As you lose weight, your body spends less than the math predicts. The gap runs to 300–500 kcal a day.
Regain is not only about willpower breaking.
Less body weight means less energy spent
A lighter body costs less to move around. That part you can calculate.
The problem is the extra drop beyond the calculation. That is metabolic adaptation.
| 80 kg → 70 kg | Daily expenditure |
|---|---|
| Before the loss | 2,600 kcal |
| Predicted from weight alone | 2,400 kcal |
| Actual | 2,100–2,300 kcal |
The faster you lose, the bigger the drop
Losing a lot quickly takes muscle with it and pulls thyroid hormone and leptin down. Your body shifts into conservation.
Going slower, with protein and resistance training, keeps the drop smaller.
- •Cap weekly loss at 0.5–1% of body weight: 350–700 g a week at 70 kg
- •Protein at 1.6 g per kg of body weight: 112 g at 70 kg
- •Resistance training twice a week: lose muscle and expenditure goes with it
Put maintenance blocks in the calendar
Diet for 8 to 12 weeks, then go back to maintenance calories for 2 to 4 weeks. Hormones and expenditure recover somewhat.
Total loss often ends up larger than pushing the deficit without a break.
Gaining about 1 kg during a maintenance block is mostly glycogen and water. Fat did not come back.
Why keeping it off is harder than losing it
After weight loss, hunger hormones stay elevated for a long time. One study found them still raised a year later.
Spending less and feeling hungrier arrive together. Eat the way you used to and you end up where you used to be.
Watch your waist, not the scale
For a few months after a loss, muscle goes up while fat goes down and the scale sits still.
Still 68 kg with 3 cm off your waist is a plateau that worked.
Sources · research on metabolic adaptation after weight loss (Fothergill et al.) · follow-up studies on appetite hormones after weight loss · International Society of Sports Nutrition protein recommendations