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
Do microplastics harbour additional risks by colonization with harmful bacteria?
05.04.2018 | Leibniz-Institut für Ostseeforschung Warnemünde
Rutgers-led innovation could spur faster, cheaper, nano-based manufacturing
14.02.2018 | Rutgers University
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Interdisciplinary Research
20.04.2018 | Physics and Astronomy