Dec. 21, 2011 -- Obesity is a major risk factor for knee osteoarthritis, and although weight loss is often recommended to reduce painful pressure on joints, not all patients succeed in shedding extra pounds.
Osteoarthritis -- sometimes called "wear and tear" arthritis -- is frequently related to age-related changes in joints. Now a study from Denmark suggests that a very low-calorie commercial diet in which most meals are replaced with a high-protein formula, can help patients with the degenerative joint disorder lose weight safely.
Nine out of 10 obese patients stayed on the 400- to 1,200 calorie-a-day diet for the entire four-month study, losing an average of 30 pounds each.
Researcher Robin Christensen, PhD, tells WebMD that more than half of the patients (60%) also reported improvements in knee pain and mobility after dropping the weight.
He says the findings show that a closely monitored, highly calorie-restricted, formula-based diet can be a safe and effective osteoarthritis treatment, but an arthritis specialist who spoke to WebMD remains skeptical.
“This was a 16-week [trial] which, admittedly, resulted in impressive weight loss. But we don’t know what happened to these patients 6 months later,” says Sharon L. Kolasinski, MD, who heads the division of rheumatology at Cooper University Hospital in Camden, N.J.
Obesity a Major Osteoarthritis Contributor
About 10 million Americans have osteoarthritis and, based on current trends, nearly 6.5 million more adults in the U.S. will be diagnosed with the degenerative joint disease over the next decade.
It is estimated that half of these new cases will occur in people younger than age 65, largely because of the dramatic increase in obesity in recent years.
In the Danish study, Christensen and colleagues recruited 192 obese patients with knee osteoarthritis who were over age 50.
A total of 175 patients followed the formula-based commercial Cambridge Weight Plan for 16 weeks, taking in 420 to 810 calories a day during the initial 8-week formula-only phase of the diet, and about 1,200 calories a day during the final eight weeks, during which one food-based meal was added.
All the patients had weekly sessions with a nutritionist during their time on the diet. During the second phase of the study they were taught healthy eating strategies based on five to six small meals a day.
Cambridge Manufacturing Company, which markets the formula-based diet, co-funded the study.
Christensen says the patients lost mostly fat and not lean muscle mass during their time on the diet, and most showed improvements in vitamin D and vitamin B12 levels. Vitamin D is associated with bone health.
The study appeared online Dec. 21 in advance of publication in the European Journal of Clinical Nutrition.
Expert: Exercise, Weight Loss Both Important
Although Kolasinski agrees that strategies are needed to help obese osteoarthritis patients lose weight, she is far from convinced that very low-calorie diets are the answer.
“Regular exercise and weight loss are optimal, but exercise can make a huge difference even in patients who don’t lose a lot of weight,” she says. “We know that people with osteoarthritis tend to get way too little exercise.”
Kolasinski recommends swimming and other aquatic exercise, which is easy on the joints. But she adds that many other forms of exercise, including yoga, pilates, and resistance training, can be adapted to osteoarthritis patients.
“I have a number of patients doing Zumba, and they love it,” she says.