Overweight and obese adults suffering from knee osteoarthritis may benefit more from combined intensive diet and exercise regimes, rather than undertaking diet or exercise regimes separately, according to a study published in JAMA.
Osteoarthritis (OA) is a common degenerative joint disease and the most common form of arthritis. Knee OA is the most common cause of mobility dependency and diminished quality of life, and obesity is a major contributing factor to the disorder.
According to the Centers for Disease Control and Prevention (CDC), two in every three people who are obese will develop knee OA in their lifetime.
Researchers from Wake Forest University in North Carolina conducted an Intensive Diet and Exercise for Arthritis (IDEA) trial in order to determine whether a minimum 10% reduction in body weight as a result of diet, with or without exercise, would have an impact on joint loading and inflammation, compared with just exercise alone.
The research team analyzed 454 overweight and obese individuals aged 55 or older, who had a body mass index (BMI) of between 27-41. All patients suffered from knee OA.
In this 18-month trial, the participants were randomized into one of three groups:
aDiet and exercise
The participants who followed the diet were required to follow a weekly meal plan, including up to two meal-replacement shakes a day and a meal between 500-750 kcal that was low in fat and high in vegetables.
The participants following the exercise plan were required to exercise for 1 hour a day, 3 days a week. This involved aerobic walking (15 minutes), strength training (20 minutes), a second aerobic phase (15 minutes), and a cool-down (10 minutes).
For the first 6 months, exercise was center-based. After a 6-month follow-up and a 2-week transition phase, participants could choose whether they remained center-based, opt for a home-based program or combine both.
Combined diet and exercise best for knee OA
Researchers say that overweight and obese adults suffering from knee osteoarthritis may benefit from combined intensive diet and exercise regimes.
Of the participants, 399 completed the full study and returned for the 18-month follow-up.
Results of the study revealed that average weight loss was higher in the diet-only group and in the combined exercise and diet group, compared with the exercise-only group.
The combined diet and exercise group also showed reduced knee pain, better function, faster walking speed and better physical health-related quality of life, compared with the exercise-only group.
The participants in the combined diet and exercise group showed reduced Interleukin 6 levels - a measure of inflammation - compared with those in the exercise-only group.
Additionally, those in the diet-only group showed greater reductions in knee compressive force, compared with those in the exercise group.
The study authors say that osteoarthritis and other obesity-related diseases put an enormous physical and financial burden on the US health care system. But they note that their findings suggest exercise and diet interventions combined may help to tackle this issue:
"The estimated 97 million overweight and obese Americans are at substantially higher risk for many life-threatening and disabling diseases, including OA.
The findings from the IDEA trial data suggest that intensive weight loss may have both anti-inflammatory and biomechanical benefits; 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"