# How much do you actually need to eat to maintain your weight? These tools can tell you.

April 26, 2016

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If you live in the United States, you're probably used to reading food labels that invoke the "2,000 calorie diet." The FDA started using this number as a point of reference for nutrition information decades ago. As a result, many Americans assume that 2,000 calories is the sum that adults should aim to consume in order to stay healthy. However, the actual number of calories that you need to maintain or lose weight can vary tremendously depending on your build, gender, and level of physical activity.

But you don't need to guess or crunch numbers to find your personal calorie needs anymore. It's simple to find out your personal daily calorie target for health maintenance, weight loss, or even weight gain, thanks to free online calculators like this Mayo Clinic Calorie Calculator and this USDA Body Weight Planner. Click on either of these links to quickly estimate how many calories you need daily to maintain your weight.

Ironically, the famous 2,000-calorie diet is not the average daily requirement for an American adult, of either gender or even of both genders combined. And even if it were the average requirement, it's common for group averages to describe relatively few individual members of the group. In fact, the FDA originally wanted to use a higher number (2,350 calories), but instead opted to use the current figure in an effort to discourage overconsumption and simplify the daily-value-percentage math for the public.

Thanks to scientific metrics like the periodically-updated Harris-Benedict Equation and Dietary Reference Intakes, it's now easy for individuals of all descriptions to get a reliable estimate of the number of calories they need to munch daily in order to keep their weight. The Mayo Clinic calculator, for example, draws on both of these models to produce its results. One of the most striking things about using it is seeing how dramatically your level of physical activity affects your daily calorie requirement. For instance, a 30-year-old woman who stands 5'4" and weighs 135 pounds and who leads a sedentary lifestyle would require only 1,700 calories a day to maintain her weight. By contrast, if the same woman started spending lots of time at the gym and developed a very active lifestyle, she'd need 2,350 to maintain her weight:

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Likewise, a man of the same age who stands 5'9" and weighs 175 pounds would require 2,200 calories a day to maintain his weight if he lived a sedentary lifestyle. If he got way into fitness and started exercising strenuously most days of the week, though, he'd need a whopping 3,100 calories to keep the pounds on:

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The table below will give you a better sense of how physical size, age, and gender may affect your daily calorie requirements. These figures were all calculated using the Mayo Clinic calculator, assuming that each "person" leads an active lifestyle (i.e., performs 20 minutes of vigorous exercise about 3 days a week):

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But suppose that you want to gain or lose weight, rather than maintain your current size. It's possible to model what you need to do to hit your target weight with surprising specificity, using the USDA Body Weight Planner's Expert mode. (Click the "Switch to Expert Mode" button near the top right corner of the screen to access these options.)

For example, imagine that our 175-pound, 5'9" man wants to drop 5 pounds over the next month. He's moderately active, but doesn't go nuts in the gym. In order to aid his weight loss efforts, he decides to add 20 minutes of light jogging to his routine, three days a week. Using the built-in estimation functions in the Body Weight Planner, his plan would look like this:

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Surprisingly, this plan would only require him to drop about 400 calories from his diet every day in order to hit his target. After dropping the weight, he could just about return to his original 2,800-calorie maintenance intake.

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The Body Weight Planner even creates charts that project his weight on a daily basis throughout his weight loss effort:

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Of course, it's always easier to say you're going to change your dietary and exercise habits than it is to do it. We're currently working on a tool designed to help people change these aspects of their behavior, as well as other long-term personal habits. Keep an eye out for more news from us on that front!