How Many Calories Should You Be Eating Each Day?

With lots of advice online and every person's metabolism working differently, here's how to you figure out the magic number for you.

December 22, 2015
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I use a calorie- and fitness-tracking app. And while I love the mindless plug-and-chug, I was fiddling around with my app the other night to determine how exactly my goals were being calculated. When I realized how nuanced the numbers were, and how variable they might be from person to person, I had a lot of questions–specifically, if I may need to adjust my goals.

I’m all for tracking apps. They’re convenient. They keep you accountable. They’re legit on your phone, which you take with you everywhere. But I’m also all for knowing the process behind creating your health goals, so if something isn’t working for you, you can get to the source.

Let’s pretend for a moment that tracking apps don’t exist (poof!) If that were the case, here’s how we’d track your calorie consumption.

How many calories do you need per day?

There are so many ways to do this. If you look online, it’ll make your head spin. Basically, you need a calculation that takes into account basal metabolic rate (BMR) or the base number of calories your body burns per day just lying around and total energy expenditure when you add movement and exercise into the mix.

These are the basic calculations for men and women:

BMR = 10 * weight(kg) + 6.25 * height(cm) – 5 * age(y) + 5 (man)

BMR = 10 * weight(kg) + 6.25 * height(cm) – 5 * age(y) – 161 (woman)

Or you can simply check a calculator. From there, you need to add in your energy expenditure, which looks a little something like this and requires your best guess for average activity level:

– Sedentary (little or no exercise) = BMR x 1.2

– Lightly active (light exercise or sports 1-3 days a week) = BMR x 1.375

– Moderately active (moderate exercise or sports 3-5 days a week) = BMR x 1.55

– Very active (hard exercise or sports 6-7 days a week) = BMR x 1.725

– Extra active (very hard exercise or sports + physical job or training twice a week) = BMR x 1.9

Or you can use a calculator to check yourself. Keep in mind, this is the nitty-gritty scientific way, and even then it’s not 100 percent accurate. Everybody is different, and each person’s metabolism works at a pace that’s very specific to them, based on factors like activity level, metabolism, and lean muscle mass.

With that in mind, a lot of experts and registered dietitians I know briefly put a pencil to paper when determining how many calories their patients need each day using a quick-and-dirty method. So I asked one–Natalie Stephens, a dietitian at The Ohio State University Wexner Medical Center–to share how she does it in her practice.

“I go with a starting point of 25 calories per kilogram,” she explained. “So if you’re 150 pounds, you’d divide by 2.2 to get 68 kilograms, and you’d need about 1,700 calories per day. You have to have the patient try this and check back in a month to see their progress.” Because, again, not everybody burns the same. So if you’re not getting the results you want, or you’re losing instead of maintaining your weight, you may need to make some slight adjustments.

How do you determine how many calories you should be eating to lose weight?

If you’re looking to maintain your weight, the above calculation is enough. You’re done! Just use that figure (BMR + total energy expended) as your calorie baseline. Yay.

But lots of people who are tracking intake are actually looking to lose weight. This means you’ve got to shave some calories.

One pound of weight loss per week is generally considered a safe and surmountable goal. To meet it, you need to create a deficit of 3,500 calories per week, which is 500 calories daily. You can do that any way you’d like, but cutting a huge chunk of calories from your diet or becoming a gym rat is usually a quick way to fall off the weight loss wagon.

Stephens suggested this: “Ideally, the patient will cut dietary calories down by 250 calories and increase their exercise to burn 250 calories,” she said. “That way they’re not doing anything so drastic they can’t maintain that behavior in the long run.”

This is where a calorie-tracking app becomes huge. You can figure out exactly where you should cut your calories. If you can swap your soup and sandwich for a salad, nix cheese on your baked potato at dinner, and remove part of your morning snack to eliminate 250 calories? Cool. If that seems doable, then do it! Focus on what’s least important in your diet or what you can lose, while still keeping things relatively balanced (read: don’t cut a whole food group, because you’re #JustNotThatIntoGrains).

At the same time, you need to sweat out around 250 calories per day, too. Harvard Health has a pretty amazing chart for calories burned in 30 minutes during tons of different exercises based on three different body weights, which you can multiply if you need an extra exercise bump. So maybe 250 calories for you is 45 minutes of walking or 30 minutes of basketball. (You get the idea.)

That bit about 1,200 calories…

If you want to lose weight faster than that, you can feasibly lose one to two pounds per week. Simply adjust your calorie goals accordingly.

That said, you may have heard that you should never, ever consume fewer than 1,200 calories per day. For the average person, here’s why that warning exists: “If you’re eating less than 1,200 calories a day, it’s not possible to get the minimum recommendations from each food group,” said Stephens. “This means, in the long run, you’re bound to have deficiencies that will impact your long-term health.”

So, be smart. Losing weight is not worth sacrificing your long-term health or creating disordered eating habits.

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