Combating visceral obesity through lifestyle interventions

Abstract

Obesity is now declared a global pandemic with more than 10% of adults worldwide being obese. Obesity is a risk factor for a multitude of non-communicable diseases, which also incurs additional healthcare costs and hinders productivity of the labour force. Current obesity management guidelines recommend the initiation of lifestyle interventions incorporating diet, physical activity, and/or behavioural therapy as the first-line treatment strategy once overweight/obesity is diagnosed. While both diet and physical activity are effective measures against obesity by inducing a negative energy balance, their comparative efficacy remains to be elucidated.

It was identified that the excess accumulation of visceral adipose tissue contributes to the incidence of non-communicable diseases via inducing insulin resistance and chronic low-grade inflammation. While individuals with obesity have unfavourably large amounts of visceral fat, normal-weight individuals are susceptible to visceral obesity as well. Overweight/obesity is diagnosed by body mass index, while central obesity is diagnosed by waist circumference, which is considered a robust surrogate marker of central fat accumulation. The effects of lifestyle interventional strategies on visceral adiposity in general and central obesity therefore warrant investigation. In practice, physical activity and diet are typically prescribed as exercise and caloric restriction respectively. Both approaches induce a negative energy balance by either an increase in energy expenditure (exercise) or a decrease in energy intake (caloric restriction). While the effects of exercise and caloric restriction on visceral adipose tissue are well-documented, whether such effects are proportional to the net energy deficit remains unknown. Furthermore, the dose-response effects of exercise versus caloric restriction on visceral adiposity have yet to be properly compared.

A systematic review and meta-analysis was thus undertaken to compare the effects of exercise and caloric restriction on visceral adiposity. Consistent with the current literature, both aerobic exercise and caloric restriction reduce visceral adipose tissue. In addition, exercise also produces a dose-response effect on visceral adipose tissue, whereas the effect of caloric restriction appears to be independent of the level of net energy deficit induced.

Additionally, longitudinal changes in visceral adipose tissue area during an ongoing randomized controlled trial of high-intensity interval training in adults with central obesity were estimated by dual-energy X-ray absorptiometry. Once-a-week high-intensity interval training reduced visceral adiposity in adults with central obesity. This thesis illustrates that while both exercise and caloric restriction are efficacious for obesity management, minimal participation in exercise might be sufficient for ameliorating visceral obesity, thereby stressing the importance of adopting exercise in addition to a physically active lifestyle coupled with a healthy diet.