Calories and Kilocalories

You need calories for energy and controlling your weight; understanding terms such as kilocalories and calories can keep you from getting confused when planning your diet. In nutrition, the terms are usually interchangeable, and the numbers that you see on food packages or in the gym are referring to the same thing. A nutritionist can help you determine the right number of calories or kilocalories for your situation, and count your foods correctly.

Definitions

A calorie is a scientific unit of heat, and the technical definition of a calorie is the amount of heat that it requires to raise 1 g of water by 1 degree Celsius. A kilocalorie, or calorie, refers to 1,000 calories. You usually see the number of calories in a food stated in terms of calories, and this really refers to kilocalories. For example, a label stating that the food has 100 calories per serving really means that the food has 100 kilocalories per serving. A standard 2,000-calorie diet really means a 2,000-kilocalorie diet.

Calorie Intake

Your body uses calories to get fuel through energy-generating reactions using calories from carbohydrates, proteins and fats in your food. Carbohydrates and proteins supply about 4 calories per gram, and fats provide 9 calories per gram. Alcohol is not essential to your diet, but it has 7 calories per gram, according to the Mayo Clinic. Water, vitamins and minerals are essential nutrients, but they do not supply calories. The amount of calories, or kilocalories, that you get from food is your calorie consumption or intake.

Calorie Expenditure

Calories allow your body to produce energy for metabolic processes to keep you alive, such as breathing and blood circulation. The amount of calories you need per day for these functions is called your basal metabolic rate, and it takes about 60 to 75 percent of the calories that you eat. Your body needs about 10 percent of the calories you eat for thermogenesis, which includes digesting and transporting nutrients from your food. The remainder of the calories you need is for physical activity.

Weight Control

You are in calorie balance when you eat the same number of calories that you burn and your weight is stable. If you eat more calories than you burn through basal metabolism, thermogenesis and physical activity, you will store the excess as fat and gain weight. To lose weight, you need to create a calorie deficit. This means that you eat fewer calories than you burn through a combination of eating less, exercising or both.