Common questions about calories, BMR and weight loss
TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns in a day, including your basal metabolic rate (BMR) plus calories burned through activity and digestion. It is your maintenance level: eat at it and your weight is broadly stable.
It uses the Mifflin-St Jeor equation, which is generally considered the most accurate of the widely used BMR formulas. Individual results still vary by roughly 5–10% because of genetics, body composition and metabolic differences, and the gap is wider for very muscular people, whose needs tend to be underestimated. Use the number as a starting hypothesis and adjust from what your weight actually does over two to three weeks.
To lose about 1 pound per week, subtract 500 calories from your TDEE. For about 2 pounds per week, subtract 1,000. Do not go below roughly 1,200 calories a day for women or 1,500 for men without medical supervision — below that it becomes difficult to meet basic nutrient needs, and muscle loss accelerates.
Post-surgery needs vary by phase. Recent patients (0–6 months) typically need 800–1,000 calories with 60–80 g protein. The recovery phase (6–12 months) is usually 1,000–1,200 calories. Long-term maintenance commonly settles at 1,200–1,500. Always follow your surgeon's specific guidance and prioritise protein at every meal — our bariatric nutrition guide compares the ASMBS and Academy of Nutrition and Dietetics targets phase by phase.
Almost always because your maintenance level moved. A lighter body burns fewer calories, so the intake that created a 500-calorie deficit at the start eventually matches your new TDEE. Recalculate at your current weight rather than cutting harder. Water retention, an unusually salty few days, and inconsistent weigh-in timing also mask real fat loss for a week or two at a time.
Both work identically — the calculator converts internally and produces the same answer either way. Use whichever you can estimate in without converting in your head, since a confident guess in familiar units beats a shaky conversion.
Because the formula genuinely uses them. Mifflin-St Jeor is (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5 or − 161, so height and age each move the result substantially. A calculator that asks only for weight has to assume the rest, and that assumption is wrong for most people. Our how it works page shows the full equation.
No. BMR is what your body burns at complete rest — it is a reference point, not a target. Eating at BMR while also being awake and moving creates a very large deficit. Your target should be based on TDEE, adjusted for your goal.
Most people should choose one level lower than they first think. A desk job with three gym sessions a week is "light" to "moderate," not "active." Overstating activity is the most common reason a calculated target fails to produce results, and it is worth revisiting before you conclude the formula is wrong.
No. It runs entirely in your browser — your height, weight, age and activity level are used to do the arithmetic on your own device and are never transmitted to us or stored. Closing the page discards them. See our privacy policy.