Effects of energy restriction on neuroendocrine status in obese adults, and possible effects on body composition and strength — ASN Events

Effects of energy restriction on neuroendocrine status in obese adults, and possible effects on body composition and strength (#116)

Amanda (Sainsbury) Salis 1 , Radhika V Seimon 1 , Alice Gibson 1 , Tania P Markovic 2 , Janet Franklin 2 , Elisia Manson 2 , Gareth S Denyer 3 , Ian D Caterson 1 , Jacqueline R Center 4 , Neil A King 5 , Rachel E Wood 5 6 , Imogen Evans 1 , Andrew P Hills 5 7 , Nuala M Byrne 5
  1. The Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, Sydney Medical School, Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
  2. Metabolism & Obesity Services, Royal Prince Alfred Hospital, Camperdown, NSW, Australia
  3. School of Molecular Bioscience, The University of Sydney, Camperdown, NSW, Australia
  4. Osteoporosis and Bone Biology, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia
  5. School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia
  6. Discipline of Medicine, The University of Adelaide, Adelaide, SA, Australia
  7. Mater Mother’s Hospital, Mater Medical Research Institute and Griffith Health Institute, Griffith University, South Brisbane, QLD, Australia
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.