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dmcfarlane
11-11-2008, 01:50 PM
Dear All,

These days there seem to be a lot of health campaigns lately that urge
us to keep our waistlines under 100 cm (or in some cases under 80 cm).
Unsurprisingly they exhort us to eat healthier foods and exercise more
but the hoardings do not usually give us any indication as to how much
exercise is enough. Sometimes we get told optimistically that only half
an hour a day will fix all our problems. In the field of sports training
one often hears the proud claim that you will never see a fat runner but
so far my research shows that it is merely a myth for people aged over
50.

Presumably these concerns about body weight are based on research that
shows that high carbohydrate "junk food" diets that cause obesity can
also contribute to hypertension, type 2 diabetes, dyslipidemia, coronary
artery disease and metabolic syndrome (i.e. "Syndrome X") as a result of
hyperinsulinemia (Cordain et al, 2003).

The case for frequent exercise is strong; recent research in England has
shown that moderate aerobic exercise over half a year or more results in
a preferential loss in visceral fat (Thomas et al, 2002). However,
earlier research in England had shown that standard anthropometric
measurements "such as skin fold measurements, body mass index, and
waist-to-hip ratio" do not reflect variations in the amounts of total,
subcutaneous and visceral fat in the body (Thomas et al, 1998).
Obviously the usefulness of tape measures tends to be exaggerated.

It is not unusual for research to be based on atypical populations such
as university students, army recruits and professional athletes; ergo
one needs to be skeptical about the application of such research to
older populations. Appropriate exercise can undoubtedly provide
short-term weight loss but it is really feasible for people in the
workforce to do enough exercise to prevent middle-age spread? I have
been researching the topic of age-related weight gain recently but I was
disappointed to find that there is little data applicable to people aged
from 49 to 65 (the current age of the Baby Boomers). Here is my current
summary of research age-related weight gain.

Research at Berkeley has shown that even long distance runners can
become moderately overweight before the age of 30 over 20% of runners
have a BMI of 25 or greater and by the time they are 49 years old more
than 30% have a BMI of 25 or more (Williams, 1997). As Jeffery Kahn put
it weight gain due to age is inevitable and even serious athletes suffer
from middle-aged spread.

Williams suggested that dietary guidelines should either recommend
substantial increases in physical activity over time (if they promoting
an age-neutral adult overweight standard) or accept an age-adjusted
overweight standard if they recommend a constant level of physical
activity over time (ibid).

Later research on the adiposity middle aged males at the Donner
Laboratory showed that vigorous physical activity must increase with age
to prevent middle-age weight gain (Williams and Pate, 2005). Further
research on exercise levels and age-related weight gain confirmed that;
"Age-related weight gain occurs even among the most active individuals
when exercise is constant" (Williams and Wood, 2006).

Worse still even in early middle age the amount of exercise needed to
fight weight gain is prodigious. Men in early middle age (between the
ages of 35 and 44) who only ran about 24 kilometers a week gained about
2 kilograms more weight per decade than those who ran over 48 kilometers
a week (Williams, 2007). These results suggest that after the age of 35
many people would need to devote more than half an hour a day to
exercise (which is the typical amount recommended in guidelines on diet
and exercise). It suggests that people aged over 55 ("Senior Citizens")
would need to devote much more time. If that is the case maybe it is
time for public health campaigns to stop tormenting our older citizens
with unrealistic goals that appear to be based on data for younger
populations.

Has any research on exercise regimes for weight control for people aged
over 55 lately?

Failing that does anyone have any data on typical rates of age-related
weight gain in people aged over 49?

Regards,

David McFarlane MAppSc (Ergonomics)
Ergonomist, WorkCover NSW

References

1. Cordain L, Eades MR, Eades M, (2003), " Hyperinsulinemic diseases of
civilization: more than just Syndrome X", Comp Biochem Physiol A Mol
Integr Physiol, 2003 Sep, 136, (1), pp 95-112.
http://www.ncbi.nlm.nih.gov/pubmed/14527633

2. Thomas EL, Brynes AE, McCarthy J, Goldstone AP, Hajnal JV, Saeed N,
Frost G, Bell JD, (2002), "Preferential loss of visceral fat following
aerobic exercise, measured by magnetic resonance imaging", Lipids, 2000
Jul, 35, (7), pp 769-76. http://www.ncbi.nlm.nih.gov/pubmed/10941878


3. Thomas EL, Saeed N, Hajnal JV, Brynes A, Goldstone AP, Frost G, Bell
JD, (1998), "Magnetic resonance imaging of total body fat", J Appl
Physiol, 1998 Nov, 85, (5), pp 1778-85.
http://www.ncbi.nlm.nih.gov/pubmed/9804581

See "Are you a Tofi? (That's thin on the outside, fat inside)", by Jo
Revill,
The Observer, Sunday December 10 2006:
http://www.guardian.co.uk/science/2006/dec/10/medicineandhealth.health

4. Williams P, (1997), "Evidence for the incompatibility of age-neutral
overweight and age-neutral physical activity standards from runners", Am
J Clin Nutr, 1997 May, 65, (5), pp1391-1396. Abstract
http://www.ncbi.nlm.nih.gov/pubmed/9129467
Full paper http://www.ajcn.org/cgi/reprint/65/5/1391
For an entertaining summary see "Middle-Age Weight Gain: Men Unlikely To
Outrun It" by Jeffery Kahn (April 25, 1997);
http://www.lbl.gov/Science-Articles/Archive/spare-tire.html

5. Williams PT and Pate RR, "Cross-sectional relationships of exercise
and age to adiposity in 60,617 male runners", Med Sci Sports Exerc, 2005
Aug, 37, (8), pp 1329-37.
http://www.ncbi.nlm.nih.gov/pubmed/16118580

6. Williams PT and Wood PD, (2006), " The effects of changing exercise
levels on weight and age-related weight gain", Int J Obes (Lond), 2006
Mar, 30, (3), pp 543-51.
http://www.ncbi.nlm.nih.gov/pubmed/16314878

7. Williams PT, (2007), " Maintaining vigorous activity attenuates 7-yr
weight gain in 8340 runners", Med Sci Sports Exerc, 2007 May, 39, (5),
pp 801-9.
http://www.ncbi.nlm.nih.gov/pubmed/17468577


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