Recalculate maintenance calories at a new weight.
Maintenance calories fall as you get lighter, which is why a diet that worked for two months stops working in the third. The Mifflin-St Jeor equation makes the mechanism explicit: resting metabolic rate includes a term of ten calories per kilogram, so losing ten kilograms removes about a hundred calories from resting expenditure alone, and the activity multiplier scales that loss up to roughly 150-190 calories of total maintenance. On top of the arithmetic there is adaptive thermogenesis — a genuine additional downshift of perhaps five to ten percent after sustained restriction, driven by reduced spontaneous movement and hormonal changes. Rechecking every four or five kilograms, and comparing the new figure with the old, is what keeps a deficit real rather than notional.
Mifflin-St Jeor maintenance at a new weight
RMR = 10 x weight in kg + 6.25 x height in cm - 5 x age + 5 for men or -161 for women; maintenance = RMR x activity multiplier (1.2 sedentary to 1.9 athlete)
Predictive equations carry an individual error of roughly plus or minus ten percent and are not medical advice. Metabolic rate is affected by thyroid function, medication, pregnancy and body composition. Consult a doctor or registered dietitian before acting on a calorie target.
Every four to five kilograms of change, or whenever progress stalls for three consecutive weeks with adherence unchanged. Below that the shift is smaller than day-to-day measurement noise.
Adaptive thermogenesis. After sustained restriction, spontaneous movement falls and hormonal changes reduce expenditure by roughly five to ten percent beyond what body mass predicts. If measured intake disagrees with the equation, trust the measurement.
Most people overestimate. Unless your job is physical, a desk-based life with three or four gym sessions is 'moderate' at most, and picking the level above yours is the single most common reason a calculated deficit does not produce loss.