STEP 1: ENERGY BALANCE
To calculate your Basal Metabolic Rate (BMR):
- For men: BMR = (10 x weight kg) + (6.25 x height cm) – (5 x age years) + 5
- For women: BMR = (10 x weight kg) + (6.25 x height cm) – (5 x age years) – 161
e.g. 29 year old female weighing 60kg and 160cm in height
(10 x 60) + (6.25 x 160) – (5 x 29) – 161
600 + 1000 – 145 – 161 = 1294 calories
STEP 2: ADJUST FOR ACTIVITY LEVELS
You need to add an ‘activity multiplier’ (x1.2~x1.9) to your BMR depending on your lifestyle/training.
- Sedentary(little or no exercise): BMR x 1.2
- Lightly active(training/sports 2-3 days/week): BMR x 1.375
- Moderately active(training/sports 4-5 days/week): BMR x 1.55
- Very active(training/sports 6-7 days a week): BMR x 1.725
- Extremely active(training/sports and physical job): BMR x 1.9
e.g. training 4-5 days per week
1294 x 1.55 = 2005 calories
This is your total daily energy expenditure (TDEE) i.e. the total number of calories maintaining your current weight.
STEP 3: SET FAT LOSS OR MUSCLE GAIN TARGETS
Decide whether you want to gain muscle or lose fat as priority.
To work out fat loss calories you minus 500 calories per day to lose ~0.45kg fat per week, which is a sustainable and realistic amount to lose.
e.g. 2005 – 500 = 1505 calories
For muscle gain an approximate 1:1 ratio of muscle to fat gain is realistic for most people.
To gain 1kg of muscle per month, you’ll need to gain 2kg of body weight, and will require a 440 kcal daily calorie surplus. Therefore if you want to add 0.45kg of muscle in a month you’ll need this equation:
TDEE + (0.45 x 440)
e.g. 2005 + (0.45 x 440) = 2203
STEP 4: SETTING MACROS FOR FAT LOSS
- Protein has 4 calories per gram.
- Carbohydrates have 4 calories per gram.
- Fat has 9 calories per gram.
Protein: as a general rule you need 2.2g of protein per kg of body weight.
e.g. 2.2g x 60kg = 132g of protein
in calories this is 132 x 4 = 528
Fat: as a general rule you need 0.85g of fat per kg of body weight.
e.g. 0.85 x 60kg = 51g fat
in calories this is 51 x 9 = 459
Carbohydrates: whatever is left in the calorie allowance after protein and fat have been calculated is the carbohydrate amount.
e.g. 1505 calories – (528 – 459) = 518 calories
in grams this is 518 / 4 = 129.5g
Alternatively if you use My Fitness Pal to track your food, then setting the percentage split to 35% protein, 35% carbohydrates and 30% fat will get a similar result which is good enough for the majority of us.