Thermic effect of food or TEF in shorthand, is the increment in energy

Energy

In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...

 expenditure above resting metabolic rate

Basal metabolic rate

Basal Metabolic Rate , and the closely related resting metabolic rate , is the amount of daily energy expended by humans and other animals at rest. Rest is defined as existing in a neutrally temperate environment while in the post-absorptive state...

 due to the cost of processing food

Food

Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...

 for storage and use. It is one of the components of metabolism

Metabolism

Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...

 along with the resting metabolic rate, and the exercise component. Another term commonly used to describe this component of total metabolism is the specific dynamic action (SDA). A common number used to estimate the magnitude of the thermic effect of food is about 10% of the caloric

Calorie

The calorie is a pre-SI metric unit of energy. It was first defined by Nicolas Clément in 1824 as a unit of heat, entering French and English dictionaries between 1841 and 1867. In most fields its use is archaic, having been replaced by the SI unit of energy, the joule...

 intake of a given time period, though the effect varies substantially for different food components. Dietary fat is very easy to process and has very little thermic effect, while protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 is hard to process and has a much larger thermic effect.

Factors that affect the thermic effect of food

The thermic effect of food is increased by both aerobic

Aerobic exercise

Aerobic exercise is physical exercise of relatively low intensity that depends primarily on the aerobic energy-generating process. Aerobic literally means "living in air", and refers to the use of oxygen to adequately meet energy demands during exercise via aerobic metabolism...

 training of sufficient duration and intensity and by anaerobic

Anaerobic exercise

Anaerobic exercise is exercise intense enough to trigger anaerobic metabolism. It is used by athletes in non-endurance sports to promote strength, speed and power and by body builders to build muscle mass...

 weight training

Weight training

Weight training is a common type of strength training for developing the strength and size of skeletal muscles. It uses the weight force of gravity to oppose the force generated by muscle through concentric or eccentric contraction...

. However, the increase is marginal, amounting to 7-8 cal per hour. The primary determinants of daily TEF are the quantity and composition of the food ingested.

Although some believe that TEF is reduced in obesity, discrepant results and inconsistent research methods have failed to validate such claims.

Types of foods

Raw celery

Celery

Apium graveolens is a plant species in the family Apiaceae commonly known as celery or celeriac , depending on whether the petioles or roots are eaten: celery refers to the former and celeriac to the latter. Apium graveolens grows to 1 m tall...

 and grapefruit

Grapefruit

The grapefruit , is a subtropical citrus tree known for its sour fruit, an 18th-century hybrid first bred in Barbados. When found, it was named the "forbidden fruit"; it has also been misidentified with the pomelo or shaddock , one of the parents of this hybrid, the other being sweet orange The...

are often claimed to have negative caloric balance (requiring more energy to digest than recovered from the food), presumably because the thermic effect is greater than the caloric content due to the high fiber matrix that must be unraveled to access their carbohydrates. However, there has been no research carried out to test this theory and a significant amount of the thermic effect depends on the insulin sensitivity of the individual, with more insulin-sensitive individuals having a significant effect while individuals with increasing resistance have negligible to zero effects.

Australia's Human Nutrition conducted a study on the effect of meal content in lean women's diets on the thermic effect of food and found that the inclusion of an ingredient containing increased soluble fibre and amylose did not reduce spontaneous food intake but rather was associated with higher subsequent energy intakes despite its reduced glycaemic and insulinemic effects.

Measuring TEF

The thermic effect of food should be measured for less than or equal to five hours.

The American Journal of Clinical Nutrition published that TEF lasts beyond 6 hours for the majority of people.

Processed foods and TEF

Research has found that the thermic effect of food contributes to the fact that calories may not all be equal in terms of weight gain. Sadie Barr showed that the consumption of processed foods led to a 50% decrease in postprandial energy expenditure.