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26 April 2011

Why is SA so fat?

A recent survey said that South Africans are the third fattest nation in the world. Why are we so fat? DietDoc comments.

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A recent survey said that South Africans are the third fattest nation in the world. Why are we so fat? DietDoc comments.

After a week of being bombarded with newspaper headlines and TV news reports on the latest national health survey undertaken by GlaxoSmithKline (GSK) that pronounce South Africans as "the third fattest nation in the world", most of us are probably in a state of shock. If, as the study reports, most South Africans, even those who suffer from overweight and/or obesity, are in denial and regard themselves as "healthy", then these revelations must at least make us think about weight issues.

The basic findings - obesity statistics

The basic findings of the GSK survey that was conducted with 500 adults in our four largest cities, are as follows:

  • Up to 2/3 of adult women are obese and 61% of adults are overweight, obese, or morbidly obese.

  • In the present survey, Cape Town had the highest incidence of overweight/obesity (72%), followed by Pretoria (68%), Johannesburg (59%) and Durban (52%).

The Medical Research Council (MRC) also published a report in 2007, which cited that 56% of adult women, 29% of adult men were overweight/obese and 17% of children under the age of 9 years in this country are overweight. Ironically overweight and malnutrition/stunting can occur in the same families and sometimes even in the same individuals.

Possible reasons for this obesity epidemic

There are many possible reasons for the unprecedented obesity epidemic we are experiencing in South Africa at present. Based on the scientific literature, three primary factors may play a vital role, namely:

  • Malnutrition and low birthweight (The Barker Hypothesis)

  • Rapid westernisation and urbanisation (The Thrifty Gene Theory)

  • Physical inactivity (The couch potato syndrome)

Let's briefly consider each one of these factors:

The Barker Hypothesis

In the 1980's Dr Barker proposed the following hypothesis (theory) "poor nutrition in early life increases susceptibility to the effects of an affluent diet" in later life leading to type 2 diabetes, hypertension, cardiovascular disease, cancer, and metabolic syndrome. It has also been found that undernutrition (both before birth and for the first 2 years of life) was one of the main reasons why women then have babies that are underweight at birth. Such babies who enter the world at a disadvantage, will be inclined to gain more weight when they eat a high-fat, high-sugar diet, than children with a normal birthweight. Undernutrition before and after birth, can therefore, have serious long-term health, education and economic consequences that can undermine a country's progress for up to three generations. So one of the reasons why South Africans are facing an obesity epidemic may well be because so many of our mothers suffer from a severe lack of nutritious food before giving birth. Poverty and malnutrition are, therefore, factors that must be addressed before we can eradicate obesity.

The Thrifty Gene Theory

In 1962, Dr James Neel, theorised that human beings have for millennia been adapted to store energy in the form of fat during times of plenty (which were once very rare) for times of starvation (which were once very frequent). In other words, we humans have "Thrifty Genes" which squirrel away any energy we ingest just in case we have to face starvation at a later date. Now when individuals with thrifty genes are exposed to the bounty of a modern western diet, these thrifty genes continue to store as much energy as possible in the form of fat thus causing obesity.

Our indigenous populations were often faced with starvation and energy-dense foods rich in fat were very scarce commodities, but with rapid urbanisation and westernisation, millions of South Africans are now being exposed to high-fat diets which their thrifty genes cannot cope with.

Physical inactivity

Even 30 years ago, most South Africans were a great deal more active than they are today. Every feature of modern life, has made life easier for all of us. We use public transport (taxis, trains, buses), drive cars, ride on escalators, use all manner of time-saving gadgets, and no longer "work by the sweat of our brows!" Added to this, most schools no longer feature compulsory physical education classes and the majority have no sports facilities. Then there are the combined plagues of TV and PCs. These inventions have revolutionised our lives and we can no longer live without them, but they have also turned us into couch potatoes.

Take the World Cup 2010 as an example. A few energetic soccer stars played their hearts out while we and the rest of the world spent hours every day sitting glued to our TV screens, not only doing nothing physical, but compounding the problem by drinking beer and munching fast-foods and fatty snacks.

Next week we will look at the psychological findings of the GSK survey and some possible solutions to the vast dilemma of overweight we are facing in South Africa.  

- (Dr IV van Heerden, DietDoc, September 2010)

References:

Barker DJ, Osmond C (1986). Infant mortality, childhood nutrition, and ischaemic heart disease in England and Wales. The Lancet, 1(8489):1077-81

Joubert J et al (2007). Estimating the burden of disease attributable to excess body weight in South Africa in 2000. SAMJ, 97(8):683-90

Pyhtila H (2007). Thrifty genes. Skade T. SA the third fattest nation in the world. Pretoria News, 9 September 2010, p3

Victora CG et al (2008). Maternal and child undernutrition: consequences for adult health and human capital. The Lancet, 371(9609):340-57.)

Any questions? Ask DietDoc

 
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