Question

I need to calculate if I'm going to gain or lose weight in next 6 moths,based on energy intake and consumption. Which formulas do I need to use?

Answer 1

STEP 1: CALCULATE YOUR BASAL METABOLIC RATE (BMR)

This formula is the revised Harris-Benedict equation. It can get a bit confusing, so stay with me!

The formula is: 447.593 + (9.247 x body weight (kg)) + (3.098 x height (cm)) – (4.33 x age in years)

My weight is around 52kgs, my height is 167cm and my age is 27 years. So here’s my example.

447.593 + (9.247 x 52) + (3.098 x 167) – (4.33 x 27)

= 1329 calories

This means that if I were to lie in bed all day and do absolutely nothing, my body would use up 1329 calories per day.

STEP 2. CALCULATE YOUR TOTAL ENERGY EXPENDITURE (TEE)

Multiply your BMR by the TEE value below, based on your activity level.

Little to none     1.2

Light (1-3 days) 1.375

Moderate (3-5 days)      1.55

Heavy (6-7 days)              1.725

Very heavy (twice daily)               1.9

I exercise 6 times per week for about an hour, but usually 2 of these sessions are low intensity cardio such as power walking. I would considerate myself in the moderate range so I will multiply my BMR (1329) by 1.55.

Total Energy Expenditure = 1329 x 1.55 = 2060 calories.

This means that if I were to exercise 5 times per week, my body would burn 2060 calories per day.

STEP 3: CALCULATE YOUR IDEAL CALORIE INTAKE

Fat Loss

Usually for fat loss, you should be in a calorie deficit of around 200-500 calories. A more severe calorie restriction will result in a more severe fat loss. However, any form of dieting and calorie restriction will reduce your metabolic rate, so just keep that in mind (also remember that resistance training increases your metabolic rate).

I like to be at a 300 calorie deficit because I don’t get as hungry. Therefore, my ideal calorie intake should be 2060 – 300 = 1760 calories.

But if I were to be at the 500 calorie deficit, my ideal calorie intake would be 2060 – 500 = 1560 calories.

Maintenance

If you are trying to maintain your weight, you would just stick to your total energy expenditure, which would be 2060 calories for me (which we worked out in step 2).

Weight Gain

If you are trying to gain weight, you would want to eat more than 2060 calories.