Weight Loss Calculator Shows You How to Lose Weight by Eating Less and Exercising More

Use our Weight Loss Calculator Daily Activity Chart to Work out your Daily Calorie Needs for How to Lose Weight

1. Basal or resting metabolic rate

This is the amount of calories our body needs to pump oxygen around the body at rest, i.e purely to survive. This 'state' never really exists so it would be a zero on the activity chart below.

RMR accounts for around 60% of a person’s energy requirement.

My weight loss calculator uses a method of determining a person’s RMR based on calories burned by your lean tissue or lean body mass (LBM) in Kg.

Multiply LBM by 21.6 and add 370.


LBM 75kg x 21.6 + 370 = 1990 calories (RMR requirement)

2. Daily calorie requirements to maintain weight

Once we know the RMR requirement, we need to calculate the amount of physical activity that an individual engages in on a daily basis.

The following table will assist you in determining the daily energy expenditure.

Once you have determined your physical activity level (PAL), you will be able to calculate your daily calorie requirement.

If we use the example on the prior page (say for a man), we can add in the PAL factor. So if we calculate the activity level to be 1.3 it would add up as follows:


LBM 75kg x 21.6 + 370 = 1,990 calories (RMR requirement)

x PAL factor 1.3 = 2,587

3. Energy expended during exercise

If someone exercised only on the odd day use the moderate factor but add the following calculation for energy expended during exercise:

4.3 calories x by body weight in Lb’s per hour.

Aerobic exercise example:

166lbs total body weight x 4.3 calories per hour = 713

4. Use the Weight Loss Calculator to Create Your Personal Calorie Deficit

The only safe and effective way to lose weight is to create a daily calorie deficit.

It is recommended that you reduce the daily calorie requirement by no more than 20%. If a calorie reduction is greater than this, the metabolism will slow down and LBM will be reduced rather than fat.


LBM 75kg x 21.6 + 370 = 1,990 calories (RMR requirement)

x PAL factor 1.3 = 2,587

x 20% minus (517.4) = 2,069.6 calories

So how to lose weight?

Using this weight loss calculation, if the individual in this example reduced his or her weight by 500 calories per day they would burn 3,500 calories per week, which is equal to 1lb of stored body fat.

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