Old-school calorie counting seems to be back in fashion.
For years, diets like keto, paleo, and "clean eating" reigned supreme, with a focus on limiting specific foods instead of overall food consumption. But according to the International Food Information Council’s Food and Health Survey 2021, counting calories seems to be the most popular way to eat again.
Do men now have to count every calorie to be healthy or reach your fitness goals? Absolutely not.
But is it helpful to have a basic understanding of how your body uses energy derived from food? You bet.
No doubt you have some understanding of what a calorie is. After all, calorie counts are listed on packaged foods and on fast food menus, and it’s hard to have a conversation about nutrition or fitness without mentioning at least a few calories. You may have even tried a popular calorie tracker like MyFitnessPal or Noom.
But do you really know what calories are and why they are so important? And know how many calories you actually need in a day? (We mean the real number, not a general recommendation a weight loss app might spit out.)
Here we go into the true definition of a calorie, as well as what factors affect your energy needs (aka your metabolism) and how to estimate the right calorie count for you.
What is a calorie?
Technically speaking, when we talk about calories, we’re actually talking about kilocalories. According to the U.S. Department of Agriculture (USDA), one kilocalorie is the amount of heat required to raise the temperature of 1 kilogram of water by one degree Celsius.
So calories are a measure of energy. All three macronutrients contain a set number of calories per gram: 4 calories per gram for carbs and protein, and 9 calories per gram for fat. (Alcohol, which is not a macronutrient and has no nutritional value, contains 7 calories per gram.)
In addition to the unique functions of each macronutrient, their calories provide energy that our bodies need to function. We need calories to move around, but also for all the basic bodily functions that occur at rest, from DNA synthesis to hormone production to sending chemical messengers through the body to keep things running smoothly.
How many calories do men need?
According to the Centers for Disease Control and Prevention (CDC), the average American male under 40 is 5’7" and weighs 197 pounds. At a moderate activity level (moderate exercise 3 to 5 times per week), it would be about 2.822 calories per day needed to maintain his weight.
If weight loss is the goal, the USDA says reducing your calorie intake by 500 to 1000 calories per day can result in a safe weight loss of 1 to 2 pounds of weight loss per week. For our average American, that’s between 1.822 and 2.322 calories per day. However, drastically cutting calories can backfire, as you may end up so hungry that you eat too much.
Exercise is also important: If you burn 500 calories a day through physical activity, reducing 1000 calories would actually result in a deficit of 1500 calories, which is too many.
If you’re trying to gain weight, the Cleveland Clinic recommends increasing your caloric intake by 300 to 500 calories per day-3.122 to 3.322 calories per day for the average man, assuming his activity level stays the same.
"The main factors that determine how many calories someone needs are birth sex, age, genetics, body size and daily activity," says Anya Rosen, MS, RD, a New York-based nutritionist. "Other variables can play an important role role, such as body composition, dietary behaviors, injury or illness."
In general, men burn more calories than women because they’re usually bigger overall. Men also tend to have more muscle and less fat mass, which affects calorie burn, explains Kyle Gonzalez, MS, CSCS, a sports scientist and performance coach at Future.
Injury and illness can also temporarily increase caloric needs. Healing severe burns or other large open wounds requires extra energy and protein. Cancer can dramatically increase your calorie consumption. If you have a fever, you need extra calories to compensate for your higher body temperature. Even fighting a cold takes energy.
How to calculate your calorie needs
Although it is possible to estimate how many calories you need in a day, there is a big caveat: "There are many different formulas to determine calorie needs, but all have large margins of error because there are too many influencing variables to control for. " says Rosen.
Scientists use a method called indirect calorimetry to measure exactly how many calories a person burns in a day, but it’s expensive, time-consuming, and fairly inaccessible to most people.
If you’re curious about your exact calorie needs, here’s how to determine them for yourself.
Track your food intake
"I find that the best way for you to determine your caloric needs (assuming you are outside of a research environment) starts with making sure you are currently maintaining your weight," Rosen says.
"Once the weight is stable, track your food intake for 1 to 2 weeks without changing your normal diet. The average calories over that period are a good estimate of your calorie needs, and you can adjust from there according to your goals."
In other words: If your weight doesn’t change, you’re eating the right number of calories.
A metabolic calculator
You can also try estimating your calorie needs using a formula, which is easy with an online calorie calculator from a trusted source. This guide, from the American Council on Exercise (ACE), takes into account your age, weight, gender, height and activity level, from sedentary to very active, to determine your calorie needs.
How muscle mass affects calorie burn?
Muscle burns more calories by weight than body fat, although the difference is not as great as is sometimes claimed. "The claim "muscle burns more calories than fat" is true, but misleading," says Rosen.
The best estimate we have is that one pound of muscle burns six to seven calories per day. "It’s about the equivalent of a slice of cucumber," says Rosen. Fat, on the other hand, burns about two calories in the same period of time. So building muscle increases the number of calories you burn – as does fat gain, albeit to a lesser extent – but not drastically. An extra 10 pounds of muscle mass can only increase your total calorie consumption by 60 calories per day.
In fact, the size of other body parts probably plays a more important role in your daily calorie needs. A 2011 study found that more than 40 percent of differences in total calorie burn between people can be explained by differences in the size of their internal organs.
How does exercise affect calorie burning?
Of course, your activity level plays a big role in your energy needs. It’s not just your workout that burns calories, but also how much you exercise at work and at home. A physically demanding job burns far more calories than one where you sit at a desk for most of the day, and even taking your daily commute by bike or on foot instead of in a car can make a big difference. When determining your physical activity level, it’s important to keep all of this in mind.
And yes, you also need to consider your workouts. "When you’re doing cardio, you’re not only burning calories faster, but you’re also burning more calories overall per exercise session," Gonzalez says. "Strength training," on the other hand, is usually anaerobic (without oxygen) and helps build muscle and boosts metabolism."You’ll burn fewer calories per session, he explains, but your metabolic rate (the number of calories burned) will remain elevated longer afterward. You’ll also build muscle mass, which can slightly increase your calorie consumption and contribute to better health overall.
"A healthy mix of strength and cardio workouts of varying intensity, frequency, duration and type is always best when building your exercise program," Gonzalez says.
Do you need to count calories?
Ultimately, it is not necessary to count calories to be healthy. If you feel good and have a consistent energy level throughout the day, you probably don’t need to worry about calculating your calorie needs because chances are you’ll reach your goal.
However, if you’re worried about eating too few or too many calories, you can better understand your body’s needs by knowing what contributes to calorie burning.