Burning Off Kilojoules

You need to burn off around 15,000 kilojoules (3500 calories) more than you take in if you want to shed half a kilogram (1lb).

There are a couple of ways of achieving this. You can either drastically reduce your kilojoule intake so that your body starts to feed off its own reserves, or you can maintain your present eating habits but crank up the amount of physical activity in your life. The smarter way, however, is to combine the two.

Eat better, exercise more. It's that simple.

If you just starve yourself, you're likely to lose weight - and your health! If you are a 90kg person who keeps eating a normal amount of kilojoules but decides to walk briskly each day for three kilometres or so each day, you can expect to lose about 6.5kg (1 stone) in a year.

You don't need to be a rocket scientist to work out that you can substantially increase your rate of weight loss by reducing your intake too.

About three-quarters of the energy you burn every day comes from what your body uses for its basic needs, such as sleeping, breathing, digesting food and reclining.

A person burns up only a small amount of kilojoules with daily activities such as sitting. Any physical activity in addition to what you normally do will burn up extra kilojoules.

The table shown below features averages for a 70kg person. A lighter person burns fewer kilojoules, a heavier person burns more. Exact kilojoules figures are not available for most activities and the figures are averaged from several sources and show the relative vigour of the activities.

The kilojoules spent in a particular activity vary in proportion to one's body weight. For example, a 45kg person burns a third fewer kilojoules, so you would multiply the number of kilojoules by 0.7. For a 90kg person, multiply by 1.3.

Working harder or faster for a given activity will only slightly increase the calories spent. A better way to burn up more kilojoules is to increase the time spent on the activity.

Kilojoule: A kilojoule is 1000 joules, basically units of energy, named after the physicist James Prescott Joule (1818–1889).