Knee pain decreased and function increased significantly in overweight or obese adults with knee osteoarthritis (OA) who lost at least 10% of their baseline body weight, and those who combined diet and exercise had better outcomes than those who used diet or exercise alone in a large randomized trial.
The final data from the Intensive Diet and Exercise for Arthritis (IDEA) study were published in the September 25 issue of JAMA.
"Intensive weight loss of at least 10% of body weight is possible and safe in this population," lead author Stephen P. Messier, PhD, told Medscape Medical News. "Overall, diet and exercise together were more effective than either diet or exercise alone. Patients who had diet plus exercise had less inflammation, less pain, better function, improved health-related quality of life, and better mobility. The diet-only group had greater reductions in knee joint loads than the exercise comparison group."
There was a significant dose–response effect associated with weight loss. "People, regardless of group, who lost at least 10% of body weight had significantly less pain, better function, reduced joint loads, and reduced inflammation compared to people who lost between 5% and 10% or less than 5% of their baseline body weight," said Dr. Messier, who is professor and director of the J.B. Snow Biomechanics Laboratory at Wake Forest University, Winston Salem, North Carolina.
The randomized single-blind trial included 454 overweight and obese older community-dwelling adults (age, 55 years or older; body mass index, 27 - 41 kg/m2) with pain and radiographic knee OA. The interventions consisted of intensive diet-induced weight loss plus exercise, intensive diet-induced weight loss, or exercise. The diet and exercise interventions were center-based with options for the exercise groups to transition to a home-based program. Eighty-eight percent of participants completed the 18-month follow-up.
"Our excellent adherence was due to frequent contacts, clear feedback on goals and achievements, and establishing a personal commitment to the study. These same techniques could be used by healthcare professionals with their patients," Dr. Messier said.
The diet intervention was based on replacing up to 2 meals per day with nutritional shakes, plus a 500- to 750-kcal third meal that was low in fat and high in vegetables. The meal replacements were used for the first 6 months, and participants gradually replaced them with low-calorie meals for the remaining 12 months. The diet plan was designed to produce a daily energy-intake deficit of 800 to 1000 kcal/day.
The exercise intervention combined aerobic walking and strength training for 1 hour a day, 3 days a week.
Average weight loss was greater in the diet and exercise group (−10.6 kg; 95% confidence interval, −14.1 to −7.1 kg) and the diet group (−8.9 kg; 95% CI, −12.4 to −5.3 kg) compared with the exercise group (−1.8 kg; 95% CI, −5.7 to 1.8 kg) at the 18-month follow-up.
Compared with the exercise group, the diet and exercise group had significantly less knee pain, better function, faster walking speed, and better physical health-related quality of life. Participants in the diet and exercise and diet groups also had greater reductions in interleukin 6 levels than those in the exercise group.
"All 3 groups had the same reduction in pain after 6 months. It was not until 18 months that the diet plus exercise group separated itself from the other groups, reducing pain by about 50% in the participants who completed the study," Dr. Messier said.
Although exercise has long been prescribed as a therapy for OA and has many beneficial effects, these findings show that exercise alone often cannot overcome some of the effects of being overweight, Farshid Guilak, PhD, told Medscape Medical News.
"Although it is well known that weight loss is a critical aspect of any therapy for overweight people with [OA], these findings further emphasize the need for intensive therapies that focus on reducing weight. At this point, the direct relationships between the decreases in [interleukin 6] or joint loading and the long-term health of the joint are unknown, and additional studies and long-term follow-ups will be needed to elucidate the role of these factors in OA," said Dr. Guilak, who was not involved in the study. Dr. Guilak is the Laszlo Ormandy Professor and vice-chair of orthopaedic surgery and director of orthopaedic research at Duke University Medical Center in Durham, North Carolina, and editor-in-chief of the Journal of Biomechanics.
"This is a very convincing study. All overweight/obese patients with knee OA should join a program with weight loss and exercise. The only matter of dispute is whether obese people may start off exercising right away or should go on [a] diet first not to overload their knees," said Henning Bliddal, MD, from Frederiksberg University Hospital, Frederiksberg, Denmark, who was not involved in the study.
Dr. Messier added, "While the weight loss intervention was successful and their lean mass relative to their new body weight actually increased, the absolute amount of lean mass decreased in both diet groups. Future weight loss studies in the population should try to combat the reduction in muscle mass, perhaps with a more intense strength training component of the exercise regimen."
The study was funded by the National Institutes of Health, the National Institute of Arthritis and Musculoskeletal and Skin Diseases, the National Institute on Aging, the National Center for Research Resources, and General Nutrition Centers. Dr. Messier has given expert testimony fees from Anspach Meeks Ellenberger. One coauthor reported receiving royalties from DonJoy. One coauthor reported receiving consulting fees from MerckSerono, Novartis, Abbott, Perceptive, and Bioclinica; speaker's fees from Synthes and Medtronic; owns stock from Chondrometrics; and received travel expenses from MerckSerono. One coauthor reported receiving consulting fees from Genzyme, Astra-Zeneca, Novartis, MerckSerono, TissueGene, and sanofi-aventis and owning stock from Boston Imaging Core The other authors, Dr. Bliddal, and Dr. Guilak have disclosed no relevant financial relationships.
JAMA. 2013;310:1263-1273. Abstract
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Cite this: Arthritis Knee Pain: Exercise and Diet Tops Diet Alone - Medscape - Sep 26, 2013.