How Many Calories Should You Eat in a Day?

Updated: Mar. 26, 2021

Don't eyeball it, calculate it.

What are calories?

People throw around terms like “low calorie,” “zero calories,” and “calorie-cutting” all the time, but do you have a good sense of how many calories you actually need? Despite everyone looking to shave calories, you can definitely go too far. “Calories are a unit of energy,” says Alex Robles, MD, of The White Coat Trainer in New York City. “They serve as fuel to allow your body to perform all of its necessary functions. This includes movement such as walking, running, and carrying groceries, and automatic functions such as breathing, food digestion, and blood circulation. Almost every single thing that is edible contains a certain number of calories.” 

Calories come from fat, carbohydrates, and protein. Any calories your body doesn’t use are stored as fat where, if your body should run low on ready calories, they can be converted to energy, explains Susan Besser, MD, of Mercy Medical Center in Baltimore, Maryland.

So how many calories should you eat a day?

How many calories do you need? There’s a formula to find that out. According to Besser, the average adult needs about 2,000 calories a day. If you’re trying to lose weight, you should cut 500 calories. But there’s a more precise method for figuring out how many calories you should eat in a day by establishing your basal metabolic rate (BMR) and then adding in your activity levels. Your BMR is the number of calories your body burns just to meet your basic functions (keeping your organs functioning and your muscles fed, for example). 

To calculate your BMR, fitness trainer Nick Page of The Trainer Page in Holbrook, New York, recommends the Harris-Benedict Formula; you can calculate it online or do the math yourself with these equations.

For men: 66 + (6.24 x weight in pounds) + (12.7 x height in inches) – (6.8 x your age) = BMR

For women  655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x your age) = BMR

Next, multiply the number based on your how active you are throughout the week:

  • Little to no exercise: BMR x 1.2
  • Little exercise (engaging in sports or workouts one to three times a week): BMR x 1.375
  • Medium exercise (sports or workouts three to five times a week): BMR x 1.55
  • Hard exercise (sports or workouts six to seven times a week): BMR x 1.725
  • Intense exercise (sports or physical job or training two times a day): BMR x 1.9

If you maintain your activity level, you now have a good sense of how many calories you need to stay at your current weight—just remember that you want to make sure you get those calories from nutritious, colorful foods—not bland, high-carb, low-nutrient sources like junk food, says Besser. If you’re planning to shed some pounds, here’s how to determine the calories you need for your weight loss goal. And, if you’re curious, here’s how many calories are in a pound and what it really takes to lose one pound in a week.

How to burn calories and reduce your intake

The most effective way to burn more calories is to simply get moving,” says Stephen Campolo, Flx Body Fitness fat loss and nutrition expert. “Even if it’s just going for a 30-minute walk or riding your bike. Any time your body is in motion you are burning calories. Start where you can and as you progress you can begin to implement weights or a steady workout routine.”

Campolo also recommends tracking your calories to better understand what you’re eating and reduce your intake. There are several apps you can download on your phone which will scan bar codes and enter what you eat and calculate the calories you eat that way. “Most people greatly underestimate how much they are eating, so tracking this will give you a good idea of how many calories you are actually consuming,” Campolo said.

This, combined with exercising, can help you lose weight. But it’s important to remember you need calories to function, no matter how much weight you’re trying to lose. Want to see where you can cut excess calories? Here are 100 easy ways to cut 50 calories throughout your day.