Calories are the measurement of the amount of energy in an item of food or drink.
When we eat and drink more calories than we use up, our bodies store the excess as body fat. If this continues, over time we may put on weight.
As a guide, an average man needs around 2,500kcal (10,500kJ) a day to maintain a healthy body weight and for an average woman, that figure is around 2,000kcal (8,400kJ) a day. These values can vary depending on age, size and levels of physical activity, among other factors.
Check if you’re a healthy weight by using our body mass index (BMI) calculator