South Africa has the highest overweight and obesity rate in sub-Saharan Africa: seven out of 10 women and four out of 10 men have significantly more body fat than what is deemed healthy, according to a groundbreaking new study published in the medical journal, the Lancet, on Thursday.

These results correlate with a Medical Research Council study, which found that 61% of the South African population is overweight or obese. This is almost double the global rate of nearly 30%, according to the Lancet study.

The Lancet study, which was conducted by the Institute for Health Metrics and Evaluation at the University of Washington, was a first-of-its-kind analysis of data between 1980 and 2013 from 188 countries.

It found that the rise in global obesity rates over the past three decades “has been rapid, substantial and widespread, presenting a major public health epidemic in both the developed and developing world”.

Of the 70% of overweight South African women, 42% are obese, according to the study.

The authors define overweight as a weight-to-height ratio greater than or equal to 25, but lower than 30, while the ratio for obesity is considered higher than 30.

Risk factor for disease

Research has shown that the risk for developing cardiovascular disease, cancer, diabetes, osteaoarthritis and chronic kidney disease increase when a person’s weight-to-height ratio, also called a body mass index, exceeds 23.

Neighbouring sub-Saharan African countries such as Namibia (19.8%), Lesotho (24.1%) and Zimbabwe (33.5%) have significantly smaller proportions of obese women than South Africa. Eritrea only has 4.7% obese women and Ethiopia 1.8% – respectively, about 10 and 20 times less than South Africa.

The study found that men in developed countries had higher rates of overweight and obesity, while women in developing countries exhibited higher rates.

Rates are on the rise among children and adolescents in the developing world, where nearly 13% of boys and more than 13% of girls were found to be overweight or obese. In South Africa, these rates are significantly higher: a fifth of boys and a quarter of girls have unhealthy amounts of fat in their bodies.

Why such high rates in SA?

Over the years, numerous reasons have been debated as to why the South African obesity statistics look so dire. One of the most common reasons cited is the increasing Westernisation and urbanisation of the South African population over the past few decades. Researchers say this is resulting in people living less active lifestyles and consuming more fast food, which has extremely high salt, sugar and fat content.

Some studies have shown that South African women do very little exercise and that many, particularly black women, associate being fat with wealth, health and success, while being thin is associated with being HIV-infected.

The World Health Organisation predicts that in the next 20 years, obesity-driven diabetes across sub-Saharan Africa will double. Research has also shown that undernourished children have an increased risk of becoming obese.

According to a co-author of the Lancet study, Christopher Murray, not a single country has managed to reduce its obesity rate in the past three decades. “We expect obesity to rise steadily as incomes rise in low and middle-income countries in particular, unless urgent steps are taken to address this public health crisis.”

More findings from the Lancet study:

The highest proportion of the world’s obese people (13%) live in the United States;

China and India together represent 15% of the world’s obese population;

Over the 33-year period of research, several countries in the Middle East showed the largest increase in obesity globally. These countries include Bahrain, Saudi Arabia, Oman and Kuwait;

In six countries, all in the Middle East and Oceania – Kuwait, Kribati, the Federate States of Micronesia, Libya, Qatar, and Samoa – the prevalence of obesity in women exceeds 50%. In Tonga, men and women have obesity prevalence over 50%; and

Between 1980 and 2013, the prevalence of overweight or obese children and adolescents increased by nearly 50%.

This article was amended November 3 2016 to remove the following phrase: “a 2011 health survey conducted by pharmaceutical company GlaxoSmithKline … pronounced South Africa ‘the third-fattest nation in the world'”. Africa Check established that the claim made in GlaxoSmithKline was incorrect and unsubstantiated.