How many calories you need in a day was a top-searched Google question in 2019 so I figured it was worth reviewing for you so you don’t have to hunt down the answers!
Before we get into the question of how many calories you need in a day, let’s start with what calories are and what you need to know about them. I know you’re already familiar with the idea of calories, but essentially, a calorie is a unit of energy, so when you’re assessing how many calories you need each day, you’re assessing how much energy your body needs to keep you alive. Most people wonder about calories in relation to their weight. I’ve found that calorie awareness—understanding the range that will help you either stay steady or gain or lose weight—is helpful, but I don’t recommend fixating on calories. Here’s what you need to know.
How many calories you need in a day depends on multiple factors.
Your gender. For the most part, men need more calories than women, largely because they are taller and have more muscle mass.
The amount of muscle mass you have. I just hinted at this, but muscle is more metabolically active than other body tissues (like fat) so a 5’5’’ female body builder will likely need more calories than a 5’5’’ woman who takes spin a few days a week.
Your age. Muscle tissue naturally declines over time, so once you hit your late 30s, you may begin to notice that you can’t eat what you used to eat and maintain the same weight. This is a normal process of aging so in order to keep your weight steady, you will either need to eat fewer calories or offset the decline by building muscle mass through strength training exercises.
Your activity levels. Are you killing it at the gym six days a week or working on your feet? Both will impact how many calories you need in a day. Anything you do that involves more than sitting at a desk or sleeping will impact your calorie needs.
Non-exercise activity thermogenesis or NEAT for short. This is actually really NEAT! You burn calories doing non-intentional things, including fidgeting, folding laundry, and using a standing desk. These activities account for up to 20% of the calories you burn and therefore, have an impact on the calories you need in a day. Every little bit of NEAT activity adds up, and one small study found that these types of movements added up to burning an extra 800 calories per day (which would then boost your calorie needs by that amount). (1)
Genetics. Genetics plays a role in how many calories you need in a day because some bodies are naturally programmed to be larger in some sense—some are taller, some have more muscle mass, and some are heavier.
Your weight. For the most part, larger bodies need more calories in a day compared to smaller bodies. So again, men have higher calorie needs than women. Beyond that, when you’re carrying extra weight and go on to lose weight, the calories you need in a day will adjust based on your smaller frame. In other words, you will need fewer calories to accommodate your new body size.
How do you determine how many calories you need in a day?
There are several online calculators that can help you determine this, but my favorite is the Body Weight Planner from the NIH NIDDK. This calculator tells you how many calories you need in a day to maintain your current weight, how many are needed to reach a desired goal (whether higher or lower), and how many you need to maintain your goal weight.
If, for example, you’re trying to lose weight, you’ll see that you’ll need to shave off some calories in order to reach your goal weight and that you won’t be able to revert back to your current calorie level in order to maintain your loss. This is one reason why losing weight can be difficult. On top of the fact that you need fewer calories per day than when you started off, your body’s hunger hormones make some adaptations so you may find yourself hungrier, but in need of fewer calories. This poses very real challenges, which is why it’s a good idea to work with a dietitian who can help you develop food and lifestyle strategies to cope with this dynamic. (If you want to chat about how I can help, click here to schedule a complementary call.)
Should you track or count calories?
Not necessarily. I’m all for any tool that is helpful for you and I know plenty of people who like the accountability of tracking, but if that’s not for you, don’t worry! I think having calorie awareness is helpful, but it’s actually more important to focus on the quality of your calories.
In one study that put people on either a low carb or low fat diet, there was no significant difference in weight loss at the 12-month mark, meaning neither diet was superior to the other. (2) Instead, researchers concluded that eating more whole foods and fewer heavily processed ones, boosting veggie intake, and cutting your sugar intake were the real keys to weight loss.
Another year-long study found that people who boosted fiber intake to 30 grams per day lost about as much weight as others who followed a more complicated diet that involved more of an overhaul. (3) Again, quality over calories.
And finally, for those who think calories are everything, I offer this new study, which found that heavily processed foods prompt overeating and weight gain. (4) In the study, eaters were randomized to receive either heavily processed meals or minimally processed ones for a period of two weeks. Here’s the thing: Eaters went through both parts of the study AND meals were matched for calories, sugar, fiber, fat, and carbs. People were told to eat as much or as little as they liked. On the processed foods phase, they ate about 500 calories more, they ate faster, and their hunger and fullness signaling was off. Over the two week study period, they gained 2 pounds. But on the minimally processed diet, the opposite thing happened. They ate less, filled up, and lost 2 pounds over the two weeks. This is pretty good evidence that the quality of your calories makes a huge difference!
I like to make this analogy: If you’re only looking at calories and ignoring where those calories are coming from, it’s like buying a car off the internet. You might like the color, make, and model, but you don’t know if it’s a lemon until you look under the hood and give it a test drive.
Should you exercise more to burn more calories?
This isn’t a trick question! The truth is, exercise doesn’t burn as many calories as you think and even your fitness tracker can be off. A Stanford university study found that your Apple watch and other devices are pretty reliable at measuring your heart rate, but less so for measuring the amount of calories you burn through exercise. According to the test of seven devices, the most accurate—the one that measured best—was off by an average of 27%. I’m not a math whiz, but if you think you’re torching 400 calories during an exercise session, the correct amount is probably closer to 300 calories. (5)
I’m raising this not to split hairs, but to say that I’m in favor of exercising because you enjoy it, not to burn calories. Sure, it will effectively burn some calories, but in my experience, this isn’t terribly motivating and since it isn’t a good strategy for weight loss, I’d rather see you have a positive movement experience that isn’t all about torching calories or burning off something you ate. You’ll get plenty of health benefits by participating in less strenuous forms of exercise and particularly if you can maintain that activity level over time—something that becomes challenging with super-intense workouts, like HIIT and Tabata.
Who shouldn’t count calories?
Anyone who has had an eating disorder or just a fixation on weight, calories, dieting, or excessive exercising for the purpose of burning calories should avoid counting or tracking calories. When calorie counting takes up too much of your mental space and interferes with a healthy and happy life, it’s better for your wellbeing to avoid it and find more suitable tools to help you live more healthfully.
Also, I work with a lot of people who manage demanding careers and busy lives and the thought of doing ONE. MORE. THING. feels overwhelming and stressful. As I’ve said, tracking what you eat isn’t the only tool in the toolbox so if it feels daunting, there are other things you can do instead.
Who should count calories?
Some people like the accountability that calorie counting and tracking apps provide. If you like this form of monitoring, it can be really helpful for weight management. The key is to make sure that you aren’t eating every last bite just because you have spare calories at the end of the day, and that you aren’t doing calorie math—factoring in what you’ve burned compared to what you’ve eaten. For reasons I’ve explained, calorie math is imprecise, so I only advocate counting calories when used with other approaches.
If you’ve recently been on vacation or a work trip or something else has interfered with your healthy eating habits, a calorie counter may be eye opening. You might find that you’ve gotten used to eating more calories than you need in a day and that can help you determine where to cut back.
Calorie trackers can also help clue you in to gaps in your diet (think not enough veggies) and help you identify micronutrients that might need a lift. For example, if you aren’t getting enough fiber or calcium, a tracker that also lists this information might expose these things.
What else can you do besides tracking calories?
If you’d rather not think about how many calories you need in a day, I’d suggest tuning into your hunger and fullness levels, which can help you discover if you’re eating an appropriate amount for YOU at any given time.
It’s also important to register how food makes you feel. Your body sends you so many signals and hunger and fullness are just a couple of them. Others could be bloating and gas, sluggishness, an increase in energy, constipation, acne, etc. When you pick up on these signals, you can link them to certain foods or eating patterns and then start to eat with more intention.
You can also get healthier by eating more mindfully. To the degree possible, limit distractions, like the TV and computer, when you’re eating. If this isn’t fully possible, do what you can, like put your food down between bites and chew slowly and thoroughly. Always try to register what your food tastes like (think: chewy, savory, creamy, and so on), which helps you form a memory of the eating experience.
When you bring an overall awareness to your eating habits, you can start to take charge and become more in control of your food choices. These types of approaches can help you eat more healthfully whether or not you’re keeping track of your calories.