Whereas justifiable attention is given to the increasing problem of obesity in the general population, far less is known about the relationship between obesity and mortality in older people, or how mortality risk should be estimated. The excess health risks associated with having a high BMI are known to decline with age, yet expert bodies such as the National Institutes of Health and the World Health Organisation have continued to use in older people the same BMI criteria as for other age groups.
Today’s study, published in the American Journal of Clinical Nutrition, was carried out by a team based at the London School of Hygiene & Tropical Medicine. It sought to investigate the association of BMI, waist circumference (WC) and WHR with mortality and cause-specific mortality. The researchers studied 14,833 patients aged over 75 from 53 family practices in the UK; the subjects underwent a health assessment that included taking body measurements and a follow-up (with a median of 5.9 years) for mortality.
The findings confirmed that the current guidelines for BMI-based risk categories overestimate the risks of excess weight in people aged over 75 and are inappropriate for older men and women. This concurs with a previous study that found BMIs of 25-27 not to be a risk factor for all-cause and cardiovascular mortality in those aged 65 and over 1. Most consistently, the data highlighted the risk of having a low BMI, with people in the lowest quintile (less than 23 in men and less than 22.3 in women) demonstrating the highest risk of death for total mortality and for major causes of death. Very underweight men (those with a BMI of under 18.5) were found to be particularly at risk.
‘An explanation for the lack of a positive association with BMI and mortality at older ages is that, in older persons, BMI is a poor measure of body fat’, say the authors. ‘The measurement of weight does not differentiate between fat and fat-free mass, and fat-free mass (especially muscle) is progressively lost with increasing age
Waist circumference (WC) has been proposed as an alternate or additional measure of obesity. The study found no association with waist circumference and mortality. The authors continue: ‘A limitation of WC alone as a measure is that it takes no account of body composition, whereas WHR is a measure of body shape and to some extent of lower trunk adiposity [abdominal fat]. Although it is possible theoretically for high WHR to coexist with thinness, our data show that those with high WHR had higher-than-average waist and average hip circumferences. We conclude that the association observed for WHR and mortality is probably explained by abdominal adiposity’.
The authors recommend that the current BMI-based health risk categories to define the burden of disease related to adult overweight and obesity be reviewed, as they are not appropriate for those over 75. They suggest that WHR should instead be used in this age group because of its positive relation with risk of death, and that attention should also be paid to the problem of underweight in old age.
To interview the authors, please contact the London School of Hygiene & Tropical Medicine Press Office on 020 7927 2073.
Lindsay Wright | alfa
Drone vs. truck deliveries: Which create less carbon pollution?
31.05.2017 | University of Washington
New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)
Computer scientists use wave packet theory to develop realistic, detailed water wave simulations in real time. Their results will be presented at this year’s SIGGRAPH conference.
Think about the last time you were at a lake, river, or the ocean. Remember the ripples of the water, the waves crashing against the rocks, the wake following...
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
29.06.2017 | Physics and Astronomy
29.06.2017 | Life Sciences
29.06.2017 | Health and Medicine