Low-energy diet–induced weight loss leads to independent losses of leg muscle tissue and absolute knee muscle strength in obese patients with knee osteoarthritis (OA). However, the weight loss is accompanied by increased normalized muscle strength and improved self-reported disability and pain, offering benefits to patients with knee OA.
Henriksen and coworkers studied 159 obese patients with knee OA using data from a body composition analysis and isometric muscle strength testing of the knee. The data had been obtained as part of a randomized controlled trial; measurements were performed before and after a 16-week supervised low-energy diet–induced weight loss intervention.
The patients lost an average of 12.9 kg, or 13% of baseline weight, consisting of 10.9 kg fat mass, of which 3.8 kg was leg fat mass. Total lean body mass was reduced by 1.9 kg, of which 0.785 kg was leg lean mass. Absolute muscle strength decreased by about 3% or 4% after the weight loss; body mass–normalized muscle strength increased by 11% to 12%. Leg lean mass was significantly related to muscle strength at baseline.
The authors suggested that weight loss efforts in patients who have knee OA be combined with efforts to restore or add muscle mass.