Very basic answer: Here is a calculator that can give you a rough estimate of how many calories you should eat based on your goals (gain weight, lose weight, stay the same weight).
You need to put in your age, weight, height, sex, and activity level.
BUT HERE’S THE THING, and it’s super important: This calculator may not really work for you. So next up is an explanation about what this calculator is doing, and also 10 important things you should know about your metabolism and calories that can help you personalize this answer a bit more.
First, let’s talk about what it means to say you ~should~ be eating a certain number of calories per day.
That’s referring to an ideal number of calories, based on a lot of different factors that are outlined below. There’s no moral judgment attached to it, though. The number of calories anyone eats is a personal decision, and not at all a reflection of their intelligence or value as a human. You can and should do whatever you want with your body. This article is just meant to be a guide for people who may find it helpful in achieving certain goals.
It isn’t for everyone, though. If you have a history of disordered eating, for example, you should work with your doctor to figure out what’s best and healthiest for you to focus on when it comes to calories and nutrition and food. That might mean not thinking about calories at all. Again: It’s personal.
OK. So if you do want to figure out how many calories you should eat, a good place to start is by determining your basal metabolic rate, or BMR.
This isn’t how many calories you should eat in a day! This is just step one: “BMR is how many calories you’re burning if you’re lying in bed doing nothing, having eaten nothing for the last 12 hours,” Dr. Michael Jensen, endocrinologist, professor of medicine at Mayo Clinic, and body weight regulation and obesity specialist, tells BuzzFeed Life. It’s the minimum number of calories your body needs to simply ~exist~ — basically, to keep your organs running. (Most people typically move a bit more than that, which is why you need to eat a bit more than this. More on that in a minute.)
There are a few different ways to calculate BMR, but most experts use what’s called the Mifflin-St. Jeor Equation, New York City-based dietitian Brittany Kohn, MS, RD, tells BuzzFeed Life. This equation takes into account your sex, age, weight, and height. It’s different for men and women. It stands to reason that trans individuals who have NOT medically transitioned may be able to use these equations by choosing the sex that they were assigned at birth (so, a trans man who has not medically transitioned would use the female equation, and vice versa). Unfortunately, it’s unclear how these equations apply to transgender individuals who have medically transitioned.
Here’s the equation for men:
BMR = 10 x weight (in kilograms) + 6.25 x height (in centimeters) - 5 x age (in years) + 5
And here’s the equation for women:
BMR = 10 x weight (in kilograms) + 6.25 x height (in centimeters) - 5 x age (in years) - 161
That’s a lot of numbers, so here is a calculator that can figure out your BMR for you.
Once you figure out your BMR, you then want to figure out how many extra calories you use every day, based on how active you are.
The total calories you use each day (through ~existing~ and also through moving around and working out) is called total energy expenditure, or TEE. This is the number that can help you figure out how much to eat, based on your goals.
The more active you are, the more calories you use each day. There’s an equation for that, too — you should multiply your BMR by a certain number that corresponds to how active you are. Kohn broke it apart for us in an email:
• sedentary (little or no exercise) = BMR x 1.2
• lightly active (light exercise/sports 1–3 days/week) = BMR x 1.375
• moderately active (moderate exercise/sports 3–5 days/week) = BMR x 1.55
• very active (hard exercise/sports 6–7 days a week) = BMR x 1.725
• extra active (very hard exercise/sports and physical job or 2x training) =
BMR x 1.9
Those are also a lot of numbers to look at again! But don’t worry. Here is a calculator that will find your TEE for you.
It’s the one we linked to all the way at the top.
Once you know how many calories you use each day, you should think about what your goals are.
It’s (obviously) more complicated than this, but here are some general rules:
To stay the same weight, eat the same number of calories that you’re burning.
To gain weight, eat more calories than you’re burning.
To lose weight, eat fewer calories than you’re burning.
How much more or less? Well, 1 pound = roughly 3,500 calories. So to gain a pound you’d need to eat an extra 3,500 calories over what you typically burn, and to lose a pound you’d need to eat 3,500 calories less than you typically burn.
If you want to gain weight, you should talk to your doctor or a registered dietitian about how to do it in a healthy and targeted way.
If your goal is to build muscle and bulk up, for instance, the macronutrients in the foods you’re eating matter just as much as how many calories you’re adding to your diet. Eating milkshakes all day every day will help you gain weight, but you won’t feel very good as it’s happening. (On a related note, you might find some helpful tips in this story: 11 Ways To Build Muscle And Lose Fat.)
And if you want to lose weight, a healthy way to do that is to aim for losing no more than 1 or 2 pounds a week.
Since 1 pound = 3,500 calories, in order to lose 1 pound a week, you’d need to have a weekly calorie deficit of 3,500 calories, Kohn says. That means you’d need to eat 3,500 calories fewer than you’re using throughout the week.
Kohn says that you can do this by having a 500-calorie deficit each day (meaning you burn 500 more than you eat), or by cutting about 300 calories from your daily diet and then making up the other 200 calories with extra exercise.
This calculator can help you figure out how many calories you’ll want to eat if you want to lose 1 or 2 pounds per week.
Again, it’s the one we linked to at the very top.
NOW. Everything written above are very basic guidelines for how to determine your daily calories. But you should know: This is all based on ESTIMATES. Your mileage may vary, depending on a lot of stuff.
Here are a few more things you should know about your metabolism, caloric intake, and how many calories you may want to be eating:
1. The BMR equation we mentioned above is just an estimate — so it’s not going to be totally accurate for a lot of people.
“In general, for most people, if you do one of these online calculators, you’re probably going to be within 10% of what it says,” Jensen says. “So if it says 1,600 calories a day, it could be 160 in either direction.”
And that’s for people who fall within a standard and predictable metabolic range. “About 10% of people will have a metabolic rate substantially higher than you would predict, and another 10% of people are going to be quite a bit lower than you predict,” Jensen says. “It might be about 20% less or 20% more.”
2. BMR estimates also don’t consider your body fat percentage, or if you’ve got a lot of muscles.
“The more lean tissue you’ve got, the more calories it takes to keep going, even if you’re just lying in bed doing nothing,” Jensen says. Lean tissue applies to your organs like your liver, heart, and kidneys, and it also refers to your muscles — your muscles use more calories during the day than your fat does. “Fat is the lowest-burning tissue in the body,” Jensen says.
This is why the BMR estimates are different for men and women — in general, men tend to have lower body fat percentage than women do. “If you have a man and a woman who both weigh 70 kilograms, on average the man is going to have less fat and more lean tissue,” Jensen says. “So even at the same weight, men are going to tend to burn more calories when they’re lying around doing nothing. They don’t have as much body fat.”
Even with sex taken into account, though, the BMR estimates aren’t going to be super specific on an individual level.
3. You can get a better, more personalized sense of how many calories you typically burn by tracking what you eat, how much you exercise, and how much you weigh.
“The most accurate measures of metabolism are special breathing apparatuses that measure oxygen consumption to determine BMR,” Kohn says. “Most people aren’t spending the time and energy to do one of these tests, so the best way for someone to get a better understanding of their metabolism and caloric needs is to keep track of things: what you’re eating, what you’re doing (physical activity), and your weight. Seeing what direction your weight is moving (or not) as a result of what you’re eating and what physical activity you’re doing will help determine what changes to make in order to see your desired results. That combined with [some of the calculations we’ve covered here] will give a good picture of what’s going on in your body and how to reach your goal.”
There are lots of services that can help you do this — MyFitnessPal and LoseIt, to name a few. You may also want to find a good heart rate monitor, which does a good job of looking at your heart rate, age, sex, and activity to estimate calories burned. Polar makes some great heart rate monitors.
4. It’s really hard to eat less than 1,200 calories a day and still be healthy.
“It’s hard to get in a balanced nutritional intake with less than 1,200 calories a day,” Jensen says. “You’re just getting in so little food that to get in a reasonable balance that we all need between vitamins, minerals, fibers and all that stuff, if you’re chronically under 1,200 calories a day, it’s pretty tough to meet your nutrient needs.”
5. The general idea of counting calories also doesn’t take into account the TYPE of food you’re eating. And it matters.
“The thing about your metabolism is that there’s a lot of factors going into how efficiently you’re taking in calories and burning them, and now we’re finding out that the kind of calories you’re taking in are also important,” James LaValle, clinical pharmacist, board certified clinical nutritionist and author of Cracking the Metabolic Code, tells BuzzFeed Life. “The more nutrient dense and less calorically dense with your diet, the better off you’ll be. If you’re choosing the wrong foods, and you’re not getting the nutrients you need, you lead your body to a process over time of chronic inflammatory signaling that alters your metabolism.”
What this means: Eat lots of vegetables and fruits. Limit your carbohydrate intake, and choose complex carbohydrates over simple carbs. And, as he said, choose foods with a LOT of nutrients per calorie — so, typically whole foods, lots of produce, foods with protein, fiber, and healthy fats to help you feel full for longer and minimize cravings, and as little added sugar as you can manage. (You may want to check out this primer for 14 Ways To Eat Less Sugar, if it helps.)
6. Most people aren’t great at knowing how many calories they eat on a regular basis, especially if they try to do it by memory.
“It’s amazing how bad we are at remembering and estimating how much we eat in a day,” Jensen says.
One way to help yourself out in this arena is to keep a food diary for a few days, Kohn says. “The most important thing I have my clients do is keep food journals,” she says. “This gives me a great window into their lives and helps me to know where to start when making changes to their diets.” Even if you’re not going to a nutritionist for help, it can also give YOU a good idea of what kind of foods you’re eating, what food habits you might have (say, snacking in the mid-afternoon), and how you might be able to swap out low-nutrient-dense foods with healthier options.
7. Burning more calories is easier than you might expect, actually.
Here are some examples that Kohn offered:
Brisk walking burns about 100 calories in 30 minutes.
Yoga or Pilates can burn about 100 calories in 30 minutes.
Using the elliptical trainer or stationary bike can burn about 200 calories in 30 minutes.
Running or jogging at about a 10-minute mile pace can burn about 300 calories in 30 minutes.
(Again, these are rough and general estimates.)
8. If your goal is to lose weight, there are other things that can make it REALLY hard.
Lack of sleep and chronic stress are two big ones, LaValle says. Research shows that when you don’t get enough sleep, your body naturally craves high-calorie, high-fat foods. And stress can also cause food cravings. Both of these things can make counting calories and making healthy food choices much, much harder.
Here are 18 things you should know about being sleep deprived, including how to get better sleep.
9. You should also be aware of some other things that might impact your metabolism.
If you take up weight training, for instance, and you build up a lot of muscle and lose fat, you might not lose any weight at all but you’ll be burning more calories throughout the day than you used to — thanks to those muscles.
And certain diseases can also raise or lower your metabolism. Thyroid disease, for instance: Overactive thyroid can raise your metabolism, and underactive thyroid can lower it.
It’s also worth mentioning here that if you’re trying all this stuff and still feeling confused about your results (or suspect that your metabolism is WAY lower than it should be, based on all the things we’ve covered here), you may want to see a specialist, like an endocrinologist, who might be able to measure your metabolic rate and run some other tests to see what’s going on.
10. Bottom line: When it comes to having control over your weight (whether that’s maintenance, gain, or loss), a LOT of stuff can have an impact.
This is a lot of information, which can feel overwhelming. But the most important thing is to think about how to incorporate these tips into your life in a way that’s sustainable and smart and won’t make you miserable. Be patient with yourself. And in the meantime, do what you can to eat healthy foods, move more, get good sleep, and lower your stress.
This post has been updated for clarity.
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