The foods you eat trigger the metabolic process and require an expenditure of energy to digest, absorb and transport the food’s nutrients to your body’s cells. This overall process of stimulation is known as the thermic effect of food, or TEF. Five to 10 percent of your body’s daily energy requirements go into processing the foods you eat. Not all foods are created equal, and some foods have a higher thermic effect than others.
As a general rule, your body expends more energy, or calories, to process proteins than it does to eat and digest carbohydrates and fats. You’ll burn up to 30 percent of the calories in lean-protein foods just to process them, putting proteins at the top of the list in terms of thermic effect. Of the other two macronutrients, carbohydrates require the next highest expenditure of energy to process. Their thermic effect averages between 15 and 20 percent of the calories in those foods. Most easily digested are fats, which have a thermic effect of only 2 to 3 percent. This means that your net caloric gain from fats averages 97 to 98 percent of their total calories, compared with a net caloric gain of about 70 percent of the calories in lean protein.
Some spices and caffeine tend to prolong and enhance the thermic effect triggered when you consume high-thermic foods. Capsaicin, found in chili peppers and paprika, not only bolsters your metabolic rate, but it also decreases cholesterol absorption and increases the enzymes that metabolize fat, Irby says. Caffeine also gives a temporary lift to the metabolic process.
The thermogenic effect after food is the stimulation of metabolism and therefore increased heat production that occurs from 1 to 3 hours after a meal as a result of the processing of food in the stomach and intestine And the processing of nutrients in the blood and body cells.
the thermogenic value is the energy that body used to digest the food, perform the associated metabolic responses and the storage of food example the harder the food is to digest the harder the thermogenic value of that food.
High Thermogenic foods( aids fat burning)
Omega 3 fatty acids
Low Thermogenic foods ( results in fat storage)
Saturated and Trans fats
Solid foods have higher thermal unique value than liquid foods with the same macro nutrient composition due to the greater energy cost of digestion
example full fruits should be preferred over fruit juices