A worked example
A 35-year-old woman, 168 cm and 78 kg, aiming for 70 kg, burns about 2,050 kcal a day with a desk job and a little training. At the standard pace she eats about 1,550 kcal, a deficit of 500 kcal, and gets to her goal in around 18 weeks.
How the target is worked out
First comes your daily burn, the same estimate as the TDEE calculator: Mifflin-St Jeor for the resting part, and your two answers for activity. The pace then takes 250, 500 or 750 kcal a day off it, the presets the Ampsu app offers. A kilogram of body fat holds about 7700 kcal, so 500 a day comes to roughly 0.45 kg a week.
| Pace | kcal a day under your burn | Loss a week | Weeks to lose 5 kg |
|---|---|---|---|
| Lose slowly | 250 | 0.23 kg | 22 |
| Lose weight | 500 | 0.45 kg | 11 |
| Lose faster | 750 | 0.68 kg | 7 |
How big a deficit is sensible?
About 500 kcal a day is where most people start: around half a kilo a week, slow enough to live with. Faster is possible, but hunger, training and sleep tend to suffer, and a pace you drop after three weeks loses less than a slower one you keep. Targets never go below 1200 kcal a day here, the same floor the app uses.
Why the weeks are only a rough guide
Loss slows as you go, because a lighter body burns less, which is the main finding of Hall and colleagues’ model of weight change. The scale also bounces with water from day to day. The weeks here assume the deficit stays the same, so read them as the right order of magnitude, and recalculate every few kilos.
Questions people ask
Should I eat less on rest days?
You don’t need to. The activity answers already average your week, so one target for every day works. Shifting a little from rest days to training days is fine, as long as the week adds up.
Do I eat back the calories from exercise?
Not the training you counted in the first question, or it’s counted twice. A long hike or an unplanned match on top of your usual week is fair to eat partly back.
What if I stop losing?
A few flat weeks are common, often water hiding fat loss. If the trend stays flat for three or four weeks, the burn estimate was probably too high. The adaptive TDEE calculator works out your real burn from a few weeks of eating and weighing.