Updated 01 July 2013

Am I obese?

There's a huge difference between being just a little "soft around the edges" and being clinically obese. In which category do you fall, and why?

There's a huge difference between being just a little "soft around the edges" and being clinically obese. Despite what images in the media or your spouse might tell you, you may not have a weight problem.

On the other hand, you might be surprised to find that your weight isn't ideal and that you could be heading for a host of obesity-related problems such as heart disease, diabetes and cancer.

So, how will you know in which category you fall?

There are two simple tools that can be used to determine if you have a significant weight problem: the body mass index (BMI) and the waist-to-hip ratio. Here's how to use them:


To work out your BMI, you need to divide your weight in kilograms by your height in metres squared. This isn't as complicated as it sounds. For example, if you're 1.65m tall and weigh 85kg, you would use the following formula to calculate your BMI:
weight / height squared = 85/1.65 x1.65 = 85/2.72 = 31.25

So, if you weigh 85kg and are 1.65m tall, your BMI = 31.25

Alternatively, you can use our BMI Calculator to do the math for you.

If your BMI is lower than 18, you're underweight and may also be experiencing problems such as anorexia, bulimia or another type of eating disorder.

If your BMI is between 18 and 25, your weight is normal and you don’t need to go on a weight-loss diet, but you should try to maintain your weight at this level to prevent weight gain.

If your BMI is between 25 and 30, you're overweight. You need to try to remedy the situation.

If your BMI is greater than 30, you're obese. You need to do something to reduce your weight as soon as possible.

Waist-to-hip ratio

Another simple tool for determining if you're overweight is to measure your waist and your hip circumferences and then compare the two measurements to each other by dividing the waist measurement by the hip measurement.

For example, if your waist measurement is 110cm and your hip measurement is 120cm, you'll have a waist-to-hip ratio of 110/120 = 0.92. For men, a waist-to-hip ratio exceeding 1.0 indicates obesity. For women, a waist-to-hip ratio exceeding 0.85 indicates obesity.

Once again, use this Waist-to-Hip Ratio Tool to calculate it for you.

If you're female and found that your BMI exceeds 30 and that your waist-to-hip ratio is, for example, greater than 0.85, you have proof that you're obese and that you urgently need to do something about your weight.

Obesity factors

A number of factors make some of us more prone to gaining weight and developing obesity. These include:

  • Socio-economic status: Ironically, people living in western countries with a higher level of income and education are less exposed to the risk of obesity and more inclined to do something about their weight than those who live in poor communities.
  • Urbanisation and westernisation: In rural, agricultural communities obesity is not common because such populations tend to follow low-fat diets, based on unrefined cereals. They also do a great deal of physical work. When these people move to towns and start following a western high-fat diet and expend less energy, their risk of developing obesity increases. South Africans are faced with an explosion in obesity numbers because such a large segment of our population is rapidly moving to cities and adopting western eating habits.
  • Cultural practices and advertising play an important role in making us regard certain foods as desirable, even if they're "fatal" in terms of weight gain. Family practices are also often to blame, for example when parents use food as a reward or pacifier they foster bad eating habits in their children.
  • Genetics can be responsible for 50-60% of the variation in an individual’s amount of abdominal fat. Obesity is known to run in families: if you have one or more obese parents or grandparents, your risk of developing obesity is high.
  • Individual susceptibility is also a factor. There's scientific evidence that suggests certain individuals are less able to burn fat - a situation that predisposes them to obesity.
  • Modern transport and labour-saving devices such as washing machines and vacuum cleaners make our lives easier, but prevent us from using up energy. This also contributes to weight gain.
  • Lastly, preliminary research suggests that obesity can be linked to viral causes in certain people. For example, an American study (2005) showed that up to 30% of obese test subjects were infected with Adenovirus-36 (Ad-36).

Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Read more of her articles.


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