Sixty one percent of South Africans are overweight, according to a survey.

Cape Town was the worst affected with 72 percent of those surveyed there overweight, obese or morbidly obese. This was followed by Pretoria (68 percent), Johannesburg (59 percent) and Durban (52 percent).

GlaxoSmithKline interviewed 500 people in the study.

It said people were overweight (pre-obese) when their Body Mass Index - a statistical measure of body weight in kilograms divided by height in metres square - ranged between 25kg/m2 and 30kg/m2, obese when this was more than 30kg/m2 and morbidly obese when it wass more than 40kg/m2.

Of those surveyed, 47 percent said the government should play a more active role in targeting obesity, and 46 percent felt obesity would economically affect South Africa.

The survey found that 60 percent of obese, and 62 percent of morbidly obese people considered themselves merely overweight; 49 percent of South Africans did not exercise; 71 percent had never dieted; and that lifestyle, food, poverty and demographics played a role in the weight of the nation.

Of those interviewed, 65 percent had the perception that healthy food was more expensive than unhealthy food; 39 percent looked at cost when purchasing food; and 87 percent ate a home cooked dinner.