What Are Calories?

Most people have heard about the importance of calories but still don’t fully understand what they are or what to do about calories.

Calories are the energy found in the food we eat that we use to move, breathe, and survive. If you take in more calories than you need in a day, your body stores them as fat to use later. When you consistently consume too many calories for your activity level, you will gain weight. 

It’s important to pay attention to how many calories you’re eating to lose weight and maintain a healthy weight. Keep reading to learn more about calories.

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What Are Calories?

Calories are the energy provided by fat, protein, and carbohydrates. These are known as macronutrients. Your body uses the energy from calories to survive and move throughout the day. The amount of calories you eat and burn in a day influences how much you weigh. 

How Many Calories Should I Eat in a Day?

The number of calories you need varies based on factors like sex, weight, age, height, genetics, and activity level. 

The U.S. Department of Agriculture's (USDA) Dietary Guidelines for Americans 2020–2025 suggests that, on average, females need between 1,800–2,400 calories per day, and males need about 2,000–3,200 calories per day.

Keep in mind that these ranges are general recommendations and don't consider the needs of individuals. 

Talk with your healthcare provider or a registered dietitian if you want help figuring out how many calories to eat in a day. You could use a calorie calculator, like the Body Weight Planner from the National Institute of Health.  

Calories and Weight Loss

If you have a goal to lose weight, you may find it helpful to count calories. Tracking your calories helps build awareness of how much you eat in a day. People are often surprised to find out how many calories they are consuming without realizing it. 

Once you know how many calories to eat in a day, you can keep track on paper or use a tracking app to help you stay on target with your daily goal. 

Multiple factors influence your weight, like genetics, the medications you take, other health conditions you may have, your age, hormone levels, and more. Be sure to talk with your healthcare provider if you have any questions about weight loss. 

Calories Burned During Exercise

Paying attention to how many calories you’re eating is important, but you’ll also want to focus on burning more calories to help you maintain a healthy weight. Your body does use energy while resting for activities such as repairing tissues, breathing, and keeping your heart beating. 

Still, intentionally moving your body helps you burn even more calories.

The Centers for Disease Control and Prevention (CDC) recommends adults get at least 150 minutes of moderate-intensity activity per week and two days of muscle-strengthening activities per week. This could be broken up into 30 minutes per day over five days, with additional health benefits for people who get more physical activity.  

Here are some tips to help you get more exercise each week:

  • Ask a friend to be an accountability partner.
  • Walk during part of your lunch break.
  • Park farther away in parking lots.
  • Take the stairs.
  • Try group fitness classes.
  • Hire a personal trainer.
  • Test different types of workouts to find one you enjoy.
  • Start slowly, and build up your exercise routine over time.

How to Reduce Calorie Intake

If you want to reduce the number of calories you’re eating sustainably, you’ll want to first consider the types of food you eat.

For example, foods high in unhealthy fats and sugar provide large amounts of calories without giving you many vitamins and minerals. These foods also tend to be smaller in volume, which means you may eat more before feeling full.

Aim to fill most of your plate with healthier and more nutrient-dense foods like:

Aim to eat more fiber and protein throughout the day. Both of these are known to help you stay feeling full longer, which may make it easier to eat less.

Potential Risks of Calorie Counting

Calorie counting isn’t an exact science, and it can be easy to overestimate or underestimate how much you’re eating. Instead of focusing solely on calories, you may find it better to emphasize eating a balance of healthy foods. 

If you’re reducing the number of calories you’re eating, be careful not to cut your calories too much. Not eating enough can lead to side effects like low blood sugar, light-headedness, dizziness, and fainting.

Cutting your calories too low could impact your metabolism. A 2021 study found that the body adjusts metabolism to slow weight loss and prevent starvation, which can stall weight loss attempts. 

In addition, a strong focus on dieting and persistent dieting are risk factors for eating disorders. So, be mindful of your mental health and relationship with food when trying to lose weight. 


Calories refer to the energy we get from food and use to live. On average, males need about 2,000–3,200 calories per day, while females need about 1,800–2,400 calories per day. However, the exact amount of calories you need daily depends on your metabolism, body size, genetics, activity level, and other factors.

Tracking your calories, paying attention to the types of food you eat, and exercising regularly help support healthy weight maintenance. 

A Word From Verywell

Calories aren’t a bad thing; in fact, they’re beneficial. All humans need calories to survive and feel good throughout the day. Taking in too many calories by eating too much or taking in too few calories by not eating enough can be harmful.

Try to focus on eating a balance of nutrient-dense and healthy foods to support your overall health. If you’re looking for more help understanding calories, talk with your healthcare provider or a dietitian to learn more.

Frequently Asked Questions

  • What are empty calories?

    "Empty calories" is a term used to describe foods that provide a large number of calories, while containing little nutritional value (like vitamins and minerals).

  • What food has zero calories?

    There are no foods that are truly zero calories. Water is the only thing people consume that doesn’t provide any calories.

    Very low-calorie foods are often considered “zero-calorie” foods because, in theory, the energy it takes to digest them is more or equal to the calories they provide. Examples of very low-calorie foods include celery, cabbage, lettuce, broccoli, brussels sprouts, and apples.

  • How many calories should you eat to lose weight?

    You should aim to eat about 500 calories less than you expend in a day to support weight loss of 1 pound per week. For most people, this would put them in the range of around 1,500–2,000 calories a day. But the right amount for you depends on how active you are, your age, your sex, your body size, genetics, and other factors.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Department of Agriculture. Dietary Guidelines for Americans 2020–2025.

  2. Centers for Disease Control. How much physical activity do adults need?

  3. Hervik AK, Svihus B. The role of fiber in energy balance. J Nutr Metab. 2019;2019:4983657. doi:10.1155/2019/4983657

  4. Moon J, Koh G. Clinical evidence and mechanisms of high-protein diet-induced weight loss. J Obes Metab Syndr. 2020;29(3):166-173. doi:10.7570/jomes20028

  5. Martínez-Gómez MG, Roberts BM. Metabolic adaptations to weight loss: a brief review. J Strength Cond Res. 2021 Mar 3. doi:10.1519/JSC.0000000000003991

  6. Loth KA, MacLehose R, Bucchianeri M, Crow, S, Neumark-Sztainer D. Predictors of dieting and disordered eating behaviors from adolescence to young adulthood. Journal of Adolescent Health. 2014;55(5):705-712. doi:10.1016/j.jadohealth.2014.04.016

By Ashley Braun, MPH, RD
Ashley Braun, MPH, RD, is a registered dietitian and public health professional with over 5 years of experience educating people on health-related topics using evidence-based information. Her experience includes educating on a wide range of conditions, including diabetes, heart disease, HIV, neurological conditions, and more.