What are calories and how many do you need? (2024)

Calories are undeniably listed everywhere – from food labels to restaurant menus, recipe blogs, food tracking applications and even news headlines. All the talk about calories may make you wonder why they are so important. Better yet, what exactly are calories and how do they work? Or maybe you have a general understanding of what a calorie is, but you're not sure how many you should consume in one day. Wherever you are in your calorie knowledge, you'll learn more here. In this article, we explain what defines a calorie, factors to consider when determining your unique calorie intake, the relationship between calories and body weight, and the basics of calorie counting.

Understand calories

Every time you sit down to enjoy a meal, every food and drink contains energy locked in chemical bonds. Once the food or drink is consumed, it is metabolized or broken down by your body to release the stored energy. Your cells then capture this released energy and use it to power the normal body functions needed for survival. To measure the energy gained and used from food and drink, we use a unit called a calorie. In other words, a calorie is simply a standard unit for measuring energy.

Here's a little science background you may not be aware of. The term 'calorie' is technically defined as the amount of energy required to increase the temperature of 1 gram of water by 1 degree Celsius, perNational Library of Medicine. But the calories we use when we talk about the amount of energy in what we eat and drink are actually kilocalories or kilocalories, a unit equal to 1,000 calories. Kcal is the most suitable unit of measurement for foods and drinks, because a large amount of energy is stored in their molecules. It's easier said than donea medium bananacontains 105 kcal than 105,000 cal. However, in general, non-scientific usage, we use 'calories' to mean 'kilocalories'. So we say banana has 105 calories.

Almost everything we consume has some calorie count, and these calories come from three energy sources: carbohydrates, proteins and fats.

Macronutrient calories per gram:

• Carbohydrates:4 calories per gram
• Cool:9 calories per gram
• Egg white:4 calories per gram

Carbohydrates

Of the three macronutrients that provide energy,Carbohydrates often get a bad rap. But when you eat carbohydrates, your digestive tract breaks them down into a sugar called glucose – the main fuel source for your brain, red blood cells and nervous system. Depending on the number of sugar molecules they contain, carbohydrates can be classified as eithersimple or complex. Simple carbohydrates, found in table sugar and fruit juice, can be easily broken down and used for energy, but they can also cause a rapid rise in blood sugar levels. Simple carbohydrates are also present in whole fruits. But because whole fruit is packed with dietary fiber, the sugar is broken down more slowly. Complex carbohydrates, found in unrefined whole grains, legumes and vegetables, are also broken down more slowly, providing longer-lasting energy. For every gram of carbohydrates consumed, 4 kcal of energy is produced.

Fats

Dietary fat plays a central role in protecting vital organs, insulating the body, producing hormones and helping absorb vitamins A, D, E and K, according to a 2019 article inAdvances in nutrition. They can also be broken down and used as an energy source. Although carbohydrates are the body's preferred source of energy, fats are more densely packed and store greater amounts of energy in less space. Therefore, fats are the body's most important long-term energy storage molecules. When excess calories are consumed, they are actually stored in adipose tissue (fat). One gram of dietary fat contains 9 kcal of energy – making fat the macronutrient that provides the most energy. The higher amount of energy in fat is useful during prolonged, light to moderate activities, such as a brisk walk or cycling. Foodsrich in nutritious dietary fatincludes butter, eggs, oily fish, avocado, oil, nuts and seeds.

Egg white

Although energy can be extracted from itegg whiteThe body prefers to use this macronutrient to repair tissues, synthesize immune-protective antibodies, create enzymes, produce hormones, balance pH, and transport nutrients in and out of your cells. This means that proteins are rarely used as an energy source. To reserve proteins for their primary functions, carbohydrates and fat are first used as fuel. Therefore, consuming adequate amounts of carbohydrates and fats is essential to prevent protein from being converted into energyUC Davis Library. But if the body doesn't get enough calories from carbohydrates and fats, proteins can be broken down to provide 4 kcal per day. grams consumed.Protein-rich foodsincludes meat, eggs, dairy products, legumes, nuts and seeds.

How many calories do you need?

According to2020-2025 Dietary Guidelines for AmericansThe total number of calories an adult aged 19 to 59 needs daily ranges from 1,600 to 3,000 kcal. More specifically, adult females need about 1,600 to 2,400 kcal per day, while adult males need about 2,000 to 3,000 kcal per day. Of the total calories consumed, 45% to 65% should come from carbohydrates, 20% to 35% from fat and 10% to 35% from protein. To determine your individual calorie needs, it is important to consider the following factors.

Basic metabolic functions

Your body requires a minimum number of calories to perform the essential metabolic functions that sustain life. These basic functions include respiration, circulation, cell production, protein synthesis, nutrient processing, and ion transport. The minimum number of calories required to fuel these activities is called your basal metabolic rate. BMR is responsible for 60% to 75% of your body's total energy expenditure, according to a 2019 article published inEncyclopedia of animal cognition and behavior. Several factors influence the BMR, such as age, height, weight, body size, body composition, body temperature, climate, gender and hormone status. Therefore, calorie needs are unique for each individual.

Exercise

Another important component of energy expenditure is exercise. Calorie needs vary depending on the type, duration, frequency and intensity of physical activity. For people who make exercise a regular part of their routine, energy needs should be sufficient to fuel and maintain muscle mass. People with larger amountsmuscle mass tends to burn calories faster. On the other hand, those who are physically inactive and have less muscle mass burn calories more slowly. Therefore, strength training exercises can help increase the rate at which calories are burned.

Other factors to consider

The ever-changing stages of life also affect your calorie needs. During pregnancy, more energy is needed to support the growth and development of an unborn child. According toAmerican College of Obstetricians and Gynecologistsneed 340 to 450 calories daily during the second and third trimesters of pregnancy. However, the opposite can be true as we get older. In the last years of life, calorie needs may decrease due to less physical activity and reduced muscle mass. That is why it is important to maintain sufficient muscle mass as you get older. Specific medical conditions can also increase or decrease calorie needs. Your gut microbiome can also influence the number of calories you get from food.

Working with your doctor or a registered dietitian is the best way to identify your calorie needs at all stages of life.

What do calories in food mean?

Certain foods may contain the same number of calories, but not all sources of calories are equal. When looking at the number of calories in a particular food, it is also important to assess its overall nutritional value.

High-calorie vs. nutritious

A food or drink that is considered high-calorie contains a large number of calories per serving. part; some of these foods are also low in nutrients. According toAmerican Heart AssociationThese foods are often high in saturated fat, added sugars and sodium. Several examples of low-calorie and nutrient-poor foods include cakes, pastries, sweets, sugary drinks, fried foods and highly processed meats.

Conversely, nutrient-rich foods contain high levels of nutrients, such as vitamins, minerals, fiber and phytochemicals, and sometimes with fewer calories. Nutritious foods include fruits, vegetables, whole grains, legumes, nuts, seeds, dairy products, fish and unprocessed lean meats. These foods provide important nutritional components for good health.

The key to creating a well-balanced diet is choosing foods that are rich in nutrients and limiting high-calorie foods that are also low in nutrients within your calorie needs.

What is the connection between calories and body weight?

While there are several factors to consider when managing weight, calorie intake plays an important role. To maintain a stable body weight, the amount of calories you consume should be the same as the amount of calories you expend through basic metabolic functions and exercise. But if you want to lose or gain weight, you need to take this into account.

Weight loss

To support weight loss, it is important to consume fewer calories than you burn, also called a calorie deficit. A calorie deficit can be achieved by reducing your calorie intake or burning more calories through physical activity – or a combination of the two. By eating fewer calories, your body uses its fat reserves for energy. As a result, fat is the main source of fuel that is burned and weight loss occurs. But it's not always that easy to lose weight. According to a 2018 article published inObesityWhen calories are restricted too much, your metabolism slows and hormones shift to conserve energy and prevent excessive weight loss. So a calorie deficitjust one factor in weight management.

Weight gain

When your calorie intake is consistently higher than the number of calories you burn, you enter a calorie surplus and experience weight gain. If your goal is to gain weight, not only is it necessary to consume more calories, but you should also consider strength training to increase your body mass in muscle. To reach your daily calorie goal, it may help to eat five to six meals throughout the day. It is also crucial to set prioritieshigh-calorie foods that are also high in nutrientsto ensure your weight gain is healthy.

How to count calories

By tracking the calories you consume, you can determine whether you are meeting or exceeding your recommended calorie intake. The first step in counting calories is determining how many calories you need each day. Both allow you to estimate your calorie needsDRI-calculatoror the Mifflin St-Jeor or Harris-Benedict formulas. Once your daily calorie needs have been calculated, you can start tracking the calories in each meal by recording the calories on the Nutrition Facts label or by looking up the calories for a specific food usingUSDA-database. Although many people use calorie tracking apps to track their energy intake, calorie counting can also be done with a detailed food diary or with the help of a registered dietitian. While calorie counting can be a useful strategy, it is important to note that it may not be helpful for people who are at risk for eating disorders or have a history of eating disorders. Therefore, it is more beneficial to focus on food quality and your overall diet, rather than focusing solely on calorie tracking.

Frequently Asked Questions

1. What does a calorie deficit mean?

A calorie deficit occurs when you take in fewer calories than you burn. This can be achieved by reducing your calorie intake or burning more calories through physical activity – or a combination of both.

2. What does a calorie surplus mean?

When your calorie intake is consistently higher than the number of calories you burn, you enter a calorie surplus and experience weight gain.

3. How Many Calories Should Adults Eat Every Day?

OfDiet guidancerecommends that adults ages 19 to 59 consume 1,600 to 3,000 calories daily. More specifically, adult women need about 1,600 to 2,400 calories per day, while adult men need about 2,000 to 3,000 calories per day.

4. What are empty calories?

According toAHAfoods that contain empty calories contain very few nutrients and a high number of calories.

5. How many calories should you eat per day to lose weight?

Losing weight requires a calorie deficit. A general rule of thumb is to reduce your calorie intake by 500 calories daily. But it's not always that easy to lose weight. Restricting calories too much can slow your metabolism as your body conserves energy and prevents excessive weight loss. Therefore, a calorie deficit is just one of the things you need to consider if you want to lose weight.

In short

The energy released during the breakdown of food is measured using a unit commonly called a calorie. Calories play a crucial role in fueling the many metabolic reactions in the body that keep you alive. Therefore, it is important to meet daily calorie needs and consume nutritious foods to ensure your body is nourished and functioning optimally. Your unique calorie needs depend largely on age, weight, body composition, physical activity level, gender, medical condition and hormone status. You may find it helpful to track your energy intake by counting calories. But assessment of food quality and overall dietary patterns is equally beneficial for managing nutritional intake.