Professional BMR Calculator

The Mifflin-St Jeor equation is generally considered the most accurate formula for calculating BMR in most people. Developed in the 1990s, studies have shown it to be more reliable than the older Harris-Benedict equation, especially for individuals who are overweight or obese. Our calculator provides both for comparison.

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest. TDEE (Total Daily Energy Expenditure) is your BMR plus the calories burned during all other activities, including exercise, digestion, and daily movements. TDEE represents your total daily calorie needs.

Yes. The most effective way to increase your BMR is by building more muscle mass through strength training. Muscle tissue is more metabolically active than fat tissue, so it burns more calories even at rest. Eating enough protein and staying hydrated also support a healthy metabolism.

It is generally not recommended to eat fewer calories than your BMR for a prolonged period. Doing so can slow down your metabolism, lead to muscle loss, and cause nutrient deficiencies as your body enters a 'starvation mode' to conserve energy. Always consult a healthcare professional before starting a very low-calorie diet.

BMR naturally decreases as we age, typically by about 1-2% per decade after age 20. This is primarily due to a gradual loss of muscle mass and changes in hormonal activity. However, maintaining an active lifestyle can help mitigate this decline.

Yes, body temperature has a direct impact on BMR. For every 1°F increase in body temperature (e.g., during a fever), your BMR increases by about 7%. This is because the body's metabolic processes speed up to fight off infection.

Metabolic adaptation, often called 'starvation mode,' is a survival mechanism where the body becomes more efficient at using energy in response to prolonged calorie restriction. Your BMR can drop, making it harder to lose weight. This is why very low-calorie diets are often unsustainable and can backfire.

BMR calculators provide a very good estimate based on population averages. However, they are not 100% precise because they cannot account for individual genetic differences, hormonal health, or specific body composition (muscle vs. fat mass). The most accurate measurement is through indirect calorimetry in a clinical setting, but calculators are an excellent starting point.

Drinking cold water can provide a very minor, temporary boost to your metabolism. Your body must expend energy (calories) to warm the water to body temperature. However, the effect is minimal—drinking a glass of ice-cold water might burn only a few extra calories. Staying hydrated, regardless of water temperature, is more important for overall metabolic health.

Hormones are major regulators of BMR. The thyroid hormones (T3 and T4) are the most significant; an underactive thyroid (hypothyroidism) can lower BMR, while an overactive thyroid (hyperthyroidism) can raise it. Other hormones like cortisol (stress) and adrenaline can also influence metabolic rate.

While cardio burns more calories during the activity itself, strength training is more effective for increasing your long-term BMR. Building and maintaining muscle mass requires more energy than fat, so the more muscle you have, the more calories you burn at rest. A combination of both is ideal for overall health and calorie expenditure.

Lack of quality sleep can negatively impact your BMR. Poor sleep can disrupt the hormones that regulate appetite (ghrelin and leptin) and can increase cortisol levels, which may lead to a slower metabolism and increased fat storage over time. Aiming for 7-9 hours of quality sleep per night supports a healthy metabolic rate.

NEAT stands for Non-Exercise Activity Thermogenesis. It includes all the calories you burn from activities that are not formal exercise, such as walking to your car, fidgeting, typing, or doing household chores. NEAT can have a surprisingly large impact on your TDEE and varies significantly from person to person.

Some foods have a higher Thermic Effect of Food (TEF), meaning your body uses more calories to digest them. Protein has the highest TEF, followed by carbohydrates and fats. Spicy foods containing capsaicin and caffeinated drinks like coffee and green tea can also provide a small, temporary metabolic boost. However, these effects are minor compared to the impact of muscle mass and overall activity.

As you lose weight, your body mass decreases, and your body requires fewer calories to sustain itself. Therefore, your BMR will decrease. It's important to periodically recalculate your BMR and TDEE during a weight loss journey to adjust your calorie targets and avoid hitting a plateau.