Calories are the amount of energy released when your body breaks down (digests and absorbs) food. The more calories a food has, the more energy it can provide to your body. When you eat more calories than you need, your body stores the extra calories as body fat. Even fat-free food can have a lot of calories. The human body needs calories to survive. Without energy, the cells in the body would die, the heart and lungs would stop, and the organs would not be able to carry out the basic processes needed for a living. People absorb this energy from food and drink.

The calorie content described on food labels refers to kilocalories (kcal). The average man needs a total fat intake of 25-35 percent calories. That's about 80 grams of fat or less a day if you eat 2,000 calories a day. People have different metabolisms that burn energy at different rates, and some people have more active lifestyles than others. The recommended intake of calories per day depends on several factors, including overall general health, age, physical activity demands, sex, weight, height, body shape and so on. Calorie consumption that is too low or too high will eventually lead to health problems.

Researchers at Tel Aviv University wrote in the journal "Obesity", that a large breakfast containing approximately 700 kcal is ideal for losing weight and lowering the risk of diabetes, heart disease, and high cholesterol. A high intake of calories can be countered with regular, high-intensity exercise.

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