Obesity linked to bad bones, study

[Guest guest]

I thought obsesity was good for bone strength because of the

additional weightbearing?

Obesity linked to bad bones, study

By staff reporter

11/27/2007- The list of health problems associated with obesity

continues to grow, with a new study linking excess body fat with poor

bone health.

Published in the November issue of the American Journal of Clinical

Nutrition, the new study found that the bones of people with high body

fat were eight to nine percent weaker than those of normal body fat

participants.

Obesity has already been repeatedly linked to an increased risk of

heart disease, stroke, diabetes, cancer, and a host of other health

conditions.

These growing health risks have already put significant pressure on

the food industry for the role it plays in promoting unhealthy eating,

pressure which is augmented by these latest findings.

" Obesity is an epidemic in this country, and I think this study is

critical because it highlights another potential negative health

effect that people haven't considered, " said study co-author

, professor of foods and nutrition at the University of Georgia

College of Family and Consumer Sciences.

and his team conducted advanced three-dimensional bone scans on

115 women aged 18 and 19 with normal (less than 32 percent) and high

(greater than 32 percent) body fat.

After adjusting for differences in muscle mass surrounding the bones,

they found that overweight participants had less healthy bones.

said the exact mechanisms by which excess fat hinders bone

strength are unclear, but studies of obese rats show that they produce

more fat cells in the bone marrow and fewer bone cells. Since fat and

bone cells originate from the same precursor, it may be that fat cell

production is favored over bone cell production in obese people.

Childhood obesity could be particularly detrimental to bone health.

" When you're young you have the capacity to change the shape of your

bones, but when you get older you don't have that capacity. And

because of that, childhood obesity could have a significant, long

lasting negative impact on the skeleton, " said.

Obesity is currently thought to affect more than 64 percent of the

US's adult population and 16 percent of children.

The condition, which has been repeatedly linked to increased risk for

heart disease and diabetes, has been the bane of the food industry in

recent years, with food firms often receiving much of the blame for

the nation's increasing obesity rates.

Is adiposity advantageous for bone strength? A peripheral quantitative

computed tomography study in late adolescent females1,2,3

Norman K Pollock, Emma M Laing, Clifton A Baile, Mark W Hamrick,

B Hall and D

1 From the Departments of Foods and Nutrition (NKP, EML, CAB, and RDL)

and Statistics (DBH), The University of Georgia, Athens, GA, and the

Department of Cellular Biology and Anatomy, Medical College of

Georgia, Augusta, GA (MWH)

Background: Whereas excess adiposity is presumed to be advantageous

for the skeleton, studies investigating relations between bone

strength and fat during youth have been equivocal.

Objectives: Relations of percentage body fat (BF) and bone strength

indexes were assessed in late adolescent females, taking into

consideration surrogates of muscle force [ie, muscle cross-sectional

area (MCSA) and bone length]. Bone measurements in the normal- and

high-fat groups were also compared.

Design: Late adolescent females (n = 115; aged 18.2 ± 0.4 y)

participated in this cross-sectional study. Fat-free soft tissue mass,

fat mass, and percentage BF were measured with the use of dual-energy

X-ray absorptiometry. Tibial and radial peripheral quantitative

computed tomography measurements were taken at the 4% (trabecular

bone), 20% (cortical bone), and 66% (for measurement of MCSA) sites

from the distal metaphyses.

Results: Percentage BF was inversely related to radial cortical bone

area, total bone cross-sectional area (CSA), cortical bone mineral

content (BMC), periosteal circumference, and strength-strain index

(SSI) (20% site; all P < 0.05). After control for MCSA and limb

length, negative relations remained between percentage BF and radial

measurements and were also observed at the tibia (20% site).

Unadjusted bone measures were not different between groups. After

control for MCSA, the high- compared with the normal-fat group had

lower bone measures at the 20% site (cortical bone area and cortical

BMC at the tibia, total bone CSA at the radius, and SSI at both the

tibia and radius; P < 0.05 for all).

Conclusion: Excess weight in the form of fat mass does not provide

additional benefits, and may potentially be negative, for adolescent bone.