How to Calculate Your Total Daily Energy Expenditure the Right Way

First you estimate your resting metabolic rate, the energy your body uses at rest. Of the common formulas, the Mifflin-St Jeor equation is the one to use. A systematic review comparing predictive equations found it was the most reliable for healthy adults, predicting resting rate within 10 percent of measured values more often than the alternatives. Here it is, using kilograms, centimetres, and years.

Work through a quick example. A 35-year-old woman who is 168 cm and 70 kg gets: 700, plus 1,050, minus 175, minus 161, which comes to about 1,414 calories a day at rest. That is her resting burn, the foundation of everything else, but not yet her full daily expenditure.

Your resting rate is what you would burn lying in bed all day. To estimate your real total, multiply it by an activity factor that reflects how much you move. This is the least precise step, so be honest and, if in doubt, pick the lower option.

Take the same woman with a resting rate of 1,414. If she trains three or four times a week and is otherwise moderately active, a multiplier of 1.55 gives an estimated TDEE of about 2,190 calories a day. That is her starting number. Notice how much rides on the multiplier: shifting from 1.375 to 1.55 changes her estimate by roughly 250 calories, which is why the correction step below matters so much.

This is the step that separates a useful number from a guess, and the one most people skip. Your calculated TDEE is a hypothesis. To test it, eat at that number as consistently as you can, weigh yourself several times a week, and take the weekly average to smooth out daily noise from water and food. After two to three weeks, the trend tells you the truth.

1. Eat at your estimated TDEE. Track your intake honestly for two to three weeks, aiming to hit your calculated number most days.
2. Weigh in regularly. Take several weigh-ins a week and use the weekly average, not any single morning, because daily weight swings a lot with water and food.
3. Read the trend. If your average weight held steady, your estimate was close. If it rose, your true TDEE is lower. If it fell, it is higher.
4. Adjust and repeat. Nudge your number by about 100 to 200 calories in the right direction, then confirm over another couple of weeks.

A useful reality check on why the trend, not the day, is what counts: mathematical modelling of body weight shows that your weight responds slowly to a change in intake, with much of the effect playing out over many months rather than days. So do not panic-adjust after a single bad weigh-in. Give the trend two to three weeks to reveal itself before you change anything.

Your TDEE is not fixed, so a number you nailed three months ago may be wrong today. As you lose weight, a lighter body burns less, so your TDEE falls and a fat-loss target that once worked will eventually stall. As you gain muscle or move more, it rises. Plan to recheck your estimate whenever your weight changes by a few kilograms or your activity shifts noticeably.

The whole method comes down to a simple loop: estimate with a good equation, eat at that number, watch the weekly trend, and correct. Trust the data your own body gives you over any calculator's confident output. A calculator cannot see how much you fidget, how hard you actually train, or how your metabolism has adapted, but your weight trend quietly accounts for all of it.