Understanding BMI, Calories and Healthy Weight
BMI, calorie needs and 'ideal weight' are useful starting points for thinking about health — as long as you know what they can and can't tell you.
What BMI is for
Body Mass Index compares your weight to your height. It's a quick population-level screening tool: a BMI between 18.5 and 24.9 is generally considered healthy for adults. But BMI can't tell muscle from fat, so very muscular people may score high despite being lean.
How calorie needs are estimated
Your basal metabolic rate (BMR) is the energy you'd burn at complete rest. The Mifflin–St Jeor equation estimates it from your age, sex, height and weight. Multiplying BMR by an activity factor gives your total daily energy expenditure (TDEE) — roughly the calories needed to maintain your weight.
To lose weight slowly, eat a few hundred calories below your TDEE; to gain, eat above it. These are estimates, so adjust based on what actually happens over a few weeks.
Use the numbers as a guide
Ideal-weight formulas and BMI ranges give a sensible ballpark, not a verdict. Frame size, muscle and overall health all matter. Treat these tools as a conversation starter and consult a professional for anything important.