If you’re looking into shedding the extra pounds you’ve probably wondered one or two times, “What is a calorie?” If you have been curious about the contents of what you buy, you might be familiar with the calorie contents found on the label of your favorite foods.
Food and weight management require looking into calories. But in reality, the definitions go beyond what the scales and nutrition facts say. In this article, we describe what a calorie really is, how this affects your weight and health, and how many you need in a day.
What You Need To Know:
- A calorie is a unit of heat or energy. Technically, it’s the amount of heat required to raise the temperature of 1 ml of water by 1 degree Celsius. In nutrition, it’s the amount of energy found in food and energy required by your body to fulfill its daily functions. (1 Calorie = 1 kilocalorie = 1000 small calories)
- Calories act as a fuel source of the body in order to perform its daily activities. It needs to maintain an energy balance of equal calories in vs calories out. An excess or deficit in calories results to an energy imbalance. This will have an effect on your weight and health as well.
- You get your source of calories from the food you eat. Consequently, you use up all this energy through your basal metabolism, physical activity, and the thermic effect of food.
- In general, women need about 2000 calories while men require around 2500 calories in a day to achieve energy balance. The number of calories you need would still be dependent on your age, weight, height, and physical activity levels. People who want to lose or gain weight would need different caloric requirements.
- You can achieve energy balance by keeping your portions in check, choosing nutrient-dense foods over empty calories, being mindful of what you eat, and staying active.
What Is A Calorie?
In technical terms, a calorie is the quantity of heat or energy required to increase the temperature of 1 ml of water by 1 degree Celsius. 1920s physicist and engineer coined the term calorie to describe the energy used in their fields.
Over time, it has become associated mostly with nutrition. It’s described as the potential energy in food to main bodily functions, grow or repair tissues, and perform mechanical work such as exercise.
In nutrition, the calories in food are actually kilocalories. Think of it as the larger unit of calories which is equivalent to 1000 small calories. However, to avoid further confusion, kilocalories are now more commonly known as just Calories (take note of the capital C), denoting the same amount of energy.
1 Calorie = 1 kilocalorie = 1000 small calories
What About Joules and Kilojoules?
Similarly, joules are also an international system unit for energy. One joule is equal to the energy transferred to an object when a force of one newton acts on it. Europe, Australia, and South Africa still use the term “kilojoule” to describe the amount of energy found in food. Since they also translate to a unit of energy, joules and calories only vary in their quantity.
1 kilocalorie = 4181.4 joules = 4.182 kilojoules
Calories and Your Health
Calories are essential for health as they power your body to perform their everyday functions. Food is the primary source of energy. Digestion takes place the moment we put food into our mouths, wherein the acids and enzymes in the body break down the nutrients into energy.
Calories and Energy Balance
The relationship between the amount of energy you put in (calories in) vs the amount of energy you burn (calories out) is called the energy balance. Ideally, people should eat just the right amount of calories to cover their energy expenditures.
However, more often than not, we have greater tendencies to consume more than expected. On the other hand, there also days where we might be too active or get too busy to eat. In these instances, our bodies go through an “energy imbalance”.
- Positive Energy Balance – If you eat more calories than you burn in a day, the excess energy will be stored and conserved in your body in the form of fat. This acts as a reserve in the event you encounter a negative energy balance.
- Negative Energy Balance – When you don’t eat enough or become quite active, your body becomes deficient in energy. To fulfill its energy needs, you start breaking down your energy reserves from fat and then your muscles.
Energy balance also largely impacts your weight. A positive energy balance makes you gain weight, while a negative energy balance makes you lose weight. To achieve your desired weight, it’s important to consider how much calories you put in and burn out.
Energy In: Calories From Food
Food and beverages provide the “energy in” in the energy balance equation. How much energy your body receives would be dependent on the type and composition of foods in your diet.
The number of calories in food can tell us their potential amount of energy. Macronutrients such as carbohydrate, proteins, and fats, all have different caloric values:
- A gram of carbohydrate = 4 kilocalories
- 1 gram of protein = 4 kilocalories
- A gram of fat = 9 kilocalories
These values mean that it’s not really all about the calories. If you’re looking to achieve caloric and energy balance, it’s best to have your macronutrients in check as well. To get an estimate of how much calories you need to eat in a day, use calorie calculating apps like MyFitnessPal.
Energy Out: Calorie Expenditures of the Body
The food you eat acts as fuel for your body. It does this by generating heat from the carbohydrates, fats, and proteins in your diet. The generation of heat is called thermogenesis, which also determines the amount of energy your body burns in a day.
Basal metabolism, physical activity, and thermal effect of food make up the total energy expenditure.
- Basal Metabolic Rate (BMR) – The basal metabolic rate is the rate at which the body expends energy to maintain daily bodily functions. To sustain basal metabolism, a person burns about two-thirds of their daily energy. These metabolic activities include maintaining your body temperature, respiratory functions, and organ activities.
- Physical Activity – The amount of voluntary movement you do with your skeletal muscles accounts as your physical activity. This component of energy expenditure is completely dependent on how much you move in a day including the amount of exercise and activity levels.
- Thermic Effect of Food – The way your body digests food also produces heat and burns up calories. The thermic effect of food is proportional to the food energy taken in and is usually estimated at around 10% of total energy intake. So if you ate 2000 kilocalories in a day, 200 kilocalories would be used on the thermic effect of food.
Here’s a way for you to find out your total daily energy expenditure. Just put in your age, weight, height, and activity levels, and this calculator will give you a rough amount of how much energy you burn in a day.
How Many Calories Do You Need In A Day?
On average, a woman typically needs around 1600 to 2400 Calories while men need about 2000 to 3000 Calories in a day to maintain weight. The number may vary depending on other factors like age, height, weight, activity levels, and metabolic health.
In practice, the USDA publishes a dietary guideline with the Estimated Caloric Needs per day based on age, sex, and physical activity levels.
Click here to find out your daily energy needs!
5 Tips to Achieve Energy Balance
- Check your proportions! Choose MyPlate is the current plate portion guide by the USDA. Allot half of your plate for fruits and vegetables, about a forth to proteins, and the rest for carbohydrates.
- Avoid Empty Calories. Munching on chips, sweets, and fast food won’t do your energy balance any good. These empty calorie foods only bulk you up with calories without giving the necessary nutrients to your body.
- Choose Nutrient-Dense Foods. Fruits, vegetables, lean proteins, eggs, nuts, legumes, and whole grains are nutrient-dense foods as they contain a lot of nutrients while being low in calories.
- Keep track of what you eat. With many of us distracted by our busy lifestyles, mindless eating can become a bad habit. Be aware of how much you eat by jotting it down in a notebook or logging it in through a calorie calculating app.
- Stay active! If you have a sedentary lifestyle, it’s important to include exercise in your weekly routines. Stay active by going on a run, hitting the gym, or joining fitness classes. Keeping your physical activity levels high with exercise will help in maintaining your weight and energy balance.
The Bottomline…
Technically speaking, a calorie is a unit of heat or energy needed to raise the temperature of 1 ml of water by 1 degree Celsius. But in nutrition, it basically dictates the amount of energy found in food and those needed by the body to carry out everyday functions.
You get your calories from the food you consume. This is then used up by the body to fuel your basal metabolism, physical activities, and thermic effect of food (energy needed to digest food). Energy balance happens when there’s an equal amount of calories in vs calories out. Any excesses and deficits in calories may lead to energy imbalances, which can have an impact on your weight and health.
Women generally require about 2000 calories, while men need around 2500 calories to sustain daily activities. This number may also vary depending on your age, weight, height, and physical activity levels. If you are looking to lose or gain weight, you will need a different caloric requirement.
You can attain energy balance through various techniques. Make sure you have your plate proportions under control, choose nutrient-dense foods, and avoid those that are considered empty calories, now that you know what is a calorie. Keep track of what you eat and stay active.
