How many calories you need to lose weight

By Clare Collins PhD, AdvAPD, Associate Professor in Nutrition & Dietetics

Healthy breakfast, lunch and dinner

To lose weight, you need to reduce your total daily calorie intake from the level you consume now. If your weight is stable at the moment, meaning it stays the same week after week, then to lose 0.5–1kg a week you would need to reduce your calories by 500 to 1000 a day. That is 3500 to 7000 calories over a week. This is because one kilogram of body weight on the scales contains roughly 700g of actual fat. Each gram of fat is worth 10 calories.

What is a calorie?

Calories and kilojoules are measures of how much heat is released in your body when you burn up food. A lot of this heat is released when we burn up the food in our muscles during exercise, however, every move you make burns up energy – even if it’s in very small amounts.

How is my daily calorie target calculated?

The daily calorie target you have been assigned by The Club is based on your Basal Metabolic Rate (BMR) which is a guide to how much energy your body needs to function on a daily basis e.g. to breathe, digest food, stand up, etc. The Club calculates your BMR using the Harris-Benedict equations which take into account your height, weight, age and gender. We then multiply your BMR by an activity factor which represents your everyday activity level (e.g. sedentary, office worker, etc.) This provides an estimate of your total energy expenditure, from which we deduct roughly 500 calories to achieve the ‘negative energy balance’ required for weight-loss.

Negative energy balance means your ‘energy in’ is less than your ‘energy out’. Or in other words, you’re using more energy through everyday activity and exercise than you’re consuming through food and drink.

How to cut the calories

There are a number of different ways that you can cut calories from your usual daily food intake. They all work, but some are easier to do than others.

  • Go lite: Swap to low fat, lower calorie versions of your favourite foods and drinks. Low fat versions will contain less fat and diet versions will contain less sugar. By looking at food labels and comparing the total calories per 100g, you will be able to see what a big difference this makes to the total calories.
  • Bulk up the vegies: Reduce the calories in meals by increasing the amount of low calorie vegetables and salad items you include. For example 100g of meat provides about 200 calories while 100g of carrots has 40 calories and 100g of and celery has 14. Try adding canned tomatoes to casseroles – a whole 400g can has just 88 calories
  • Cut the portion size: Smaller portions means less calories. Use smaller plates and cups so you do not the smaller serve. Research shows than when we use big bowls and plates, we eat more. That means more calories consumed without you even realising.
  • Swap it: If there is a food or drink you like to have regularly, such as cola, then check the calories in food search and see if you can find a better alternative. For example, you could swap to a diet version or something completely different that is low in calories. Another example is swapping a high-calorie chocolate bar for diet chocolate mousse.

What else helps you cut calories?

Keeping a food diary will help you work out where your calories come from. Being really honest when recording your foods will help you learn about what you usually eat. Then, you can look for ways of cutting calories from your usual intake. Another good tip is to plan your meals and snacks ahead of time – this means you are be more likely to avoid situations where you will be tempted to overeat.