What do the results mean?
Your basal metabolic rate (BMR) is the energy your body burns at complete rest to keep you breathing, circulate blood and repair cells. Your total daily energy expenditure (TDEE) is BMR multiplied by an activity factor, and it is roughly how much you need to eat to keep your weight stable.
The goals in the table are calculated from that maintenance number. A deficit of about 500 kcal a day corresponds to roughly 0.45 kg (1 lb) of loss per week, while a 250-500 kcal surplus supports controlled weight gain. The math assumes that about 7,700 kcal equals 1 kg of body weight.
Which formula is used?
The calculator uses the Mifflin-St Jeor equation, which studies have shown to be the most accurate predictive equation for modern adults:
Men: BMR = 10 x weight (kg) + 6.25 x height (cm) - 5 x age + 5 Women: BMR = 10 x weight (kg) + 6.25 x height (cm) - 5 x age - 161
BMR is then multiplied by an activity factor: sedentary 1.2, lightly active 1.375, moderately active 1.55, very active 1.725, extra active 1.9. If you enter pounds and feet, the values are converted to metric before calculating. The body analysis in the Kilotaki app uses the same formula, so your numbers stay consistent.
Which target should I pick?
For most people a sustainable pace is about 0.5-1% of body weight per week. A 500 kcal deficit is a good starting point; a 1,000 kcal deficit should only be considered by people with significant excess weight, and only for a limited time. If you want to build muscle, starting with a 250 kcal surplus keeps fat gain in check.
Treat the result as a starting estimate, not a rule. Track your weight and food for two to three weeks; if your weight is not moving at the pace you expect, adjust your target by 100-200 kcal. That feedback loop beats any formula.
Limitations
Mifflin-St Jeor was developed for adults with average body composition. It can underestimate needs in very muscular athletes and slightly overestimate them in people with obesity. It lands within 10% of measured values for most people; for the rest the error is larger.
Activity level is the biggest source of error: most people overestimate how active they are. If you are unsure, pick one level lower. Lower targets in the table are never set below the commonly recommended minimum without medical supervision (1,200 kcal for women, 1,500 kcal for men); rows that hit that floor are marked with an asterisk.
When to see a doctor
If you are pregnant or breastfeeding, under 18, have diabetes, thyroid, kidney or heart disease, or take medication regularly, set your calorie target with a doctor or registered dietitian. Unexplained rapid weight loss or gain, constant fatigue, dizziness or a history of disordered eating are also reasons to get professional support.