What is the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest just to keep you alive -- breathing, circulating blood, and maintaining organ function. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor, representing the total calories you actually burn in a day including movement and exercise.

How many calories should I eat to lose weight?

To lose weight at a sustainable rate of about 1 pound per week, eat roughly 500 calories below your TDEE each day. This creates a weekly deficit of 3,500 calories, which corresponds to approximately one pound of fat. Avoid cutting more than 750-1,000 calories below TDEE, as extreme deficits can cause muscle loss and metabolic slowdown.

Does my calorie need change as I age?

Yes. BMR decreases by roughly 1-2% per decade after age 20, primarily due to loss of lean muscle mass. A 40-year-old typically needs about 100-200 fewer calories per day than they did at 25, all else being equal. Maintaining muscle through strength training can help offset this decline.

How Many Calories Should I Eat? A Practical Guide to TDEE and BMR

By Nicholas Vogler -- March 13, 2026 -- 5 min read

The number of calories you should eat depends on your body size, age, sex, and how active you are. There is no single number that works for everyone. But there is a reliable method to estimate your personal calorie needs, and it starts with two concepts: BMR and TDEE.

What Is BMR?

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest -- the energy required to keep your heart beating, lungs breathing, and organs functioning. If you stayed in bed all day and did absolutely nothing, your BMR is roughly what you would burn.

The most widely used formula for estimating BMR is the Mifflin-St Jeor equation:

Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5

Women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161

For example, a 30-year-old man who is 5'10" (178 cm) and weighs 180 lbs (82 kg) would have a BMR of approximately 1,782 calories per day.

What Is TDEE?

Your Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor. This gives a more realistic estimate of how many calories you actually burn each day, including walking, working, exercising, and even fidgeting.

Activity Level	Description	Multiplier
Sedentary	Desk job, little or no exercise	1.2
Lightly Active	Light exercise 1-3 days/week	1.375
Moderately Active	Moderate exercise 3-5 days/week	1.55
Very Active	Hard exercise 6-7 days/week	1.725
Extremely Active	Athlete or very physical job + training	1.9

Using our example (BMR of 1,782), if this person exercises moderately 3-5 days per week, his TDEE would be 1,782 × 1.55 = approximately 2,762 calories per day. That is his maintenance level -- eating this amount should keep his weight stable.

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Calculate Your TDEE

Calories for Weight Loss

To lose weight, you need to eat fewer calories than your TDEE. A deficit of about 500 calories per day results in roughly 1 pound of fat loss per week (since one pound of fat contains approximately 3,500 calories).

Using our example person with a TDEE of 2,762:

Moderate deficit (1 lb/week): 2,762 - 500 = 2,262 calories/day
Aggressive deficit (1.5 lb/week): 2,762 - 750 = 2,012 calories/day

Avoid going below your BMR for extended periods. Eating less than about 1,500 calories (for men) or 1,200 calories (for women) can cause muscle loss, nutrient deficiencies, and metabolic adaptation that makes future weight loss harder.

Calories for Muscle Gain

Building muscle requires a caloric surplus -- eating more than your TDEE -- combined with resistance training. Most people do well with a surplus of 250-500 calories per day, which supports muscle growth while minimizing excess fat gain.

For our example person: 2,762 + 300 = approximately 3,062 calories/day for a lean bulk.

Protein intake matters as much as total calories when building muscle. A common recommendation is 0.7-1.0 grams of protein per pound of body weight. For a 180 lb person, that is 126-180 grams of protein daily.

Why Calorie Calculators Are Estimates

All calorie formulas are approximations. Your actual needs can vary based on:

Genetics -- some people have naturally higher or lower metabolic rates
Body composition -- muscle burns more calories at rest than fat
Hormones -- thyroid function, testosterone, and other hormones affect metabolism
Non-exercise activity thermogenesis (NEAT) -- some people fidget, stand, and move more throughout the day
Thermic effect of food -- protein requires more energy to digest than carbs or fat

The best approach is to use a calculator as a starting point, then adjust based on real-world results. If you are losing weight too fast (more than 1-1.5 lbs per week), eat a bit more. If your weight is not moving after 2-3 weeks, reduce by 100-200 calories.

BMI: A Quick Health Check

While calories control your weight, Body Mass Index (BMI) gives a rough snapshot of whether your weight falls in a healthy range for your height. BMI is not perfect -- it does not distinguish between muscle and fat -- but it is a useful screening tool.

You can check your BMI with our free BMI calculator to see where you fall on the scale and what the ranges mean for health risk.

Practical Tips for Hitting Your Calorie Target

Track for 2 weeks to build awareness. You do not need to track forever, but most people underestimate how much they eat by 20-40%. Two weeks of honest tracking recalibrates your sense of portion sizes.
Prioritize protein and fiber. Both keep you feeling full longer, making it easier to stick to a deficit.
Do not drink your calories. Sodas, juices, and specialty coffee drinks can add 300-800 calories per day without making you feel full.
Eat enough to support your training. If you exercise regularly, undereating will hurt your performance, recovery, and long-term results.

The Bottom Line

Start by calculating your TDEE using our TDEE calculator. That gives you a maintenance number. Then adjust based on your goal: subtract 500 for weight loss, add 250-500 for muscle gain, or eat at maintenance. Track your weight over a few weeks and adjust if needed. The formula gets you in the ballpark -- consistency and patience do the rest.