Specific dynamic action (SDA), also known as thermic effect of food (TEF) or dietary induced thermogenesis (DIT), is the amount of
energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...
expenditure above the
basal metabolic rate
Basal metabolic rate (BMR) is the rate of food energy, energy expenditure per unit time by endotherm, endothermic animals at rest. It is reported in energy units per unit time ranging from watt (joule/second) to ml O2/min or joule per hour per kg b ...
due to the cost of processing
food
Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...
for use and storage.
Heat production by
brown adipose tissue which is activated after consumption of a meal is an additional component of dietary induced thermogenesis. The thermic effect of food is one of the components of
metabolism
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
along with
resting metabolic rate Resting metabolic rate (RMR) is whole-body mammal (and other vertebrate) metabolism during a time period of strict and steady ''resting conditions'' that are defined by a combination of assumptions of physiological homeostasis and biological equili ...
and the
exercise
Exercise is a body activity that enhances or maintains physical fitness and overall health and wellness.
It is performed for various reasons, to aid growth and improve strength, develop muscles and the cardiovascular system, hone athletic ...
component. A commonly used estimate of the thermic effect of food is about 10% of one's
caloric
Caloric is a brand of kitchen appliances, which dates back to 1903.
History
Caloric Corporation began as the Klein Stove Company in Philadelphia in 1890. The Caloric brand was introduced in 1903. It was reorganized in 1946 as the Caloric Stove C ...
intake, though the effect varies substantially for different food components. For example,
dietary fat
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
The term often refers specifically to triglycerides (triple e ...
is very easy to process and has very little thermic effect, while
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
is hard to process and has a much larger thermic effect.
[Christensen, Peter]
"What is the thermic effect of food?"
Retrieved March 28, 2005.
Factors that affect the thermic effect of food
The thermic effect of food is increased by both
aerobic training of sufficient duration and intensity or by
anaerobic weight training
Weight training is a common type of strength training for developing the strength, size of skeletal muscles and maintenance of strength.Keogh, Justin W, and Paul W Winwood. “Report for: The Epidemiology of Injuries Across the Weight-Traini ...
. However, the increase is marginal, amounting to 7-8 calories per hour.
[ The primary determinants of daily TEF are the total caloric content of the meals and the macronutrient composition of the meals ingested. Meal frequency has little to no effect on TEF; assuming total calorie intake for the days are equivalent.
Although some believe that TEF is reduced in obesity, discrepant results and inconsistent research methods have failed to validate such claims.
The mechanism of TEF is unknown.][ TEF has been described as the energy used in the distribution of nutrients and metabolic processes in the liver, but a hepatectomized animal shows no signs of TEF and intravenous injection of amino acids results in an effect equal to that of oral ingestion of the same amino acids.][Chaprapani U. and Satyanaryana. Biochemistry, 4th Ed. Elsevier India, 2013 ]
Types of foods
The thermic effect of food is the energy required for digestion, absorption, and disposal of ingested nutrients. Its magnitude depends on the composition of the food consumed:
* Carbohydrates: 5 to 15% of the energy consumedcelery
Celery (''Apium graveolens'') is a marshland plant in the family Apiaceae that has been cultivated as a vegetable since antiquity. Celery has a long fibrous stalk tapering into leaves. Depending on location and cultivar, either its stalks, lea ...
and grapefruit
The grapefruit (''Citrus'' × ''paradisi'') is a subtropical citrus tree known for its relatively large, sour to semi-sweet, somewhat bitter fruit. The interior flesh is segmented and varies in color from pale yellow to dark pink.
Grapefruit is ...
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 fibre matrix that must be unraveled to access their carbohydrates. However, there has been no research carried out to test this hypothesis 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.[J]
Measuring TEF
The thermic effect of food should be measured for a period of time greater than or equal to five hours.
References
Further reading
*
{{Citric acid cycle enzymes
Metabolism