How we calculate your target

Resting energy is the energy your body uses at rest. We estimate it from your age, sex, height and weight using published equations (Mifflin–St Jeor, Roza–Shizgal and Henry) and compare them. When they agree closely we say so; when they spread apart we tell you the estimate is less certain rather than hiding it.

If you give a body-fat percentage from a method we trust, a fat-free-mass equation (Cunningham) can also be shown. Less reliable methods, such as smart scales or visual estimates, are treated more cautiously.

Activity is judged from three things together — your daily steps, the kind of work you do, and your strength, cardio and sport training — rather than one broad “activity level” picker. That gives an activity category, which is used with the National Academies (NASEM) total-energy-expenditure equations to estimate the calories that would keep your weight steady.

We cross-check this against a second method. If the two differ noticeably, your result carries a lower-confidence note.

A fat-loss or muscle-gain target is your maintenance estimate moved by a chosen rate of change, expressed as a percentage of bodyweight per week, rather than a flat calorie number. A smaller rate is gentler and easier to sustain; a larger one changes the calories more.

Some rates are not appropriate for some people (for example very large deficits, a very low calorie level, or a projected body-mass index that would be too low). When a choice is not advised we say so and offer a safer alternative, or decline to give a target, rather than presenting it as normal.

Protein is set first, scaled to your body and your goal — higher when you are dieting and lifting, because research supports protecting muscle. A minimum amount of fat is protected for general health, and carbohydrate takes up the remaining calories to fuel training and daily life. If training demands more carbohydrate than the plan can supply, we flag that instead of quietly cutting it.

Every equation is an average across many people. Individual metabolism, real-world activity and how accurately food is tracked can each move your true needs meaningfully in either direction. Your Working Calorie Target is therefore a planning figure — a starting point to test — and not a measurement of your metabolism or your exact total daily energy expenditure (TDEE).

The 14-day check-ins compare what actually happened (your weight trend, reported intake and how you felt) with what the estimate predicted. Over several comparable periods we can see how far your real response sits from the formula and adjust your target from your own evidence rather than an average.

Periods that cannot fairly be judged — too few weigh-ins, intake far from target, an unusual fortnight, or a change in your routine — are held back from calibration instead of being over-interpreted.

Early weight change includes shifts in water and stored carbohydrate that say little about fat change, so the first check-in is treated as a settling-in period rather than evidence about your metabolism. It is not used as calibration evidence, and any change it prompts is kept modest.

We keep these two things separate on purpose.

From published research

• The resting-energy equations and the NASEM energy-expenditure equations.
• Evidence on energy balance and body-weight change, rate of loss and lean-mass retention, and protein intake for people who train.

Calorie Target Lab operating rules (our own choices)

• Adjusting targets in small steps (about 2.5% or 5% at a time) and never by large jumps automatically.
• Reading the first check-in conservatively and treating some periods as “held” rather than evidence.
• How many comparable periods are needed before a target counts as validated, and how much of your calibration carries into a new goal.
• The default and conservative rates offered, the weigh-in and tracking thresholds, and our safety limits.

These rules are practical judgements informed by the research, not published findings, and we may refine them as we learn.

Calorie and macro calculations are estimates, not measurements, and are not a substitute for advice from a suitably qualified professional — especially if you have a medical condition, a history of disordered eating, or are pregnant or breastfeeding (which this version does not support). See the Terms and health disclaimer.

• Resting energy — Mifflin–St Jeor. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241–247.
• Resting energy — Roza–Shizgal. Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr. 1984;40(1):168–182.
• Resting energy — Henry (Oxford). Henry CJK. Basal metabolic rate studies in humans: measurement and development of new equations. Public Health Nutr. 2005;8(7A):1133–1152.
• Resting energy from fat-free mass — Cunningham. Cunningham JJ. Body composition as a determinant of energy expenditure: a synthetic review and a proposed general prediction equation. Am J Clin Nutr. 1991;54(6):963–969. doi:10.1093/ajcn/54.6.963
• Total energy expenditure — NASEM. National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Energy. Washington, DC: The National Academies Press; 2023.
• Weight change and energy balance. Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826–837.
• Rate of weight loss and lean mass. Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab. 2011;21(2):97–104.
• Protein and resistance training. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376–384.
• Protein while dieting. Helms ER, Zinn C, Rowlands DS, Brown SR. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. Int J Sport Nutr Exerc Metab. 2014;24(2):127–138.