What Is a Calorie?
A calorie is a unit of energy. It measures the amount of energy food provides to your body. In simple terms, calories are what fuel your body to perform every function—from breathing and thinking to running and exercising.
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1 calorie (small calorie) = the energy needed to raise 1 gram of water by 1°C.
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1 kilocalorie (kcal) = 1,000 small calories, and this is the calorie number listed on food packages.
How Calories Work
Your body needs calories to perform basic functions (basal metabolism) and physical activities:
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Basal Metabolic Rate (BMR): Energy used for essential functions like heart beating, brain activity, and digestion.
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Physical Activity: Running, walking, and even typing burns calories.
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Thermic Effect of Food: Energy used to digest, absorb, and process nutrients.
Sources of Calories
Calories come from three main macronutrients in food:
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Carbohydrates: 4 kcal per gram, found in rice, bread, and fruits.
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Proteins: 4 kcal per gram, found in meat, beans, and eggs.
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Fats: 9 kcal per gram, found in oils, nuts, and butter.
Alcohol also provides energy at 7 kcal per gram but isn’t considered a nutrient.
Why Calories Matter
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Weight Management: Eating more calories than you burn leads to weight gain, while eating fewer can result in weight loss.
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Energy Levels: Calories give you the energy to stay active and alert throughout the day.
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Health: Maintaining the right balance of calories supports overall health, prevents malnutrition, and reduces the risk of chronic diseases.
Fun Facts About Calories
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The word “calorie” comes from the Latin word “calor”, meaning heat.
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Even small daily activities, like brushing your teeth, burn a few calories.
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Not all calories are created equal: nutrient-dense calories (like from vegetables and whole grains) are healthier than empty calories (like from sugary snacks).