Modest weight loss over two years in overweight or obese middle-aged women may reduce the risk of heart disease and diabetes, U.S. researchers said Wednesday.

In a study of 417 women participating in weight loss programs for up to 24 months, those who sustained a 10 percent or more loss of their body weight for two years reduced their total cholesterol, LDL "bad" cholesterol, HDL "good" cholesterol, triglycerides, insulin, glucose and inflammation markers.

Women who had the highest levels of risk at the start of the study benefited the most from modest weight loss, the researchers said.

"It is challenging to lose weight, but if women commit to losing 10 percent of their body weight and sustain that over time, it can have a large impact on overall risk factors associated with heart disease and diabetes," said co-author Cynthia Thomson, professor in the Mel and Enid Zuckerman College of Public Health and director of the University of Arizona Canyon Ranch Center for Prevention & Health Promotion.

The women, with an average age of 44, weighed nearly 200 pounds (about 90 kilograms) at the start of the study.

According to the researchers, factors that may affect creeping weight gain in middle-aged women include sedentary jobs, repeated pregnancy and the transition to menopause. A large percent of middle-aged American women find themselves weighing much more in their forties than they weighed in their teens.

Women in short-term weight loss programs usually do better with weight loss in the first six months and then they start to rebound, the researchers found.

"Our study revealed the need for healthcare providers to provide women with longer-term support for weight control. It seems to pay off in terms of modifying risk factors for obesity- related disease," Thomson said.

"The good news is that when you lose weight long-term, you just don't move to a smaller dress size, you are actually moving these risk factors markedly and likely reducing your risk of heart disease and diabetes," Thomson added.

The findings were published in the Journal of the American Heart Association.