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Calories and Energy
Calories measure the energy food provides. Balancing the calories you eat with those you use helps keep a healthy weight — roughly 2,000 a day for women and 2,500 for men as a guide.
What it is
A calorie (kilocalorie, kcal) is a unit of energy. Foods provide energy from carbohydrate, fat, protein and alcohol, and the body uses this energy to function and move.
What it does
Energy from food powers everything the body does, from breathing and keeping warm to physical activity. Balancing energy in and energy out over time affects body weight.
Good sources
All foods and drinks except water provide calories. Fat is the most energy-dense (per gram), followed by alcohol, then carbohydrate and protein.
Deficiency and who is at risk
Consistently taking in far fewer calories than the body needs leads to weight loss and, if severe, malnutrition, tiredness and loss of muscle. Needs vary with age, size, sex and activity.
Balance
Can you have too much?
Regularly eating more calories than the body uses leads to weight gain over time. As a rough guide, adults need around 2,000 kcal a day for women and 2,500 kcal for men, though individual needs differ.
Education and reference only. This is general nutrition information, not personal advice, and does not give doses. Ask a pharmacist, GP or registered dietitian before starting supplements, especially with a health condition or in pregnancy.
Answers
Calories and Energy: frequently asked questions
How many calories should I eat a day?
As a general guide, around 2,000 kcal a day for women and 2,500 kcal for men, but your actual needs depend on your age, size, muscle and how active you are.
Are all calories the same?
A calorie is a unit of energy, but foods differ hugely in their nutrients and how filling they are. The same calories from vegetables and wholegrains support health far better than from sugary or highly processed foods.
Related
More on others and nutrition
Sources
Where this is drawn from
- NHS — Eat well
- British Dietetic Association (BDA)
- UK Scientific Advisory Committee on Nutrition (SACN)
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