Losing weight is very simple. You just need to burn more energy (calories) than you consume. But how do you work out how many calories you burn each day. And how do you use that information to plan a successful weight loss diet?

Step 1 – Calculate your Resting Metabolic Rate (RMR)

Your RMR is the number of calories your body burns on essential body functions, such as breathing and blood circulation while you sleep. It is the basis for all the other calculations, and varies according to your age, sex and weight. It is very important to get this figure right, as a wrong number here will ruin the rest of your calculations.

Age	Male	Female
10-18 Years	(body weight in kg x 17.5) + 651	(body weight in kg x 12.2) + 746
18-30 Years	(body weight in kg x 15.3) + 679	(body weight in kg x 14.7) + 496
31-60 Years	(body weight in kg x 11.6) + 879	(body weight in kg x 8.7) + 829

I’ll calculate my RMR as an example:

I’m a 26 year old male, and my weight in kg is 131.5kg, so my RMR is:

(131.5 x 15.3) + 679 = 2691 kcal

Step 2 – Calculate your daily energy expenditure

This stage uses your RMR and your daily activity level to calculate how much energy your body burns over the course of an average day. The more active you are, the more energy your body will burn. Calculate as follows:

• If you are mostly sedentary (mostly seated or standing activities during the day): RMR x 1.4

• If you are moderately active (regular brisk walking or equivalent during the day): RMR x 1.7

• If you are very active (generally physically active during the day): RMR x 2.0

So continuing with me as an example:

I am mostly sedentary during the day, so I need to multiply my RMR by 1.4:

2691 x 1.4 = 3767 kcal

Step 3 – Calculate the number of calories you use during exercise

Work out how many calories you burn during exercise over the course of the week, and divide by 7.

Example: I walk on average for 45 minutes per day 5 days per week. Each walk burns 240 calories. So my exercise calories for the week are:

Exercise calories per week: 240 x 5 = 1200

Then divide this number by 7 to get your daily average:

Exercise calories per day : 1200/7 = 171 calories per day

Step 4 – Add together the figures from steps 2 and 3

This figure is the amount of energy your body needs each day to maintain your current weight. If you consume more calories than this, you will gain weight, if you consume fewer calories, you will lose weight. If you currently consume considerably more or less than this figure, you should take a few weeks to gradually move your intake to this figure before attempting the following steps.

Example:

My maintenance calorie intake: 3767 + 171 = 3938 kcal

My current average daily calorie intake is 2300kcal per day. I am gradually increasing my intake over the next few weeks until it reaches around 3900. I’ll add 400 calories per week for the next 4 weeks. This will not result in me gaining any weight, as I am keeping below my maintenance calorie intake, but it will slow my weight loss and hopefully prevent me from losing any more muscle.

Step 5 – Reduce your calorie intake by 15%

Once you are consistently eating your maintenance calorie intake each day, the next step is to reduce your calorie intake to begin a controlled long term weight loss. To do this, you should reduce your calorie intake by no more than 15%. Reduce it by any more than this and you will start to lose muscle, which will make it harder to lose weight in the long run, and probably result in you not being able to maintain your weight loss (I’ll cover this in more detail in an upcoming article).

Example:

My weight loss calorie intake would be: 3938 x 85% = 3347 kcal per day

Step 6 – Calculate your carbohydrate needs

So now you know how many calories you should be eating each day to lose weight. Now it’s time to calculate how you should be consuming those calories, starting with carbohydrates.

During a fat loss program, you should be aiming to get around 60% of your daily calories from carbohydrates. So first calculate 60% of your weight loss calorie intake. Then take this figure and divide by 4, to give you your carbohydrate intake in g (each g of carbohydrate provides 4kcal of energy)

Example:

My weight loss calorie intake is 3347. So my calorie intake from carbohydrate should be 3347 x 60% = 2008kcal.

2008/4 = 502g of carbohydrate per day

Step 7 – Calculate your protein needs

During a fat loss program, your body needs approximately 1.6g of protein per kg of body weight to prevent muscle loss. Again, remember to reduce this by 15%, as your total calorie intake has reduced by this amount.

Example:

My weight in kg is 131.5kg, so my protein requirement is (131.5 x 1.6) x 85% = 179g

Step 8 – Calculate your fat needs

The remainder of your calories after your carbohydrate and protein requirements have been met should come from fat. Remember, your body needs fat to function properly, so don’t try and cut your fat intake too low, no matter what you may have heard!

To calculate the number of calories you have remaining for fat, you first need to work out how many you have already used. You already know the calories used on carbohydrates from your calculations above. Protein also provides 4kcal of energy per g, so to find out the amount of calories your protein provides, simply multiply by 4. You can then subtract your carbohydrate and protein intake from your calorie total, which gives you your calorie total for fat. Fat provides 9kcal of energy per g, so to calculate how much fat you need, divide the calorie amount by 9.

Example:

Carbohydrate will provide me with 2008kcal. Protein will provide me with 716kcal (179 x 4).

So my remaining calories for fat are: 3347 – (2008 + 716) = 623kcal

Therefore my daily fat intake in g = 623/9 = 69g

This leaves my final nutritional intake as:

Energy = 3347kcal

Carbohydrate = 502g (60% of total)

Protein = 179g (21% of total)

Fat = 69g (19% of total)

This intake should provide me with a fat loss of approximately of 0.5kg (1lb) per week, whilst maintaining my muscle mass. It may seem like a very slow weight loss, but as I won’t lose any muscle mass, and I’m not depriving myself with a very low calorie intake, it is one I can maintain long term. It will also leave me with a very good fitness and muscle base for when I start my training for LEJOG in around 18 months time.

Also bare in mind that there are ways to speed up the fat loss without losing muscle, which I’ll look at in a future article, but none of them will be successful long term until you do the basics right.

I would really appreciate your comments on this article, as I am still in the very early stages of my weight loss, and I always welcome new ideas. You can contact me using the comments button below, or through Facebook, Twitter or any of the other places mentioned in the ‘Find Me Online’ box on the left of this page.

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Until next time

Kevin