Energy in, energy out
Your body burns energy all day: to keep you alive at rest, to digest food, and to move. When you take in less than that total for a sustained period, the difference comes from stored energy, mostly fat when protein and training are in place.
Calorie maths is not precise, and bodies adapt a little. It is still the most reliable lever there is, and it works best as a gentle, steady deficit rather than a crash.
What the scale will do
Weight swings up and down by a kilogram or more from day to day with water, salt, carbohydrate and digestion. Trends matter, single weigh-ins do not.
Expect a faster drop in the first week or two (mostly water and gut content), then a steadier line. Plateaus of a week or two are normal and often break on their own.
Do
- Weigh at the same time, most mornings
- Compare weekly averages, not single days
- Keep protein high and keep lifting
- Walk more: steps add up without tiring you
Avoid
- Cutting calories so hard that training falls apart
- Judging progress after three days
- Dropping protein to "save" calories
- Trying to burn fat from one area with crunches
Common myths
A simple plan
- Find maintenanceUse the calculator above, then watch your weight for two weeks to calibrate.
- Set a modest deficitStart around 15–20% below maintenance.
- Anchor protein and trainingKeep protein high and keep lifting to protect muscle.
- Review every two weeksIf the weekly average has not moved in three weeks, trim about 100–150 kcal or add steps.
- A steady 0.5–1% of body weight a week is a good pace
- Water hides fat loss day to day: watch the weekly trend
- Protein and strength training protect your muscle
General information, not medical advice. If you have a health condition, are pregnant, or take medication, check with a professional first. See the medical disclaimer.
- Mifflin MD, St Jeor ST et al. A new predictive equation for resting energy expenditure. Am J Clin Nutr, 1990.
- Hall KD et al. Quantification of the effect of energy imbalance on bodyweight. Lancet, 2011.
- Helms ER et al. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition. JISSN, 2014.
- Vispute SS et al. The effect of abdominal exercise on abdominal fat. J Strength Cond Res, 2011.