For many adults, weight gain is slow and steady, but new research suggests that even a few extra kilograms can boost your risk of chronic diseases such as type 2 diabetes and high blood pressure.
"People don't become obese overnight," said study lead author Dr Frank Hu. He's a professor in the departments of nutrition and epidemiology at Harvard T.H. Chan School of Public Health in Boston.
"On average, people gain about a half a kilogram to a kilogram per year. Most people gain weight all the way to 55 and up," Hu said. "But once you cross the obesity threshold, it's difficult to go back. This study provides very strong evidence that prevention of weight gain is very important."
In South Africa, the problem of obesity in adults deserve attention as we have the highest overweight and obesity rate in sub-Saharan Africa, with up to 70% of women and a third of men being classified as overweight or obese, according to the Heart and Stroke Foundation South Africa.
Increased risk for disease
The researchers found that for every five kilograms gained, the risk of diabetes went up 30%. The same weight gain was linked to a 14% increased risk of high blood pressure and an 8% higher risk of heart disease or stroke.
Each five kilogram gain was also associated with a 6% increased risk of an obesity-related cancer, a 5% higher risk of dying prematurely, and a 17% decrease in the odds of healthy ageing. For those who gained significantly more weight, the researchers found dramatic rises in the risk of chronic illness. For example, for people who gained 22 kilograms or more, the odds of type 2 diabetes spiked by 10-fold compared to those who kept their weight relatively stable over the years.
The risk of high blood pressure more than doubled, and the risk of developing heart disease or stroke was almost twice as high, according to the study. However, the research did not prove that weight gain caused these conditions.
The information came from two large-scale studies of health professionals in the United States. They included almost 93 000 women whose health was followed for 18 years, as well as more than 25 000 men whose health was followed for 15 years. At age 55, the average weight gain for women was 13 kilograms and for men it was 10 kilograms. The findings were published online in the Journal of the American Medical Association.
"I think one of the key periods for weight gain and weight retention is during pregnancy and the postpartum periods. There's a significant disparity in the difference in excessive weight gain in women than men, and whether this explains that difference isn't clear," said Dr William Dietz, chair of the Global Center for Prevention and Wellness at George Washington University in Washington, D.C.
Prevention better than cure
"Adult weight gain is not a benign condition. We need to help health care providers learn how to treat people with obesity," he said. On an individual level, both Hu and Dietz recommended monitoring your weight on a regular basis, especially during life transitions, such as getting married or becoming a parent. Step on the scale to see what you weigh, measure your waist circumference or pay attention to how your clothes fit. If you notice a change, get your weight in check sooner rather than later.
Although it's never too late to gain health benefits from losing weight, it becomes much harder to take weight off and keep it off the heavier you get. "If the dam is already open, the flood has already happened and it's extremely difficult to rebuild the whole damn instead of repairing it," Hu said.
"Prevention is much more important and much more effective. Health professionals should pay attention to even modest weight gain," he said.
Obesity and diseases
Strategies to combat obesity
Gender differences in obesity