Scientists from around the world gather to present research on the physiological challenges imposed by starvation.
At a time when ‘fasting’ is the latest diet trend, comparative physiologists, who study the effects of food limitation in various situations and systems, have gathered today [23 July 2013] as part of the 37th International Union of Physiological Sciences (IUPS) congress, in Birmingham. People who have taken up this diet will be pleased to hear that positive effects have been found in studies, within a reasonable timescale.
Speaker Krista Varady, University of Illinois, Chicago, USA, says, ‘Recent findings suggest that alternate day fasting (25% energy intake for 24 h, alternated with ad libitum feeding for 24-h) does reduce body weight, visceral fat mass, and several cardiovascular disease risk indicators in humans, within 3-6 months.’
The researchers have also taken a step closer into explaining why fatty acid composition changes in response to starvation.Teresa Valencak, Veterinary University Vienna, Austria, says:
‘While the decrease in fat content during fasting is consistent in vertebrates, changes in fatty acid composition during times of poor energy supply are poorly understood. By thoroughly reviewing the original literature that is available on the topic, we have identified two processes that can explain the changes in fatty acid composition during starvation: a) selective mobilization of fatty acids from fat cells and b) changes in lipid composition.’
The research in this field has also required the development of new experimental techniques.
Marshall McCue, St. Mary’s University San Antonio, Texas, USA, says, ‘My research uses an emerging approach; using a stable, heavy isotope of carbon (13C) to artificially label the different nutrient components (protein, lipid, and carbohydrate) in the bodies of animals. As the fasting animal oxidizes different nutrients these 13C atoms are excreted in the breath and can be measured across time to quantitatively model how the body switches among the three classes of nutrients. This technique is non-invasive and provides improved temporal resolution to previous methodologies.’
The physiological challenges to homeostasis – the process used by the body to maintain a stable internal environment – imposed by fasting and starvation have been key drivers in the major mass extinctions in past times so it is important to fully understand the underlying mechanisms.
Hank Harlow, University of Wyoming, Wyoming, USA, says, ‘The research we have conducted shows how hibernating bears orchestrate cardiovascular, respiratory, digestive and excretory systems to conserve skeletal muscle during 5 months of immobility and food deprivation. Bears enter metabolic depression, recycle their urinary nitrogen back into muscle and exhibit muscle contractions during the winter to stay strong.’
The fasting studies also have wider implications than a solution to weight loss. Hank Harlow, University of Wyoming, Wyoming, USA, says, ‘These findings have profound human application to long distance space travel, hospital confinement and sports medicine.’
The speakers at the symposium are contributors to the book “Comparative Physiology of Fasting, Starvation, and Food” edited by M.D. McCue, which provides a compendium on the question.
ENDS
Notes for Editors
1. Prof McCue and Prof Valencak’s symposium “Physiology of fasting and starvation” at the IUPS Congress in Birmingham (ICC), Tuesday 23 July, 9.30 – 11.30, Hall 1, The ICC, Birmingham
2. Congress of the International Union of Physiological Sciences (IUPS), 22-26 July, Birmingham
The congress will bring together over 3000 physiologists from all corners of the globe to attend over 100 symposia and 30 keynote lectures. The congress has been running since 1889 and was started in an effort to promote physiology, encourage the interchange of ideas, and afford physiologists the opportunity to know one another personally. www.iups2013.org
Contacts
Symposium organisers:
Marshall McCue: mmccue1@stmarytx.edu
Teresa Valencak: Teresa.Valencak@vetmeduni.ac.at
The Physiological Society (hosts of IUPS 2013):
Lucy Holmes, Media and Communications Officer
+44 (0)20 7269 5727, +44 (0)7917 610 731, pressoffice@physoc.org