How Many Calories Should I Eat? Understanding TDEE

5 min read

Start with your TDEE, the calories you burn in a day: your BMR multiplied by an activity factor from 1.2 for sedentary to 1.9 for very active. Eat about 20 percent below it to lose fat, about 10 percent above to build muscle, then adjust based on your weight after 2 to 3 weeks.

Every calorie target starts with one question: how much do you burn in a day? Once you know that number, fat loss, muscle gain and maintenance are just small adjustments up or down. Here is how to estimate it, set your target and correct it with real results.

BMR vs TDEE

BMR, your basal metabolic rate, is the energy your body uses at complete rest to keep you alive: breathing, circulation, keeping warm. It is the biggest part of your daily burn, but it is not the number to eat.

TDEE, your total daily energy expenditure, adds everything else: walking, working, training and digesting food. It is the number of calories that keeps your weight stable. Eat at your TDEE and you maintain. Eat below it and you lose. Eat above it and you gain.

For most people, BMR makes up the largest share of TDEE, and daily movement outside the gym, such as walking, standing and fidgeting, varies a lot from person to person. That is why two people of the same size can need quite different amounts of food.

How TDEE is estimated

The most widely used method starts with the Mifflin-St Jeor equation for BMR. It uses your weight, height, age and sex: 10 times your weight in kg, plus 6.25 times your height in cm, minus 5 times your age, then plus 5 for men or minus 161 for women.

That BMR is then multiplied by an activity factor. For example, a 30 year old man who weighs 80 kg and is 180 cm tall has a BMR of about 1,780 calories. With moderate activity at 1.55, his TDEE is about 2,760 calories. The result is an estimate. It gets you close, and your scale gets you the rest of the way.

Choosing your activity level

This is where most people go wrong. They count gym sessions and forget they sit at a desk the other 23 hours. Pick honestly; when in doubt, choose the lower level:

▸Sedentary, 1.2: desk job, little or no exercise.
▸Light, 1.375: light exercise 1 to 3 days a week.
▸Moderate, 1.55: moderate exercise 3 to 5 days a week.
▸Active, 1.725: hard exercise 6 to 7 days a week.
▸Very active, 1.9: physical job or training twice a day.

Adjusting for your goal

Once you have your TDEE, set a target based on what you want:

▸Lose fat: eat about 20 percent below TDEE, so multiply by 0.8. For a 2,760 TDEE, that is about 2,200 calories.
▸Build muscle: eat about 10 percent above TDEE, so multiply by 1.1. That gives about 3,040 calories.
▸Maintain or recomposition: eat at your TDEE and focus on training and protein.

Setting your macros

Calories decide whether you gain or lose weight. Macros decide what that weight is made of. Set protein first at around 1.6 to 2.2 g per kg of body weight, which protects muscle when dieting and supports growth when gaining. Set fat at about 25 percent of calories. Fill the rest with carbs, which fuel your training.

For the 80 kg example on a fat loss target of 2,200 calories, that is roughly 145 g protein, 60 g fat and 270 g carbs. You don't need to hit these to the gram. Getting within a small range most days works.

Adjusting after 2 to 3 weeks

Treat your first target as a hypothesis. Weigh yourself first thing in the morning several times a week, after using the bathroom and before eating, and compare weekly averages rather than single days. Water, salt and carbs can swing the scale by a kilo or more overnight.

After 2 to 3 weeks, look at the trend and adjust in small steps:

▸Losing fat: aim for roughly 0.5 to 1 percent of body weight per week. Losing nothing? Drop 150 to 200 calories. Losing much faster? Add 150 to 200.
▸Building muscle: aim for a slow gain of about 0.25 to 0.5 percent per week. Not gaining? Add 150 to 200 calories.
▸Maintaining: if your average drifts up or down, nudge calories by 100 to 150.
▸Recheck every 2 to 3 weeks. Your TDEE falls a little as you lose weight, so targets need updating.

Get your number in a minute

You don't need to do the math by hand. The free TDEE calculator on SSS Workout Assistant uses the same Mifflin-St Jeor method and activity levels described here, then shows your calorie targets for losing fat, maintaining and building muscle, with protein, fat and carbs for each. Start there, track for a few weeks and adjust. If you are pregnant, have a medical condition or a history of disordered eating, work with a doctor or registered dietitian on your targets.

FAQ

Is TDEE accurate?

It is an estimate that is usually close for most people, but it can be off by a few hundred calories either way. That is why the adjustment step after 2 to 3 weeks matters. Your real weight trend is the final answer.

Should I eat back the calories I burn exercising?

No, not if you chose an activity level that includes your training. Your TDEE already accounts for it. Adding exercise calories on top usually double counts them and slows progress.

What is the lowest number of calories I should eat?

Avoid going far below your BMR for any length of time. Very low intakes make it hard to get enough protein and nutrients and to keep training well. A moderate deficit of around 20 percent is sustainable for most people.

Do I need to change calories on rest days?

No. Eating the same amount every day is simpler and works just as well. Your weekly total is what drives results.

Why did my weight jump after starting to lift?

New training causes muscles to hold more water and stored carbs, which can add a kilo or so in the first weeks. It is not fat. Keep going and judge your progress over several weeks.

Put it into practice

SSS Workout Assistant turns these principles into a free weekly routine built around you — then tracks every set and reminds you to train so you actually keep it.

Start training free