Weight loss in obese adults 65years and older: a review of the controversy

Abstract

Obesity in older adults is ubiquitous in many developed countries and is related to various negative health outcomes, making it an important public health target for intervention. However, treatment approaches for obesity in older adults remain controversial due to concerns surrounding the difficulty of behavior change with advancing age, exacerbating the age-related loss of skeletal muscle and bone, and the feasibility of long-term weight maintenance and related health consequences. This review serves to systematically examine the evidence regarding weight loss interventions with a focus on obese (body mass index 30kg/m(2) and above) older adults (aged 65years and older) and some proposed mechanisms associated with exercise and caloric restriction (lifestyle intervention). Our findings indicate that healthy weight loss in this age group can be achieved through lifestyle interventions of up to a one-year period. Most interventions reviewed reported a loss of lean body mass and bone mineral density with weight loss. Paradoxically muscle quality and physical function improved. Inflammatory molecules and metabolic markers also improved, although the independent and additive effects of exercise and weight loss on these pathways are poorly understood. Using our review inclusion criteria, only one small pilot study investigating long-term weight maintenance and associated health implications was found in the literature. Future research on lifestyle interventions for obese older adults should address the loss of bone and lean body mass, inflammatory mechanisms, and include sufficient follow-up to assess long-term weight maintenance and health outcomes.

Keywords: Lifestyle intervention; Obesity; Older adults; Weight loss; Weight maintenance.

Figure 1

Schematic of the systematic selection process to identify relevant studies (Abbreviations: BC= body composition; DXA = dual energy x-ray absorptiometry; CT= computed tomography; MRI=magnetic resonance imaging; RCT = randomised control trial)

Figure 2. Schematic representation of presented pathways and proposed mechanisms

Adipocytes, myocytes and osteoblasts are derived from mesenchymal stem cells, whereas osteoclasts and macrophages are derived from hematopoietic stem cells. Inflammatory cytokines (e.g. Interleukin 6 [IL-6] and tumor necrosis factor-alpha [TNF-α]) originate from obese adipocytes, myocytes, and macrophages. Weight loss results in decreased inflammatory cytokines, leptin, and increased adiponectin which lead to improved metabolic profile. Exercise/muscle contraction results in decreased muscle catabolism through decreased toll-like receptor 4 (TLR-4) and inflammatory cytokines, and increased muscle anabolism through increased mechano growth factor (MGF). Exercise also exerts positive impact on bone mineral density through increased bone formation/decreased bone resorption via mechanical loading. Sclerostin increases in response to unloading by weight loss resulting in decreased bone formation through the Wnt and NF-kB pathways, an effect prevented by exercise. Thus, exercise attenuates the weight loss-induced reduction of muscle and bone mass and lifestyle therapy (weight loss + regular exercise) significantly improves physical function and metabolic profile in obese older adults.