Your calorie goal, calculated step by step

The principle

To lose, keep or gain weight, everything starts from an estimate: how much energy your body spends in a day. Azetta calculates it in three pieces that it adds together — what your body burns at rest, what your everyday life adds, and what your training costs — then applies the pace you chose (maintain, gentle loss, loss or muscle gain).

Each piece is shown on the "Calorie goal" screen: you see where the final number comes from, line by line.

The Azetta method

1. Basal metabolic rate

This is the energy spent at complete rest. Azetta uses the Mifflin-St Jeor equation, with your weight, height and age:

If you have not specified your sex, the app uses −78, exactly halfway between the two constants.

2. Everyday life

The basal metabolic rate is multiplied by a fixed factor of 1.35. It covers your commuting, your work, the stairs — everything except training. This factor lies between "sedentary" (1.2) and "lightly active" (1.375): the app doesn't know your job, so it takes a cautious value that is the same for everyone.

3. Training, counted only once

The calories from your sessions are added separately, in kilocalories, not hidden in an activity multiplier. That way, a rest day is not inflated by the other days' sessions, and a busy day gets what it really costs. How these calories are calculated is detailed in the article on calories burned.

On the day itself, a planned session counts as long as the day isn't over; once it is logged, the actual session replaces it. A sport session without an answer is never assumed to have been done.

4. The pace

To maintenance, Azetta adds a fixed daily difference depending on the chosen pace:

By default, the pace follows your goal: weight loss → loss (−500), body sculpting → gentle loss (−300), muscle gain → muscle gain (+300), other goals → maintain. If your main goal is maintenance but you have added weight loss as a secondary goal, the pace becomes gentle loss.

5. The floor

The goal never goes below your basal metabolic rate. It is then rounded to the nearest ten kilocalories.

Why this choice

• Mifflin-St Jeor is the equation that, in published comparisons, best predicts resting metabolic rate in healthy adults, whether lean or overweight. It only needs data you know.
• A modest factor plus actual training avoids counting exercise twice: the classic multipliers (1.55 or 1.725) already include sessions, and adding training calories on top inflates the expenditure.
• Fixed differences in kilocalories are simple to understand and adjust. A difference of 500 kcal per day matches the order of magnitude usually recommended for gradual weight loss.
• The floor at basal metabolic rate stops the app from suggesting a diet that is too low, even with a small frame and a loss pace.

Limits

• Any equation gives an average: your actual metabolism may differ from it by several hundred kilocalories.
• The 1.35 factor knows neither your job nor your steps: a delivery driver or a waiter who walks all day spends more, a remote worker less. Steps recorded in the app are not added to the expenditure.
• Body fat is not used: two people with the same weight but different body composition get the same estimate.
• The goal does not recalibrate automatically based on how your weight changes: it is up to you to change the pace if the trend doesn't follow.
• The weight used is the one in your profile, not your latest weigh-in: update it when it changes.

References

1. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990;51(2):241-247.
2. Frankenfield D, Roth-Yousey L, Compher C. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. Journal of the American Dietetic Association, 2005;105(5):775-789.