Is serum leptin related to physical function and is it modifiable through weight loss and exercise in older adults with knee osteoarthritis?

Abstract

OBJECTIVE:To determine the effect of weight loss and exercise interventions on serum leptin and to investigate the relationship of physical function and osteoarthritis (OA) severity with serum leptin in older overweight and obese adults with knee OA. In addition, the study examined if serum leptin predicts weight loss. DESIGN: Longitudinal, controlled clinical trial of weight loss and exercise interventions. SUBJECTS: Community dwelling, older, overweight and obese adults (n ¼ 316; 460 years of age; body mass index Z28.0 kg m À2 ) with symptomatic knee OA and self-reported difficulty in performing selected physical activities were recruited. INTERVENTIONS: Participants were randomized into one of four groups for the 18-month study duration: Healthy Lifestyle Controls, Dietary Weight Loss (Diet), Exercise Training (Exercise), and a combination of Dietary Weight Loss and Exercise Training (Diet þ Exercise). The weight loss goal for the two Diet groups was 5% from baseline at 18 months. Participants in the Exercise groups were trained for 3 days week À1 , 60 min day À1 . MEASUREMENTS: Body weight, body mass index, serum leptin, physical function, and OA severity were measured at baseline, 6 months, and 18 months. RESULTS: Diet and Diet þ Exercise groups lost 5.3 and 6.1% of their weight, respectively, at 18 months with the Exercise group losing 2.9%. There was a significant main effect of weight loss on serum leptin with a decrease in serum leptin averaged across the 6-and 18-month time points for the Diet and Diet þ Exercise groups compared to the other two groups (b ¼ 0.245; Po0.01). No main effect for exercise training was observed. Serum leptin was related to self-reported physical function. In all participants, a mixed model analysis demonstrated that lower levels of baseline serum leptin predict larger weight loss (b ¼ À2.779; P ¼ 0.048). CONCLUSION: Decreases in serum leptin may be one mechanism by which weight loss improves physical function and symptoms in OA patients.

Cross-sectional and longitudinal associations between circulating leptin and knee cartilage thickness in older adults

“…While Iwamoto reported that serum leptin concentration might be related to increases in body weight and total fat mass in postmenopausal women with knee OA, 27 Miller reported that decreases in serum leptin could explain why weight loss improved physical function and symptoms in patients with knee OA. 28 de Boer documented a distinctly higher serum leptin level in end-stage knee OA patients as compared with controls, 5 and we also reported that hip JSN was associated with serum levels of leptin in older adults. 10 In contrast, Yusuf reported that serum leptin level was positively correlated with BMI but was not associated with progression of hand OA, while serum adiponectin was associated with reduced progression of hand OA over time.…”

Is There a Dose‐Response Relationship Between Weight Loss and Symptom Improvement in Persons With Knee Osteoarthritis?

“…Weight loss is associated with reduction in these inflammatory adipokines (37). Furthermore, it is postulated that reduction in serum leptin is one mechanism by which weight loss improves physical function and symptoms in OA patients (38).…”

The impact of obesity on the musculoskeletal system

“…62 The effects of weight loss and exercise interventions on serum leptin were also assessed in the ADAPT cohort. 63 In the ADAPT cohort, serum leptin was significantly reduced by a long-term diet (weight loss) intervention with modest weight loss of 5-6%. Serum leptin was also related to selfreported physical function with higher leptin concentrations related to greater impairments in physical function.…”