The NHS says an average man needs about 2,500 calories a day and an average woman about 2,000. Your own needs depend on your size, age, sex and how active you are, and can easily be 500 or more calories higher or lower than these averages. You can estimate them with a simple formula, shown below, but treat the result as a starting point rather than an exact number. Your weight over a few weeks is the best guide to whether you’re eating about the right amount.
What calories are
A calorie (strictly a kilocalorie, or kcal) is a unit of energy. Your body uses energy for three main things:
- Basic body functions, such as breathing, circulation and keeping warm. This resting energy use is the biggest part for most people.
- Physical activity, from walking and housework to exercise. This varies the most between people.
- Digesting food, a smaller amount.
The NHS explains that if you eat and drink the same number of calories as you use, your weight stays about the same; more and you’re likely to gain, fewer and you’re likely to lose.
Estimate your needs in two steps
Step 1: Resting energy use
The Mifflin-St Jeor equation, published in the American Journal of Clinical Nutrition, estimates how many calories you use at rest:
- Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
Step 2: Add your activity
Multiply your resting figure by a rough activity factor. These are commonly used estimates:
| Activity level | Multiply by |
|---|---|
| Mostly sitting, little exercise | about 1.2 |
| Light exercise 1 to 3 days a week | about 1.375 |
| Moderate exercise 3 to 5 days a week | about 1.55 |
| Hard exercise most days | about 1.725 |
Worked examples
| Person | Resting estimate | Mostly sitting | Moderately active |
|---|---|---|---|
| Woman, 35, 165 cm, 65 kg | about 1,345 kcal | about 1,610 kcal | about 2,085 kcal |
| Man, 40, 178 cm, 80 kg | about 1,720 kcal | about 2,060 kcal | about 2,660 kcal |
These are estimates. Two people of the same size can differ by a few hundred calories a day.
How calorie needs change
- Age: needs usually fall slowly with age, partly because muscle mass declines.
- Size and muscle: bigger and more muscular bodies use more energy.
- Activity: the biggest factor you can change. More walking and less sitting make a real difference over time.
- Teenagers: growing teens need more. The American Academy of Pediatrics gives about 2,800 calories a day for teenage boys and 2,200 for girls.
- Pregnancy and breastfeeding: needs change at different stages, so follow your midwife’s advice. Pregnancy isn’t a time to diet.
Calories for weight loss
To lose weight, you need to use more energy than you take in, through eating a little less, moving a little more, or both. A slow, steady approach is easier to keep up and helps protect muscle. Very low-calorie diets can work for some people, but the NHS warns that a very strict, low-calorie diet may not be suitable if you take insulin or other diabetes medicines, and these diets should be supervised.
Rather than counting every calorie forever, many people find it easier to change habits: smaller portions of starchy and fatty foods, more vegetables, fewer sugary drinks, and more protein and fiber to stay full. Our guide to building a balanced meal shows how.
Not all calories act the same
The type of food matters as well as the amount. In a tightly controlled US trial, 20 adults ate about 508 more calories a day when offered ultra-processed food than when offered minimally processed food, with meals matched for calories, sugar, fat and fiber, and they gained weight on the ultra-processed diet. Foods high in protein and fiber, such as vegetables, beans, whole grains, fish, eggs and yogurt, tend to be more filling for their calories than sugary drinks, pastries and fried snacks. Our guide to whole foods explains more.
Reading calories on labels
- Check the serving size: a packet may contain two or more servings.
- Look at drinks: juices, smoothies, coffees and alcohol can add hundreds of calories. Our guide to calories in alcohol has examples.
- Kilojoules (kJ): some labels show energy in kJ. 1 kcal is about 4.2 kJ.
A note on counting calories
Calorie tracking helps some people understand their eating, but it can become stressful or obsessive for others. If counting makes you anxious, or you find yourself restricting food heavily, stop and talk to your doctor. An eating disorder is serious but treatable, and if you need someone to talk to now, findahelpline.com lists free helplines in many countries. Our guide to mindful eating offers a gentler approach.
Common questions
Is 1,200 calories a day enough?
For most adults, 1,200 calories a day is well below their needs and hard to meet nutrient needs on, so it’s not something to try for long without professional advice. Your own needs may be much higher.
Do I need to eat back the calories I burn exercising?
Not necessarily. Activity trackers can overestimate calories burned. Use your weight and energy levels over a few weeks as a guide.
Why am I not losing weight on fewer calories?
It’s easy to underestimate what you eat, especially snacks, drinks and oils. Weight also fluctuates day to day with water. Look at the trend over 2 to 4 weeks, and if you’re concerned, talk to your doctor or a dietitian.
Do men and women need different amounts?
On average, yes, mostly because of differences in body size and muscle. That’s why the NHS gives 2,500 kcal for an average man and 2,000 kcal for an average woman. A tall, active woman may need more than a small, inactive man.
Should I count calories to eat healthily?
Not necessarily. Many people eat well by focusing on food quality, portions and regular meals. Counting can be a useful short-term tool for some people.
This article is general information, not medical advice. Talk to your doctor or a registered dietitian before making big changes to how you eat, especially if you have a health condition, take regular medication, or are pregnant or breastfeeding.
