Obesity is on the rise among black women in South Africa, possibly in part due to fears of looking like an AIDS patient, a top health expert on Friday.

Tessa van der Merwe of the International Association for the Study of Obesity said around one in three black South African women is now seriously overweight as new factors bolster a traditional sense in the black community that big is beautiful.

“Regretfully, there is also a perception that if a black woman is thin, she might have HIV/AIDS or that her husband can’t afford to feed her well,” van der Merwe said in a statement.

South Africa has one of the world’s worst HIV/AIDS caseloads, with an estimated 5 million of its 45 million people infected with the virus. It also has one of the world’s highest rates of violent crime.

Studies show that South Africa has weight problems across all race groups, with half of women and one third of men overweight. Those levels are just 20 percent lower than in the United States, regarded by many as the world’s fattest country.

But black women are the most seriously effected and 30 percent are now clinically obese, van der Merwe said, adding that for many regular, high-intensity exercise routines were not part of the picture.

“There is the reality - it simply isn’t safe to walk around,” the researcher said.

“We should be convincing black women that weight loss has a markedly helpful effect on health,” she said, noting a traditional fatty diet among black women.

Van der Merwe, who heads South Africa’s first obesity clinic and addressed a major gastroentorology congress in South Africa this week, said rising obesity was causing health problems such as heart disease, hypertension and diabetes.

“When being overweight is seen as a sign of health and wealth, it is extremely difficult to change this perception,” van der Merwe said.