BMR vs TDEE: what is the difference?

BMR and TDEE are two different numbers. BMR is the energy your body burns at rest, just to keep you alive. TDEE is BMR plus everything else you do in a day: walking, working, exercising, and digesting food. TDEE equals BMR multiplied by an activity factor, and TDEE is the number you plan your eating around.

What is BMR?

BMR stands for basal metabolic rate. It is the calories your body needs to run its basic systems while you are completely at rest: breathing, keeping your heart beating, maintaining body temperature, and repairing cells. It does not include walking to the kitchen, working at a desk, or going to the gym.

The most widely used way to estimate BMR is the Mifflin-St Jeor equation. For men it is 10 times weight in kilograms, plus 6.25 times height in centimetres, minus 5 times age in years, plus 5. For women the same formula ends with minus 161 instead of plus 5. The result is an estimate. Two people with the same age, height, and weight can still have different BMRs, because muscle burns more energy at rest than fat does.

What is TDEE?

TDEE stands for total daily energy expenditure. It is BMR plus the energy of everything you do: moving around, exercising, digesting food, and even fidgeting. If BMR is what you burn lying still, TDEE is what you burn living a normal day.

You get TDEE by multiplying BMR by an activity factor. The standard factors are 1.2 for sedentary, 1.375 for lightly active, 1.55 for moderately active, 1.725 for very active, and 1.9 for extra active. Pick the factor that matches your real week. A desk job with a gym session three times a week counts as moderately active. Picking a higher factor is the most common reason a TDEE estimate feels too high.

How BMR and TDEE relate

TDEE always sits above BMR, because it starts with BMR and adds activity on top. The gap between the two numbers is the energy of your day. A sedentary person has a small gap. A very active person has a large one. The formula is one line: TDEE equals BMR multiplied by your activity factor.

Why BMR alone is not a calorie target

Eating at your BMR means eating less than you burn in a day. Your body still has to move, digest food, and keep you warm. If you eat at BMR for long, the gap becomes a deficit, and the deficit becomes weight loss. That can suit a short, planned cut, but it is a poor daily target, because the target should reflect the life you live.

A worked example

Here is the same example the calculator uses. A 30-year-old man, 80 kilograms, 180 centimetres, moderately active. His BMR is 10 times 80, plus 6.25 times 180, minus 5 times 30, plus 5, which comes to 1,780 calories a day. Multiply that by 1.55 and his TDEE is 2,759 calories a day. For weight loss, 500 less gives a cut target of 2,259. For weight gain, 500 more gives a bulk target of 3,259. Those targets are starting points. What matters is what happens over the next few weeks.

Common mistakes

The first mistake is eating at BMR and calling it a plan. BMR is what you burn lying still, so eating at BMR is undereating. The second is picking an activity factor for the person you want to be instead of the person you are. The third is treating the number as exact. The formula comes from population averages, so it is less accurate for very muscular people, very small people, and older adults. Track what happens and adjust.

Frequently asked questions

Should I eat at my BMR to lose weight?

No. Eating at BMR leaves you below what you burn in a day, because BMR does not include any activity. Weight loss comes from eating below TDEE. A common starting point is 500 calories below TDEE.

Can my TDEE be lower than my BMR?

No. TDEE is BMR plus activity, so it is always at least as high as BMR. The lowest activity factor is 1.2. If a calculator shows TDEE below BMR, the numbers were entered wrong.

How often should I recalculate my TDEE?

Recalculate when something changes: your weight, your age, or how active you are. Weight matters most, because a smaller body burns less. Check your numbers every month or two.

Estimates only, not medical advice. These numbers come from a formula, not from measuring your body. If you have a medical condition, talk to a doctor or registered dietitian first.

Try it yourself in the TDEE calculator, then read what TDEE is and how it is calculated.