Knowing how many kilojoules you need is essential to weight loss. Photo: Thinkstock

### Just how much energy do we use?

The following figures are how much energy a person uses, in kilojoules per kilogram of body weight per hour (kJ/kg/h), during various activities. Scroll down to calulate how many kilojoules you need each day.

 Writing: 1.7 kJ/kg/h Sitting quietly: 1.7 Walking rapidly: 14.2 Standing relaxed: 2.1 Running: 29.3 Driving a car: 3.8 Swimming (4km/h): 33 Vacuuming: 11.3 Rowing in a race: 67

### 1. Calculate your metabolic rate

Basal metabolic rate (BMR) is how many megajoules (MJ, or 1000kJ) you burn, at rest, per day

 18-30 years old 31-60 years old Men 0.063 x body weight (kg) + 2.896 = BMR in MJ 0.048 x body weight (kg) + 3.653 = BMR in MJ Women 0.062 x body weight (kg) + 2.036 = BMR in MJ 0.034 x body weight (kg) + 3.538 = BMR in MJ

### 2. Gauge your average daily activity level

Multiply your BMR by the figure below from the category that best reflects your daily activity level

 Men Women Sedentary 1.4 1.4 Light 1.5 1.5 Moderate 1.8 1.7 Heavy 2.1 1.8

### 3. The result is your energy need

Multiply your answer by 1000 to determine how many kilojoules you need just to get through the day. Eat more, you’ll gain weight. Eat less and you’ll lose it.

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