Sugar tax no instant obesity cure

South Africa has been wrapped up in public and parliamentary debates about the value of the country’s proposed sugar tax. The case made by the government for introducing such a tax centres on our obesity epidemic, which has been fuelled by people consuming huge amounts of sugar.

Obesity shortens a person’s life-span and affects their quality of life. It leads to lifestyle diseases that can give rise to a stroke, blindness, amputation or kidney failure.

Obesity has become a global epidemic, with more than 600‑million adults worldwide classified as obese. The United States leads the pack with a 34% obesity prevalence, followed by Mexico (30%) and New Zealand (about 26%).

The World Health Organisation reports that South Africa has the highest obesity levels in Africa, with 26.8% of people classified as obese. Seychelles has an obesity level of 26.3% and Botswana follows closely behind with 22.4%.

In South Africa, obesity-related lifestyle diseases rival tuberculosis and HIV illnesses in terms of their effects. Research shows that chronic diseases result in one death every hour. About 40% of South African women and 11% of men suffer from obesity, and 25% of teenage girls in rural areas are overweight or obese.

But blaming sugar for obesity neglects the many other factors at play in this complex health issue.

Global studies show there are several factors responsible for someone developing obesity. These include genetic links, lifestyle changes, calorie-dense diets, sleep deprivation and psychological problems.

South Africa would need to investigate these links as part of its plan to tackle skyrocketing obesity rates.

As the world economy becomes more information-based, adults and children spend more time on cellphones, watching TV and on computers or tablets, taking sedentary lifestyles to a new level. For children, this means they have little time for unstructured play or physical activity, which links directly to an increase in chronic, noncommunicable diseases.

According to a study by the Milken Institute in the US, every 10% investment in information and communication technology by a country results in a 1% increase in obesity. In addition, people’s diets have seen massive changes in the past few decades. Energy-dense foods have more calories than nutrients. A high intake of empty-calorie foods may cause people to gain weight, especially if they take in more calories than they burn.

Many working parents have to make long commutes to work and rely on convenience foods packed with salt, sugar and fat instead of home-cooked meals made from fresh ingredients.

Along with the prevalence of obesity these past few decades has come the trend of reduced sleep in adults and children. Worldwide, 85% of people suffer from insomnia. Too little sleep disrupts the normal functioning of our bodies. This includes the hormones that regulate hunger and satiety, which can result in overeating.

Chronic or even partial sleep loss affects hormones, including those that regulate hunger, and satiety-related hormones such as ghrelin and leptin.

There is a close link between how much people sleep and how much they weigh. Researchers studied about 60 000 women for 16 years, asking them about their weight, sleep habits, diet and other aspects of their lifestyle.

At the start of the study, none of the women was obese. After 16 years, those who slept five hours or less each night had a 15% higher risk of becoming obese, compared with women who slept seven hours each night.

Studies spanning five continents have looked at the link between sleep duration and obesity in children. Most of these studies have found a convincing association between too little sleep and increased weight.

A meta-analysis carried out on previous childhood sexual trauma studies, which included 112 000 participants, has shown that being subjected to abuse during childhood entails a markedly increased risk of developing obesity as an adult.

Such studies have shown that victims of childhood sexual abuse are far more likely to become obese adults.

And new research shows that early trauma is so damaging it can disrupt a person’s entire psychology and metabolism. This also links to stigma. For example, local researchers found that the stigma attached to HIV-related disease and weight loss or “thinness” could be fuelling the obesity epidemic among some women. Studies in sub-Saharan Africa have shown that being thin is associated with being HIV positive.

So, if government goes ahead with its plans to implement the sugar tax, it also has a responsibility to fund research into obesity patterns in the country, as well as to educate consumers and create supportive community environments to help people to make healthier lifestyle choices.

Nellie Myburgh is a senior researcher at the Wits Health Consortium at the University of the Witwatersrand. Read the full version of this piece at

The Conversation

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