Effects of energy restriction on neuroendocrine status in obese adults, and possible effects on body composition and strength (#116)
Energy deficit in lean or
obese animals or humans stimulates appetite and reduces energy expenditure,
thereby contributing to weight regain. Often overlooked in obesity treatments,
however, is the effect of energy restriction on neuroendocrine status. Negative
energy balance in lean animals and humans consistently inhibits the
hypothalamo-pituitary-thyroid, -gonadotropic and -somatotropic axes, while
concomitantly activating the -adrenal axis, with emerging evidence of similar
changes in overweight and obese people during severe energy restriction. These
neuroendocrine changes could adversely affect body composition.
In recent years, severely energy restricted diets (e.g. very low energy diets) have emerged as a safe and effective means of managing obesity, at least in the short term, and are being increasingly used. In order to assess their longer-term safety, we are comparing the effects of severe energy restriction (60-70% energy deficit) versus moderate energy restriction (20-30% energy deficit) on neuroendocrine status, as well as effects on body composition and function (fat mass, fat distribution, hepatic fat, lean mass, muscle diameter, muscle strength, as well as bone mass and turnover), for up to 3 years after commencement of either diet (NHMRC 1026005, The TEMPO Diet Trial: Type of Energy Manipulation for Promoting optimum metabolic health & body composition in Obesity).
By using gold-standard methods for the assessment of body composition (i.e. the 4-compartment model, magnetic resonance imaging and spectroscopy), combined with measures of functional strength, the TEMPO Diet Trial will demonstrate whether or not there are any longer-term effects of severely energy-restricted diets on aspects of body composition that influence metabolic and structural health. As our population becomes increasingly obese, from a younger age, it is essential to ensure that methods used to treat obesity are not inadvertently contributing to metabolic or structural problems such as diabetes, cardiovascular disease, falls and osteoporotic fractures.
In recent years, severely energy restricted diets (e.g. very low energy diets) have emerged as a safe and effective means of managing obesity, at least in the short term, and are being increasingly used. In order to assess their longer-term safety, we are comparing the effects of severe energy restriction (60-70% energy deficit) versus moderate energy restriction (20-30% energy deficit) on neuroendocrine status, as well as effects on body composition and function (fat mass, fat distribution, hepatic fat, lean mass, muscle diameter, muscle strength, as well as bone mass and turnover), for up to 3 years after commencement of either diet (NHMRC 1026005, The TEMPO Diet Trial: Type of Energy Manipulation for Promoting optimum metabolic health & body composition in Obesity).
By using gold-standard methods for the assessment of body composition (i.e. the 4-compartment model, magnetic resonance imaging and spectroscopy), combined with measures of functional strength, the TEMPO Diet Trial will demonstrate whether or not there are any longer-term effects of severely energy-restricted diets on aspects of body composition that influence metabolic and structural health. As our population becomes increasingly obese, from a younger age, it is essential to ensure that methods used to treat obesity are not inadvertently contributing to metabolic or structural problems such as diabetes, cardiovascular disease, falls and osteoporotic fractures.