1. Energy (calories)
Where do I get energy?
You get energy from four components in food and drink: carbohydrate, fat, protein and alcohol. These fuels are broken down in your body and transformed via various biochemical pathways into a compound called adenosine triphosphate (ATP). Energy is produced when one of the phosphate molecules splits off, leaving adenosine diphosphate (ADP). This energy can then be used to fuel your muscles.
How many calories do I need?
You can estimate your daily calorie needs by working out your basal metabolic rate (BMR) and multiplying it by your physical activity level. Your BMR is the number of calories you burn at rest over 24 hours maintaining essential functions such as respiration, digestion and brain function. BMR accounts for 60–75 per cent of the calories you burn daily. Step 1: Estimate your basal metabolic rate (BMR):
(A) Quick method: As a rule of thumb, BMR uses 11 calories for every 0.5 kg
of a woman’s body weight and 12 calories per 0.5 kg of a man’s body weight.
Women: BMR weight in kilos 2 11 (alternatively weight in
Men: BMR weight in kilos 2 12 (alternatively weight in pounds 12)
Example: BMR for a 60 kg woman 60 2 11 1,320 kcal.
(B) Longer method: For a more accurate estimation of your BMR, use the
Step 2: Estimate your physical activity level (PAL): Your physical activity level (PAL) is the ratio of your overall daily energy expenditure to your BMR. It’s a rough measure of your lifestyle activity. Mostly inactive or sedentary (mainly sitting):
1.2 Fairly active (include walking and exercise 1–2 week): 1.3
Moderately active (exercise 2–3 weekly): 1.4
Active (exercise hard more than 3 weekly): 1.5
Very active (exercise hard daily): 1.7
Step 3: Multiply your BMR by your PAL to work out your daily calorie needs:
BMR x PAL
Example: daily energy needs for an active 60 kg woman 1,351 1.5 2,027 kcal. That’s how many calories you burn a day to maintain your weight, assuming
you have an ‘average’ body composition. If you have higher than average
muscle mass add 150 calories.
To lose weight, reduce your daily calorie intake by 15 per cent or multiply the
figure above (maintenance calorie needs) by 0.85. This will produce a fat loss
of about 0.5 kg per week.
Example: Daily energy needs for an active 60 kg woman to lose weight 2,027
0.85 1,723 kcal.
To gain weight, increase your daily calorie intake by 20 per cent or multiply the
figure above (maintenance calorie needs) by 1.2. In conjunction with a
resistance training programme, expect a weight gain of 0.25–0.5 kg per month.
Example: Daily energy needs for an active 60 kg woman to gain weight 2,027
1.2 2,432 kcal.