Being overweight as an infant increases the risk of being overweight as a child, which in turn increases the risk of being overweight as an adolescent and adult. The results from the largest and longest-running longitudinal birth cohort study, the Birth to Twenty study in Soweto, showed that obese girls between the ages of four and six were 42 times more likely to be obese in their teens compared with their peers of normal weight.

The first step is to understand childhood obesity. The most obvious causes are overeating and underexercising. But like all chronic diseases, the root causes of childhood obesity run much deeper. The complex causes can be genetic, biological, psychological, social, cultural, environmental and economic.

We inherit our genes from our parents, and it has been estimated that 40% to 70% of our chance of having obesity is due to our genes. However, this can be modified by environmental factors such as our life choices and habits including healthy eating and physical activity.

Both children of overweight parents and children subjected to malnutrition during pregnancy or infancy are likely to become obese later in life. In fact, mounting evidence suggests that the origins of childhood obesity can be found as early as the first 1,000 days – from conception to age two. Several risk factors during this period include higher maternal pre-pregnancy body mass index, maternal excess gestational weight gain, high infant birth weight and accelerated infant weight gain are consistently associated with later childhood obesity.

On the other hand, breastfeeding has been described as a protective factor, and the more exclusively and the longer children are breastfed, the greater their protection from obesity.

Studies have also shown that stunting or short stature in children is associated with the increased risk for obesity during adulthood. Children with stunting have lower resting energy expenditure compared with non-stunting children. Stunted children also have higher respiratory quotient and carbohydrate oxidation but lower fat oxidation. These results might explain why stunted children easily become obese, which is due to lower fat oxidation leading to the tendency to store fat.

The population group that is most vulnerable to the obesogenic environment we live in is children. What does this environment look like? Unhealthy foods at supermarket tills, on phones or billboards, increased screen time and sedentary behaviour, cultural beliefs such as expectations to be voluptuous, or poor knowledge about healthy foods.

Poverty in South Africa has also been associated with a change in food consumption patterns whereby healthier foods, such as fruits and vegetables, are more expensive than energy-dense junk foods. Energy-dense foods are high in fat and sugar but low in vitamins and minerals, and unfortunately these become the foods of choice for those living in poverty.

The obesity epidemic mirrors these changes in the food environment. Once associated with Western diets, the increase in processed foods is now seen in many low- and middle-income countries and is undermining local diets. Easily available sugary drinks and junk food at schools contribute to children overindulging in unhealthy food. A child’s sugar intake should be no more than 100 calories from added sugars – 25 grams of sugar or fewer than six teaspoons a day. It is very easy to get these numbers wrong. A 330ml can of sweetened fizzy cold drink contains on average seven teaspoons of added sugar and 139 calories from added sugar (already more than the daily quota).

Parents, as the biggest influence on their children, should introduce healthy eating habits from six months onwards and lead by example. Dietary behaviours develop in the early years. During the second year of life children share their food environment with parents and siblings. This shared “family food environment” influences children’s dietary intake and provides a fundamental target setting for improving their eating behaviours.

Parents also need to negotiate an activity plan with their children. This is likely to involve television viewing time, which can be used as a reward for being active. There are many chores around the house that involve physical activity and these can also be included in a daily activity plan. Obviously, compliance will be best when the child is involved in activities that he/she enjoys, so efforts should be made to maximise these opportunities.

There is no singular solution to obesity, and involvement of all sectors is needed. The food industry is a vital factor in any potentially successful long-term strategy to prevent obesity. By producing new products low in energy density and improving the nutritional quality (and reducing the energy content) of existing products, as well as through advances in responsible marketing and labelling, the food industry can provide foods that are lower in energy but higher in essential nutrients.

The Heart and Stroke Foundation South Africa will continue to advocate at all levels a healthier environment and create public awareness around childhood obesity. The Heart Mark Programme is one such tool used to make it easier for parents to make healthier choices when faced with a variety of options at the grocery store. It helps them to identify products that contain less added sugar, salt and unhealthy fats, and more fibre compared with other similar products.

The food industry is not the sole factor. The government has shown intent by announcing a tax on sugar-sweetened beverages and draft legislation to restrict the advertising of unhealthy foods to children. Swift and effective implementation of these policies is vital.

We are also in the middle of a Covid-19 pandemic which has layered crisis upon crisis. Thankfully, children are rarely seriously affected by medical complications from the virus. However, there is some indication that young people with obesity are at higher risk of severe outcomes. During this time it is vital to ensure policies to promote child health are included in the government’s agenda.

The complexity of the obesity epidemic is often cited to explain the little success in turning the tide and perhaps as an excuse not to make the changes we know are necessary. The WHO Report on Ending Childhood Obesity clearly outlines a comprehensive action plan. Recommendations include addressing norms, treating children who are already obese, promoting healthy foods and physical activity, improved preconception and pregnancy care, healthier school environments, and curbing the marketing of unhealthy foods.

The Department of Health has incorporated these guidelines into its own strategy for the prevention and control of obesity. The strategy singles out childhood obesity as a specific area of focus. Clearly, early interventions should already be addressed during pregnancy and infancy. Modifiable risk factors in the first 1,000 days can inform future research and policy priorities and intervention efforts to prevent childhood obesity.

The president of the World Obesity Federation, Professor Ian Caterson, calls for decisive action: “If governments hope to achieve the WHO target of keeping child obesity at 2010 levels, then the time to act is now.” 

We can end the childhood obesity epidemic if we act together.

If we want to have a real impact on childhood obesity in South Africa, we need to work together to address its many root causes and acknowledge that everybody has a part to play. An urgent and comprehensive approach including parents, the food industry and government is needed to reverse the epidemic. DM

Hayley Cimring (BSc)(Med)(Hons) is the Nutrition Team Leader at the Heart and Stroke Foundation South Africa.