According to the Centers for Disease Control and Prevention (CDC), two in every three people who are obese will develop knee osteoarthritis (OA) in their lifetime. Heavy adults who suffer from the physically debilitating condition could significantly reduce their knee pain and increase their walking speed by losing at least 10 percent of their weight, according to a recent study.

Findings published in JAMA reveal that overweight and obese adults who suffer from knee OA could dramatically reduce their fatigue and aches while accelerating their walking speed by adopting an intensive diet and exercise regimen. Researchers from Wake Forest University in North Carolina conducted an Intensive Diet and Exercise for Arthritis (IDEA) study in order to examine whether a 10 percent minimum reduction in weight resulting from diet, with or without exercise, would affect knee inflammation compared to just exercising alone.

A total of 454 overweight and obese participants — 55 years of age or older — who had a body mass index (BMI) between 27 and 41 and suffered from knee OA were part of the 18-month study. The participants were randomized into three groups: diet and exercise, diet only, and exercise only. Those that followed a diet plan had to abide by a weekly meal plan, including up to two meal-replacement shakes a day and a meal between 500 and 750 calories that was low in fat and high in vegetables. At the start of the study, dieters could choose to have to two 300-calorie meal-replacement shakes a day or another meal replacement (such as a protein bar or calorie-controlled prepared meal) and one meal that was 500 to 750 calories and low in fat, USA Today reports. After six months in the trial, the dieters had the choice of slowly getting off the meal replacements and consuming healthy, low-calorie foods.

The participants who followed an exercise regimen had to work out one hour a day for three days a week. These exercises included aerobic walking (15 minutes), strength training (20 minutes), a second aerobic phase (15 minutes), and a cool-down (10 minutes). During the first six months of the trial, the exercises were done at a training facility. After the six months and a two-week transition phase, the exercise group could choose whether they wanted to continue working out at the training facility, do a home-based program, or both.

Lastly, the diet and exercise group followed both the meal plan and exercise program. This group of participants was found to yield the greatest results from the 18-month study. Researchers found that these individuals lost an average of approximately 23 lbs., or 11.4 percent of their initial weight, in 18 months while dieters lost nearly 20 lbs., or 9.5 percent of weight, and those who just exercised lost 4 lbs., or two percent of their body weight. Data confirms that the majority of the weight loss for all participants occurred during the first nine months of the trial and then continued at a moderate rate with no weight regain from any of the three groups.

“The more weight people lost, the greater the improvements,” said Stephen Messier, lead author of the study and a professor of health and exercise science at Wake Forest University, reports USA Today. “Those who lost more than 10% of their starting weight had less pain, better mobility, decreased joint load and decreased inflammation than those who lost less."

The participants in the diet and exercise group reported knee pain reduction by 51 percent, diet group by 25 percent, and the exercise group by 28 percent. However, all three groups were found to increase their walking speed, with the diet and exercise group experiencing the greatest increase.

“When combining weight loss with exercise, patients can safely achieve a mean long-term weight loss of more than 10%, with an associated improvement in symptoms greater than with either intervention alone,” the study authors wrote, Medical News Today reports.

Increased walking speed was found to be a noteworthy discovery for the researchers who report that as adults age, their speed decreases. Adults tend to lose one to two percent of their walking speed for each decade of their life, Messier said. After adults reach age 63, their walking speed begins to decrease by 12 to 16 percent per decade. The lead author of the study marveled at the fact that the participants of the study were able to increase their walking speed at an age where it is decreasing for the elderly.

Knee OA affects more than 10 million Americans, and is known to be the most common cause of disability in the United States. Risk factors for OA include older age, obesity, and joint injuries.