Measuring body weight is a quick and simple way of providing a broad picture of our health. Gabrielle Tuscher, a registered dietitian at OT&P medical centre, explains that the scales are especially useful for individuals suffering from comorbidities (conditions that exist at the same time as a primary condition in a patient) associated with their weight.

Severely under- or overweight people are at high risk of secondary illnesses, so regularly keeping track of their weight can help in achieving a healthy body.

But it is a less obvious indicator of health for people whose weight is within an accepted range.

'Weight does not indicate anything about our muscle mass, percentage body fat or fat distribution,' says Chris Ng, a personal trainer at Pure Fitness.

It is a misconception that there is one ideal weight for all people of a similar age, height and gender. This leads people to build goals around achieving a body weight that might not be right for them and unknowingly put their health in danger.

'Body weight is different for each individual; no one size fits all,' Ms Tuscher says. 'It is not a fixed number, but based on a range, depending not only on the individual's height, age and gender but also on muscle mass, exercise levels and possible medical conditions.'

Various methods can be used to calculate levels of health more effectively.

Body mass index

Since weight does not take into account differences in body frames, the American Heart Association has adopted the body mass index (BMI). This measures your health by assessing both your height and weight, indicating if you are the correct weight for your frame. BMI ranges can be used by both genders and generally correlate well with degrees of fatness (see box at right to calculate your BMI).

But the BMI is only one way of measuring your health. If your frame is especially small or large, the BMI calculation might give you an unrealistic picture of your health.

Jane C, a 26-year-old who is 1.6 metres and weighs 53kg, is considered a healthy weight by BMI standards. However, she was diagnosed as being just inches away from clinical obesity.

'My dietician measured my body fat, which was close to 30 per cent,' Jane says.

Her frail frame is a result of genetics, but the fat tests reveal that she isn't as healthy as her body weight suggests.

The same reasoning applies to professional athletes and bodybuilders, who have a high percentage of muscle mass. Because muscle weighs more than fat, bodybuilders may fall into a higher BMI category even though they have a healthy level of body fat.

Body fat composition

For these reasons it is also important for individuals to determine the amount of fat in their bodies compared with lean body mass (muscle, bone, organs and so on).

The body fat percentage helps devise realistic health goals and reminds us that weight loss does not always equal fat loss.

'Looking leaner and more toned is not always about being lighter on the scales,' Mr Ng says. 'You'll get a more realistic evaluation of your health by monitoring body fat rather than weight'.

Many methods of extreme dieting focus on losing weight rather than on reducing body fat, Ms Tuscher says.

'Most slimming methods provide a quick fix and often encourage water rather than fat loss.'

This means that although the scales give a lower reading, it is likely that you are not shedding fat.

Lifestyle changes such as regular cardiovascular exercise, strength training and a well-balanced diet are much more efficient in reaching long-term weight loss goals.

Skin-fold and waist circumference tests are both excellent ways to measure fat percentage and can be easily done by either a registered dietician or certified personal trainer.

The next time you step onto the scales, just remember: aim to control your lifestyle, not your weight.

With that in mind, you will be changing more than just a number.