Calories are units of measurement for the quantity of energy in a meal or beverage. When we consume more calories than we burn, our bodies store the extra as body fat. If this continues, we may gain weight over time. Eating too few calories can also be harmful: without enough energy to function normally, people will become weak and vulnerable to illness. In addition to eating too much food and not enough exercise, your body mass index (BMI) is another factor that determines how many calories you need each day. There are different categories of BMI, with each category indicating a different level of risk - it's important to keep yourself within your recommended calorie range no matter what category you're in. Your body uses calories from both food and alcohol to function properly. The amount of energy you need daily depends on several factors such as your size, age and activity level. It is best to follow the advice of a dietician who can calculate the right number for you. Calories can be divided into two groups depending on whether they come from carbohydrates, proteins or fats. Each type of nutrient plays an important role in blood sugar regulation, muscle development and health in general. By knowing how each type of calorie affects your body, you can choose the most effective strategy for losing weight and keeping it off.