Average TDEE by Age, Sex, and Activity Level

Estimated calorie needs for moderately active men aged 21-40 are 2,600-2,800 kcal a day, and 2,400 kcal for sedentary men

Estimates for a reference man 5 ft 10 in and 154 lb, from Institute of Medicine energy equations. Adult men overall range from 2,000 to 3,000 kcal a day.

Estimated calorie needs for moderately active women aged 21-40 are 2,000-2,200 kcal a day, and 1,800-2,000 kcal for sedentary women

Estimates for a reference woman 5 ft 4 in and 126 lb. Adult women overall range from 1,600 to 2,400 kcal a day.

Pregnancy adds no calories in the first trimester, about 340 kcal a day in the second and 452 kcal in the third

For women with a healthy pre-pregnancy weight. Breastfeeding adds about 330 kcal a day in the first 6 months and 400 kcal in the next 6.

Energy expenditure adjusted for fat-free mass stays stable from age 20 to 60, even during pregnancy, and declines only in older adults

Doubly labelled water database covering ages 8 days to 95 years. The common idea that metabolism slows sharply at 30 or 40 does not hold once body composition is accounted for.

Fat-free-mass-adjusted energy expenditure peaks at about 50% above adult values around age 1, then declines slowly to adult levels by about 20

The study describes four distinct life stages of energy expenditure.

Free-living daily energy expenditure ranges from about 1.2 × BMR in non-ambulant people to 4.5 × BMR in elite endurance athletes

Analysis of 574 doubly labelled water measurements from affluent societies. Activity multipliers in TDEE calculators sit within this range.

After adjusting for weight, height and age, women expended 11% less energy than men on average

The same gap appeared for total, basal and activity energy expenditure.

Fat-free mass explained 63% of the difference in BMR between people, fat mass 6% and age 2%; 26% remained unexplained

150 white adults in northeast Scotland. Sex had no significant effect once body composition was accounted for; thyroxine explained 25% of the remaining variance in men.

At rest, skeletal muscle uses about 13 kcal per kg a day and fat tissue about 4.5 kcal, while organs and other high-rate tissue use about 54 kcal

Published as 54.4, 18.8 and 225.9 kJ per kg a day, measured in 130 men and 159 women. Swapping 5 kg of fat for 5 kg of muscle adds about 42 kcal a day at rest (our arithmetic).

The Mifflin-St Jeor equation predicted resting metabolic rate within 10% of measured in more people than the Harris-Benedict, Owen or WHO equations

Systematic review in non-obese and obese adults; it also had the narrowest error range. Older adults and US ethnic minorities were underrepresented in the validation studies.

When 16 non-obese adults overate by 1,000 kcal a day for 8 weeks, two-thirds of the rise in their energy expenditure came from non-exercise activity

Changes in fidgeting, posture and daily movement explained the 10-fold differences in fat gained between people (r = 0.77).

Digesting food at energy balance costs 5-15% of daily energy expenditure

The cost is highest for alcohol and protein, then carbohydrate, then fat.

Resistance training is rated at 3.5 METs for multiple exercises of 8-15 reps and 6.0 METs for vigorous lifting, about 245-420 kcal an hour for a 70 kg adult

Codes 02054 and 02050. The kcal range is our arithmetic (1 MET is about 1 kcal per kg an hour) and includes the roughly 70 kcal the person would burn sitting still.

Six years after 'The Biggest Loser', resting metabolic rate was still 704 kcal a day below baseline, and 499 kcal lower than body composition predicted

14 of the 16 original competitors; they had regained 41 of the 58 kg lost. Those who kept more weight off showed more metabolic slowing.

Brown adipose tissue switched on in 23 of 24 young men during mild cold (16°C), but was less active in men with overweight or obesity

No activity was seen at 22°C. Brown fat activity correlated positively with resting metabolic rate; the study did not measure a percentage rise in daily expenditure.