Fat Distribution Plays Key Role in Weight Loss
Success in Patients at Risk of Diabetes
‘Abdominal and liver fat are the two most important
factors in predicting whether a lifestyle intervention will be
successful’
Aug. 24, 2010 - Another research project has
confirmed that all fat is not the same, when in comes to people trying
the shed it. Why is it that some people lose weight and body fat when
they exercise and eat less and others don't? German researches used MRI
and magnetic resonance (MR) spectroscopy to provide the answer - and
help predict who will benefit from lifestyle changes.
"You may have two individuals who weigh the same
and have the same body mass index (BMI), but have very different levels
of internal fat," said lead researcher and physicist Jürgen Machann,
Dipl. Phys., from University Hospital Tübingen in Tübingen, Germany.
‘Participants with a greater than 4 inch increase in
waist size from baseline to the third follow-up visit had a 70 percent
higher risk of type 2 diabetes…’
"Abdominal and liver fat are the two most important
factors in predicting whether a lifestyle intervention will be
successful."
Machann and researchers performed MRI and MR
spectroscopy on 243 individuals prior to and nine months after a
lifestyle intervention. The intervention called for a weight loss of 5
percent, reducing fat intake to a maximum of 30 percent of total
calories (including less than 10 percent in the form of saturated fat)
and engaging in moderate physical activity such as walking at least
three hours a week.
Each of the participants, which included 144
females (mean age 44.5 years) and 99 males (mean age 47.3), was
considered at risk of developing type 2 diabetes as a result of obesity,
measured by a body mass index (BMI) of 27 or greater or having an
impaired glucose tolerance or a first-degree relative with the disease.
"Common methods, such as body impedance analysis,
may determine that a body consists of 25 percent fat, but that does not
tell you how the fat is distributed," Machann said.
"BMI is a good measure for obesity but not
necessarily a predictor for health risk, because not only the amount of
fat, but also its distribution are essential. Only by looking inside the
body can you establish the amount of visceral (abdominal) and liver
fat."
MRI allowed researchers to differentiate fatty
tissue from lean tissue throughout the body. MR spectroscopy generated
additional data on the fat content of individual organs, such as the
liver.
Researchers used improved insulin sensitivity to
measure the success of the lifestyle intervention. Individuals with type
2 diabetes do not respond correctly to insulin, a hormone secreted by
the pancreas that aids in metabolism. In pre-diabetes, cells become
resistant to the action of insulin.
After nine months of participating in the lifestyle
intervention, insulin sensitivity improved in 71 percent of the men and
58 percent of the women.
Individuals with improved insulin sensitivity lost
significant amounts of visceral fat (a mean reduction of 19 percent for
women and 20 percent for men) and liver fat (a mean reduction of 35
percent for women and 44 percent for men) while reducing 3 to 5 percent
of body weight.
"The participants who improved their health status
as a result of diet and exercise started out with lower baseline levels
of abdominal and liver fat," Machann said. "In our study, these two
factors predetermined whether or not a lifestyle intervention would be
successful for a particular individual."
Individuals who did not improve insulin sensitivity
as a result of lifestyle changes lost much smaller amounts of visceral
fat (a mean reduction of 4 percent for women and 6 percent for men). The
men also lost less liver fat (a mean of 15 percent), and women gained a
mean of 22 percent in liver fat.
"Our results demonstrate that with MRI and MR
spectroscopy, we can determine who will benefit from dietary changes and
exercise and who will need other interventions," Machann said.
Results of the study are published online and will
appear in the November issue of the journal Radiology.
Collaborating with Machann in the research were
Claus Thamer, M.D., Norbert Stefan, M.D., Nina F. Schwenzer, M.D.,
Konstantinos Kantartzis, M.D., Hans-Ulrich Häring, M.D., Claus
D.Claussen, M.D., Andreas Fritsche, M.D., and Fritz Schick, Ph.D.
Notes:
Source: "Follow-up Whole-Body Assessment of Adipose
Tissue Compartments during a Lifestyle Intervention of a Large Cohort at
Increase Risk for Type 2 Diabetes."
Radiology is edited by Herbert Y. Kressel,
M.D., Harvard Medical School, Boston, Mass., and owned and published by
the Radiological Society of North America, Inc. (http://radiology.rsnajnls.org/)
RSNA is an association of more than 44,000
radiologists, radiation oncologists, medical physicists and related
scientists committed to excellence in patient care through education and
research. The Society is based in Oak Brook, Ill. (RSNA.org)
For patient-friendly information on MRI and MR
spectroscopy, visit
RadiologyInfo.org.
Links to More on Senior
Citizens and Obesity in SeniorJournal.com Archives
With the metric system, the
formula for BMI is weight in
kilograms divided by height
in meters squared. Since
height is commonly measured
in centimeters, divide
height in centimeters by 100
to obtain height in meters.
Example: Weight = 68 kg,
Height = 165 cm (1.65 m)
Calculation: 68 ÷ (1.65)2
= 24.98
People who survive to 70 in reasonable health have
different set of risks and benefits associated with the amount of body
fat to younger people; study questions current BMI guidelines for older
adults - Feb. 1, 2010
Aug. 24, 2010 - Another research project has
confirmed that all fat is not the same, when in comes to people trying
the shed it. Why is it that some people lose weight and body fat when
they exercise and eat less and others don't? German researches used MRI
and magnetic resonance (MR) spectroscopy to provide the answer - and
help predict who will benefit from lifestyle changes. 
Over 12 weeks, they lost about 15.5 pounds, while
others lost about 11 pounds.
More
About BMI
