05 August 2009

The other side of the obesity story

Think of obese South African kids. Junk food and no exercise the main problems? Not so, say researchers. There are kids in poor communities who are obese - and have stunted growth.

This is the picture: one obese kid binges on hamburgers and chips in front of the TV, and another is fat because his mother couldn't afford proper food while she was pregnant.

These are the two sides to the South African childhood obesity story, reflected in alarming national obesity statistics. Research done by Discovery Vitality and the Sports Science Institute of South Africa indicates that 17% of South African children are overweight or obese, while stunting as a result of malnutrition is present in 19%.

There might be some very good reasons why impoverished South African children are succumbing to the obesity epidemic – and junking out on takeaways isn't one of them.

A dangerous combination
Low birth weight, stunted growth and "catch-up" weight gain during the first two years of a child's life form a dangerous mix - one that's often linked to food poverty and undernutrition.

It could set the stage for obesity and future health problems, and with 43% of households suffering from food poverty in this country, it's a stark reality for many South Africans.

Experts are particularly concerned about the combined incidence of stunting and obesity in some of our children. In fact, the issue has been highlighted by a 2006 study published in The South African Journal of Clinical Nutrition.

The study pointed to a high prevalence of overweight (22%) and obesity (24%) among three-year-old children from rural villages in the Limpopo province. A high prevalence of stunting (48%) occurred in the same group, and 19% of children were both stunted and overweight.

This is contradictory, as overweight and obesity have traditionally been linked to overnutrition, while stunting is generally associated with undernutrition. Here, the two occured at the same time in the very same children.

Also of signficance is the fact that the three-year-old Limpopo children were six times more likely to be overweight if they had had a low birth weight.

How the interaction works
How does low birth weight and stunting combine to result in overweight or obesity?

Research seems to show that when pregnant women are malnourished, their children are subjected to so-called "intrauterine undernutrition". This often leads to low weight and stunted growth at birth.

"During their first two years, the infants experience 'catch-up' weight gain, but they don't grow as rapidly in terms of length. Thus, they become relatively overweight, short children," explains Prof John Pettifor from the Department of Paediatrics at the University of the Witwatersrand.

International research studies indicate that catch-up weight gain during the first two years of life often leads to the accumulation of fat around the midriff, paving the way for obesity, insulin resistance and metabolic syndrome later in life.

"It's therefore of great concern that 84% of the young children in the Limpopo study had shown catch-up weight gain by three years of age," Pettifor says.

Early-life nutrition considered
Addressing nutrition in pregnant mothers, thereby addressing intrauterine nutrition, could be an important step in addressing the escalating incidence of obesity among the less privileged communities of South Africa.

Interestingly, a child's diet may also play a role in obesity risk - and in more ways than may seem obvious.

The researchers who worked on the Limpopo study found that the children's diets were typically low in animal protein, high in carbohydrate, low in fat and deficient in certain key vitamins and minerals.

They hypothesise that the lack of animal protein could also have been to blame for the inhibited growth, while the children's high carbohydrate intake allowed for fat deposition and obesity. This hypothesis hasn't yet been proven.

Furthermore, it should be noted that obesity is a complex condition, and that early-life influences are only part of the problem. A shift away from traditional diets to westernised eating patterns, lack of physical activity, socio-cultural factors, education and stress are other contributing factors.

– (Carine Visagie, Health24, March 2008)

- Pettifor, JM. (2006) Combined stunting and overweight in young children - a paradox? The South African Journal of Clinical Nutrition. Volume 19 No. 3.
- Mamabolo, RL, Steyn, NP, Alberts, M. (2006) Can the high prevalence of micronutrient deficiencies, stunting and overweight in children at ages 1 and 3 years in the Central Region of Limpopo province be explained by diet? The South African Journal of Clinical Nutrition. Volume 19 No. 3.

Read more:
Obesity major health risk for kids
Combat childhood obesity


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