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Calories versus fats

A common problem for anyone trying to lose weight is eating too much and not being active enough.

Weight gain happens when the energy you get from food (calories), is more than the energy you use being active. The more you move the more calories you use.

What are calories?

Energy is another word for calories. Calories are the measure for 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.

The more we eat and drink the more calories we take in. To put it simply:

More energy IN than OUT over time = weight gain

More energy OUT than IN over time = weight loss

As a guide, an average man needs about 2,500kcal a day and a woman about 2,000kcal a day to maintain a healthy body weight. But these values can vary depending on a person's age, size and levels of physical activity.

When trying to lose weight, the general rule is to reduce your calorie intake to 500 fewer calories than your body needs to maintain your current weight. This will help you lose about 1 pound (0.5 kg) of body weight per week. Learn more about calorie and energy balances.

Why do I need calories?

Our bodies need energy to keep us alive. We use the energy we gain from eating foods to allow our organs and body to move and function.

To maintain a healthy weight, the energy (calories) we eat needs to be roughly the same as the energy we use (through being active and exercise).

To lose weight, we need to lower the number of calories we eat or significantly increase our activity. The more we move when doing activity, the more energy (calories) we use.

Are calories and fats different?

It's important to use your calorie or energy intake wisely and choose healthy foods that benefit your body and health.

Knowing the calorie content of food and drink can ensure you're not consuming too much energy. You'll find this information listed on the food labels on prepared foods and drinks. Find out more about food labels.

These labels help you make choices about what to eat and drink to lose weight or maintain your current weight. As well as energy, also listed on the labels are the amount of fats, sugars and salt that the food contains. Find out more about fats, plus sugars and salt, at What is healthy eating: the Eatwell Guide.