How to use bmr for weight loss?

Your BMR is calculated based on several different factors that focus on your age, gender, current weight and activity level. Although BMR is not intended for  weight loss , the tool can show you information that can help you set a realistic caloric intake for yourself--whatever your goal may be.

Keep reading to learn more about BMR, how to calculate it and how it can be a guide for your nutrition and exercise goals.

Many people use BMR as a starting point to calculate their daily calorie needs and how to best adjust them to reach their goals. In fact, many macro calculators, like the popular IIFYM, incorporate BMR into their calculations for telling you about your calorie intake and macro needs based on your goals.

One common misconception about BMR is that it is the amount of calories your body burns at rest, but that is a different metric -- resting metabolic rate, or RMR. Your BMR is what energy your body needs to perform basic functions, while RMR is the amount of calories that your body burns while at rest. Some people use the measurements interchangeably, but they aren't necessarily the same thing.

There are many different calculators available online that can calculate your estimated BMR. Note that some of them will ask you to enter your body fat percentage, which many people do not know. If you don't, you can make an estimate or use the images provided (like IIFYM does) to guess.

Some of the best BMR calculators:

Once you start learning about your BMR, you will likely also find information on total daily energy expenditure, or TDEE, since BMR is often calculated first to find TDEE.

Your BMR tells you your calorie needs, when you take that number plus how much you burn every day during normal activity and exercise, you get your TDEE. So really, TDEE is the number that you work off of for figuring out how to adjust macros or calories for body composition goals, according to IIFYM.

Weight loss is tricky, but using calculators that factor in your BMR are helpful for taking a more customized approach for your calories and macronutrient needs. The way that most macros and BMR-based calculators work is by factoring in your TDEE with your goals.

If you want to lose weight, you have to be in a calorie deficit, meaning the calculator will set your daily food intake to equal less calories than what you burn. Sometimes when you take an online quiz to find this number, you will be asked how fast you'd like to lose weight. Then the calorie deficit will be adjusted accordingly. The faster you want results, the more extreme you will have to be with cutting calories. But many experts say that slow and steady is optimal compared to trying to lose a lot of weight quickly.

Your Basal Metabolic Rate (BMR) is the number of calories you burn at rest. The safest way to handle a caloric reduction for fat loss is to reduce your intake by something marginal and being consistent. To optimize your BMR for lean body mass gain, you need to exceed the number of calories you require each day.

That's why men naturally enjoy a higher BMR than women, as they tend to have more overall body size and lean mass levels, explains Sari Greaves, RDN, a registered dietitian-nutritionist at LBS Nutrition in East Brunswick, New Jersey, and author of Cooking Well.

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BMR is often used interchangeably with resting metabolic rate, or RMR, but they are slightly different.

“BMR is the absolute minimum metabolic rate,” Church says. It is typically determined only in laboratory settings, with people undergoing measurements in a darkened, temperature-controlled room immediately after 8 hours of sleep and 12 hours of fasting and reclining, according to the American Council on Exercise.

Meanwhile, “RMR is metabolic rate when at rest, awake, and sitting still.” RMR testing does not require a fast and may be performed later in the day. RMR is typically 10 to 20 percent higher than BMR, according to the National Strength and Conditioning Association.

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Knowing your BMR or RMR can help you better determine your total daily energy expenditure in order to create a caloric deficit, defined as consuming fewer calories each day than you burn for energy. A caloric deficit is required to lose weight.

But because most people do not have access to state-of-the-art labs that are required to determine BMR, equations are often used to make approximations. The easiest way to measure your metabolic rate is to use an online calculator. You can find many calculators online, and all use varying equations.

The commonly used metabolic equation, called the Harris and Benedict equation, was first designed in 1918 (and updated in 1984). While it was intended to estimate BMR, it actually estimates RMR, according to the National Academy of Sports Medicine. It uses height, weight, biological sex, and age to determine RMR and is based on average lean mass levels. The Mifflin-St Jeor equation is another equation that uses the same variables but may be more accurate, Church says.

Other metabolic equations, such the Cunningham equation, use your total levels of lean body mass, which is a primary determiner of BMR and therefore RMR. Yet using such a calculator requires you to be able to measure your body’s levels of fat versus free-fat mass, Church says. Calipers and smart scales are two popular at-home options, while the most accurate measures are performed in professional and laboratory settings.

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Below, you can see how estimated RMR varies based on the equation used.

Men: (88.40 + 13.40 x weight in kg) + (4.80 x height in cm) – (5.68 x age in years)

For example, if a man is 180 pounds, 5'11", and 43, his RMR is 1,804 calories.

Women: (447.60 + 9.25 x weight in kg) + (3.10 x height in cm) – (4.33 x age)

For example, if a female is 130 pounds, 5'3", and 36, her RMR is 1,333 calories.

Men: (9.99 x weight in kg) + (6.25 x height in cm) – (4.92 x age in years) + 5

For example, if a male is 180 pounds, 5'11", and 43, his RMR is 1,734 calories.

Women: (9.99 x weight in kg) + (6.25 x height in cm) – (4.92 x age in years) – 161

For example, if a female is 130 pounds, 5'3", and 36, her RMR is 1,249 calories.

Men and women: 500 + (22 x lean body mass in kg)

For example, if a man is 170 pounds, 5'11", 43, and his body-fat percentage is 20 percent, his RMR is 1,857 calories.

For example, if a female 130 pounds, 5'3", 36, and her body-fat percentage is 25 percent, her RMR is 1,473 calories.

BMR or RMR can be used to estimate total daily caloric expenditure. According to the American Council on Exercise, after you determine your RMR, based on one of the above equations or an online calculator, you can multiply it by one of the numbers below, called activity factors:

If the man in the above example exercises two days per week, his daily caloric expenditure is roughly 2,384 to 2,481 calories.

If the woman in the above example exercises six days per week, her daily caloric energy expenditure is roughly 2,155 to 2,541 calories.

This calculation gives you the estimated number of calories you burn in one day at your current level of activity; this is how many calories you need to consume per day to stay at your current weight.

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To lose weight, you need a caloric deficit, meaning that you either must reduce your caloric intake below your total daily energy expenditure or increase your total daily energy expenditure, says Greaves. For example, you can try multiplying your RMR by various activity factors to see how your daily caloric burn would fluctuate with increased exercise.