A calorie is a unit of energy. Historically, scientists have defined "calorie" to mean a unit of energy or heat that could come from a variety of sources, such as coal or gas. In a nutritional sense, all types of food — whether they are fats, proteins, carbohydrates or sugars — are important sources of calories, which people need to live and function. In , calories became scientifically defined in terms of joules, which are units typically used by physicists to describe the amount of work needed to force one newton through one meter.
This is why you sometimes see calories being called kilojoules, especially in Europe and Australia. One calorie equals 4. The amount of heat needed to make a calorie differs at different temperatures, so scientists decided to create different types of calories according to their water temperature. Different temperatures yield different types of calories, such as the small calorie, also called the gram calorie or the degree calorie.
This calorie refers to the amount of heat needed to raise the temperature of 1 gram of water from A calorie in nutrition is actually 1, of these small calories. Some researchers use the term kilocalories to refer to the nutritional unit of 1, small calories. These units of 1, small calories are also sometimes called large calories, dietary calories, nutritional calories, food calories and Calories with a capital C. Therefore, what Americans see on food labels are actually kilocalories, or kilojoules.
When the U. Department of Agriculture says that one medium-size apple contains 95 calories, it actually contains 95 kilocalories. This article uses the term calorie instead of kilocalories. Different types of macronutrients have standard amounts of calories.
One gram of protein has 4 calories. One gram of carbohydrates has 4 calories. One gram of fat has 9 calories, according to the McKinley Health Center. The National Institutes of Health NIH provides general guidelines of calorie requirements for various ages and activity levels. A middle-age moderately active female should consume 2, calories per day.
A middle-age moderately active male should consume 2, to 2, calories per day. The official Dietary Reference Intakes DRI published by the National Academies of Sciences, Engineering and Medicine recommends that for an adult, 45 to 65 percent of calories should come from carbohydrates , 20 to 25 percent should come from fat and 10 to 35 percent should come from protein.
Children need a higher proportion of fat, between 25 and 40 percent of their calories. No more than 25 percent of total calories should come from added sugars. Exercising and playing are really important, too, because physical activity burns calories.
Your body needs calories just to operate — to keep your heart beating and your lungs breathing. As a kid, your body also needs calories and nutrients from a variety of foods to grow and develop. And you burn off some calories without even thinking about it — by walking your dog or making your bed. But it is a great idea to play and be active for an 1 hour or more every day. That means time spent playing sports, playing outside, or riding your bike. It all adds up. Being active every day keeps your body strong and can help you maintain a healthy weight.
Watching TV and playing video games won't burn many calories at all, which is why you should limit those activities to no more than 2 hours per day. A person burns only about 1 calorie per minute while watching TV, about the same as sleeping! Reviewed by: Mary L. Gavin, MD. If you have diabetes, your health care provider may suggest sticking to the lower end of the range.
Carbohydrates contain 4 calories per gram. If you typically consume around 2, calories per day, 45 to 65 percent of your calories is equivalent to to grams of carbs. An 1,calorie diet requires to grams of carbohydrates, while a 2, calorie diet allows you to have to grams. Carbohydrates can be simple or complex. Simple carbs include refined white sugar and high fructose corn syrup.
These types of carbohydrates add excessive calories to your diet, since foods high in sweeteners are usually low in nutrients. Simple carbs cause your blood glucose to suddenly spike and then drop shortly after you eat.
This may cause you to feel hungry again soon after eating a piece of cake, or other food high in sugar. Not all simple carbs are created equal. Fruit sugar, known as fructose, and milk sugar, called lactose, are also simple carbohydrates. These simple carbs are naturally occurring in foods and are healthier options, since foods containing these sugars provide beneficial fiber, protein and some healthy fats. A single serving of fruit contains 15 grams of primarily simple carbohydrates.
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