A larger weight reduction is necessary to elicit an increase in adiponectin and a decrease in leptin levels

Abstract

We read the article ‘Effects of individual and combined dietary weight loss and exercise interventions in postmenopausal women on adiponectin and leptin levels’ by Abbenhardt et al. 1 with interest. The authors concluded that diet-induced weight loss with or without exercise increased the serum adiponectin concentration and resulted in a reduction in leptin levels 1. The role of adipose tissue for storage of fuel has recently been extended by Ryan and co-workers to include a contribution to whole-body metabolism due to the proteins secreted by this tissue including leptin, tumour necrosis factor-alpha and adiponectin 2. Adiponectin levels are decreased in obesity 3, and cross-sectional studies have shown an inverse relationship between adiponectin and body mass index 3. In addition, adiponectin increases insulin sensitivity, perhaps by increasing tissue fat oxidation resulting in reduced circulating fatty acid levels and reduced intramyocellular or liver triglyceride content 4. Adiponectin has been shown to have a range of anti-inflammatory, antioxidant and anti-atherosclerotic actions 5. Furthermore, plasma adiponectin levels are blunted in conditions that suggest a high cardiovascular disease risk, such as coronary artery disease, type 2 diabetes and obesity, as well as by cigarette smoking 6. Leptin production is mainly regulated by insulin-induced changes in adipocyte metabolism 4, and the primary biological role of leptin appears to be adaptation to low energy intake rather than as a brake on overconsumption and obesity 4. It is expected that weight loss (>20% of body weight) will result in increased adiponectin expression and decreased leptin levels within 6–12 months 3. Indeed, diet-induced weight loss (approximately 20 kg in 24 months) in obese subjects resulted in a significant increase in adiponectin levels 3. In the study by Ryan et al., a 6-month behavioural dietary weight loss (6 kg) programme did not significantly change plasma adiponectin levels 2. Thus, we believe that a large weight loss is necessary to elicit an increase in adiponectin and a decrease in leptin levels. Also, behavioural dietary weight loss programmes should be maintained for a minimum of 12 months. The authors have no conflict of interest to declare.