How to Calculate the Thermic Effect of Food

We use caloric energy to chew, swallow and digest food. This requires energy, which we get through the food we're eating. This energy expenditure is called the thermic effect. Some foods, like celery and tomatoes, require more calories to process than the food provides. Fats require little energy at all. Calculating the thermic effect of the foods you eat can help you control your weight 1.

Determine the amount of calories for the food you are consuming. Add ten percent of the total calories to compute the average thermic effect. Approximately ten percent of our overall calories are used to process and digest foods. This means if you eat 2,000 calories in a day, about 200 calories would used for digestion.

Categorize the food on your plate, such as "fruits and vegetables," "fat," or "protein." Fish, nuts, legumes and tofu are protein. Vegetables would include green, fibrous and leafy items such as lettuce and celery. Cream, butter and fast foods would fall into the fat category.

Calculate the thermic effect of specific food groups. Factor just three percent for fats. Fats tend to be high in calories and have a low thermic effect. If you ingest 1,000 calories of fat, only thirty calories would be needed for digestion. Compute about a 20 percent thermal effect for fruits and vegetables 1. Fruit high in sugar will have a lower index, but fibrous and leafy green vegetables or fibrous fruit require a lot of energy to burn. Factor a 30 percent thermic effect for protein, which has the highest thermal effect because it takes the most energy to digest 1.