The thermic effect of food refers to the amount of energy used by your body to digest, absorb and dispose of the food you ingest. Consider this the operating cost of working your digestive system; one of the few costs in life you may be happy to pay. You burn off some of the calories you consume in order to digest and eliminate the food.
The overall thermic effect of food is estimated to be, on average, about 10 percent of your overall calories, according to WorldFitnessNetwork.com. If you consume 2,000 calories over the course of the day, about 10 percent, or about 200 calories, will be expended on digesting, absorbing, metabolizing and eliminating that food.
Types of Food
Different types of food require different amounts of energy to process, according to WorldFitnessNetwork.com. Fats have a thermic effect of about 3 percent. If you consume 100 fat calories, only 3 calories will be spent digesting the fat. Fibrous vegetables and fruit have a thermic effect of about 20 percent, while proteins have a thermic effect of about 30 percent. If you eat 300 protein calories, you'll burn off 90 calories digesting the protein.
The number of calories you expend in digestion depends on your body composition. Those with greater muscle mass burn off more calories digesting food than those who have more fat, according to ShapeSense.com.