuming and digesting food. And in the process of consuming energy, we burn calories. Dietary fat is an example of a food with a low thermic effect. It is processed easily and is quickly stored by the body as body fat. You can see why eating unhealthy fats can lead to weight gain. Not only is it processed quickly, but a gram of fat contains almost twice as much calories as a gram of protein or carbohydrate.

On the other end of the spectrum you have protein. This type of food has a high thermic effect; which is to say that it takes a long time to process it. Carbohydrates, on the other hand, fall somewhere in between fats and proteins. The thermic effect is often computed as 10% of the calories contained in the food consumed.

One of the myths that have arisen because of this is the negative caloric intake of celery. Celery is believed to have a high thermic effect, such that eating one burns more calories than it gives you. Scientific studies, however, have disproved this. Though celery does indeed have a high thermic effect, the human body is a very efficient system. It only needs 10%, as mentioned before, of the caloric intake to process the food.

Still, celery is an example of a low calorie food that can help you diet. It helps keep you full while avoiding too much calorie consumption. Other examples of low calories food include: apples, grapefruit, oranges, broccoli, lettuce, and onions. Basically, most fruit and vegetables.