We Asked an Expert How Many Calories You Need in a Day, and the Answer May Surprise You

If you asked 10 people how many calories you should eat in a day, you would probably get 10 different responses (and be even more confused than when you started). It's not an easy question, yet everyone seems to think they know the answer. Instead of turning to an online macro calculator or fitspo Instagrammer, I took this question straight to an expert, Dr. Preeya Alexander.

Dr. Alexander, also known as The Wholesome Doctor, is an Australia-based general practitioner who is passionate about prevention and enjoys a glass of wine with her healthy meals every once in a while. She gave me the lowdown on how to really figure out how many calories you need in a day, and her answers may surprise you.

If you've ever picked up a fitness magazine, you've probably seen headlines like "Eat 1,200 Calories a Day to Lose Weight Quick!" or "1,200 Calorie Jump-Start Diet." According to Dr. Alexander, however, there is no certain calorie intake that is right for everyone; how many calories you need varies based on a number of factors (so please don't fall for those lose-weight-quick starvation diets).

In medicine, energy is often measured in kilojoules (as opposed to calories), and 8,700 kJ per day is a common baseline. This is roughly the equivalent of 2,000 calories per day, a higher number than you might expect. The mistake so many of us make, though, is thinking of food intake only in terms of weight loss or weight gain.

The food we eat does so much more than that — we need the nutrients from food to fuel every single thing happening in our bodies all day long. This includes things typically associated with food like digestion and energy for exercise but also for hormone production, brain function, disease prevention, and countless other processes.

How many calories you need in a day can vary quite a bit based on your age, sex, and level of physical activity. According to Dr. Alexander, there are many factors that can make that baseline number go up or down. Children and teens, for example, "require extra energy to grow and develop," she said. Men typically need more calories than women because they have more muscle mass, and, according to her, muscle requires energy to function. No matter your sex, the more physically active you are, the more calories you need to replace the energy you burn during exercise (or a physically demanding job). Pregnant and breastfeeding women also need additional calories to support the growth of their baby and milk production.

In order to know if you are truly getting the calories you need, Dr. Alexander recommends you look at a few key factors:

If you're not sure, getting the answers to these questions is as easy as scheduling a wellness exam with your general practitioner. They can help you determine if your calorie intake is right for your needs and lifestyle.

Oddly enough, Dr. Alexander advises her patients to take the focus away from calories and instead look to food quality and upping their physical activity. She said, "It can become an obsessive counting ritual. . . . So I often try to focus on how to change their diet to make it healthier while bumping up their physical activity." Eating healthy whole foods tends to slightly decrease calorie intake (a handful of almonds is certainly more nutritious than a handful of marshmallows), while increasing exercise naturally ups calorie expenditure. When you combine these two things, the result is often slow, steady, sustainable weight loss.

Bottom line, if you feel great, your doctor is happy, and you eat mostly whole foods (and the occasional glass of wine, if you choose), you are probably getting just the right number of calories for you.