Biochemistry · Topic
Specific dynamic action (thermic effect of food) !
After a meal the body burns extra energy to digest, absorb, process and store the nutrients. Protein costs the most.
Updated 2026-11-01
Key facts
- Specific dynamic action (SDA) is the rise in heat production above BMR after eating; on a mixed diet it is about 10 % of the energy eaten.
- It is largest for protein (about 20–30 % of its energy), smaller for carbohydrate (about 5–10 %) and smallest for fat (about 0–3 %). Older textbooks quote 30 %, 5 % and 13 %.
- Main causes: the ATP cost of absorbing nutrients and of storing them (glycogen, fat, protein), of making urea from surplus amino acids and of gluconeogenesis.
- It starts within an hour of eating and can last several hours (about 4–6 hours after a large meal).
- This is why BMR is measured fasting and why about 10 % is added when estimating daily energy needs.
In detail
- 1. Absorption: active transport in the gut (for example the Na⁺-glucose cotransporter, kept running by Na⁺/K⁺-ATPase) uses ATP.
- 2. Protein: surplus amino acids are deaminated; making one urea costs four high-energy phosphate bonds, and turning the carbon skeletons into glucose or fat costs more ATP.
- 3. Carbohydrate: storing glucose as glycogen costs a few per cent of its energy; turning it into fat (lipogenesis) costs much more.
- 4. Fat: dietary triglyceride is re-esterified and stored almost unchanged, so the cost is small.
- 5. Part of the heat is 'facultative' thermogenesis, driven by the sympathetic system, including brown fat (UCP1) in some people.
- 6. SDA does not add usable energy: it is energy lost as heat, so the net energy a food provides is a little lower than its fuel value.
- Also called
- Diet-induced thermogenesis, Thermic effect of food
Clinical notes
- High-protein meals increase satiety and heat production, one reason they are used in weight-loss diets.
- In feeding plans for hospital patients, the thermic effect is part of the usual allowance of about 10 % above resting expenditure.
- When BMR is measured, a recent meal (especially one rich in protein) falsely raises the value.
Pathways
Related conditions
Related
- Energy requirements and basal metabolic rate (BMR)
- Macronutrients and the energy value of food
- Urea cycle
- Protein quality and essential amino acids
- UCP1 (thermogenin)
- Fed, fasting and starvation states
- Leptin, appetite and obesity
Test yourself
Think of the answer, then tap the question to see it.
Which macronutrient has the largest specific dynamic action, and why?
Protein (about 20–30 % of its energy), mainly because deamination, urea synthesis and gluconeogenesis from amino acids cost ATP.
About what fraction of daily energy intake is spent as the thermic effect of food on a mixed diet?
About 10 %.
Why is fat's thermic effect so small?
Dietary triglyceride is stored as triglyceride with little chemical change, so very little ATP is spent processing it.
How does a recent meal affect a measurement of basal metabolic rate?
It raises it falsely, because the specific dynamic action adds heat production; that is why BMR is measured after a 12-hour fast.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Human energy requirements (Food and Agriculture Organization of the United Nations (FAO/WHO/UNU expert consultation), 2004); Metabolism: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).
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Representative model, for educational purposes only.