Glossary

Terms used across the reference. Anything that rests on research carries a link to a publication, so a definition can be checked rather than taken on trust.

Supplement reference Methodology and levels

Energy and nutrition

Basal metabolic rate (BMR)

How many calories the body spends at complete rest: breathing, heartbeat, maintaining temperature. Estimated with the Mifflin–St Jeor or Katch–McArdle formulas, which are off by 10–15 % for an individual.

A new predictive equation for resting energy expenditure in healthy individuals · Mifflin MD, St Jeor ST, Hill LA · The American journal of clinical nutrition, 1990 · PMID 2305711
Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review · Frankenfield D, Roth-Yousey L, Compher C · Journal of the American Dietetic Association, 2005 · PMID 15883556

Total daily energy expenditure (TDEE)

Basal rate plus daily activity, training and digestion. The deficit or surplus is calculated from this number — it is what the calculator shows.

Calorie deficit

Spending more than you take in. The main mechanism of weight loss; the rate is capped so that you do not lose muscle or burn out.

Energy availability

How much energy remains after training expenditure. Chronically low availability harms hormonal function, bones and recovery.

Metabolic adaptation to weight loss: implications for the athlete · Trexler ET, Smith-Ryan AE, Norton LE · Journal of the International Society of Sports Nutrition, 2014 · PMID 24571926

Protein intake

How much protein per day is needed for muscle to grow and be retained. The figure depends on the goal and training experience rather than being the same for everyone.

Training

Hypertrophy

Growth of muscle size. The controllable factors are training volume, proximity to failure and load progression; nutrition and sleep create the conditions.

Volume (sets per week)

How many working sets a muscle group gets per week. The link to growth is dose-dependent, but past a certain threshold fatigue grows rather than results.

Frequency per muscle group

How many times a week a muscle group is trained. At equal weekly volume, two sessions usually work no worse than one and often better.

Effects of Resistance Training Frequency on Measures of Muscle Hypertrophy: A Systematic Review and Meta-Analysis · Schoenfeld BJ, Ogborn D, Krieger JW · Sports medicine (Auckland, N.Z.), 2016 · PMID 27102172

RIR — reps in reserve

Reps in reserve: how many reps remained before failure. RIR 2 means you could have done two more. It helps keep the intended proximity to failure without going to the limit.

Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy: A Systematic Review with Meta-analysis · Refalo MC, Helms ER, Trexler ET · Sports medicine (Auckland, N.Z.), 2023 · PMID 36334240

Progressive overload

A gradual increase in the load: sets, weight or reps. Without it adaptation stops, however much you train.

Low and high load

At comparable effort, a low load with many reps produces similar hypertrophy; for maximal strength heavier weights have the advantage.

Strength and Hypertrophy Adaptations Between Low- vs. High-Load Resistance Training: A Systematic Review and Meta-analysis · Schoenfeld BJ, Grgic J, Ogborn D · Journal of strength and conditioning research, 2017 · PMID 28834797

Concurrent training

Combining strength and aerobic work in one cycle. Interference is possible, but its size depends on volume, frequency and recovery rather than the combination itself.