NIH: For the first time in a lab, researchers at the National Institutes
of Health found evidence supporting the commonly held belief that
people with certain physiologies lose less weight than others when
limiting calories. Study results published May 11 in Diabetes. Researchers at the Phoenix Epidemiology and Clinical Research Branch, studied 12 men and women with obesity in
the facility’s metabolic unit. Using a whole-room indirect calorimeter
– which allows energy expenditure to be calculated based on air
samples – researchers took baseline measurements of the participants’
energy expenditure in response to a day of fasting, followed by a
six-week inpatient phase of 50 percent calorie reduction. The researchers
found that the people who lost the least weight during the
calorie-reduced period were those whose metabolism decreased the most
during fasting. Those people have what the researchers call a “thrifty”
metabolism, compared to a “spendthrift” metabolism in those who lost
the most weight and whose metabolism decreased the least.
“When people who are obese decrease the amount of food
they eat, metabolic responses vary greatly, with a ‘thrifty’ metabolism
possibly contributing to less weight lost,” said Susanne Votruba,
Ph.D., study author and PECRB clinical investigator. “While behavioral
factors such as adherence to diet affect weight loss to an extent, our
study suggests we should consider a larger picture that includes
individual physiology – and that weight loss is one situation where
being thrifty doesn't pay.”
Researchers do not know whether the biological
differences are innate or develop over time. Further research is needed
to determine whether individual responses to calorie reduction can be
used to prevent weight gain.
“The results corroborate the idea that some people who
are obese may have to work harder to lose weight due to metabolic
differences,” said Martin Reinhardt, M.D., lead author and PECRB
postdoctoral fellow. “But biology is not destiny. Balanced diet and
regular physical activity over a long period can be very effective for
weight loss.”
More than one-third of American adults are obese.
Complications from obesity can include heart disease, type 2 diabetes
and certain types of cancer, some of the leading causes of preventable
death.
“What we’ve learned from this study may one day enable a
more personalized approach to help people who are obese achieve a
healthy weight,” said NIDDK Director Griffin P. Rodgers, M.D. “This
study represents the latest advance in NIDDK’s ongoing efforts to
increase understanding of obesity.”
The researchers will next study how lean people respond
to increased caloric intake. People interested in participating in
research may call 602-200-5326 or visit www.clinicaltrials.gov
(Clinical Trial # NCT00687115) for information. Support for the study
comes from the intramural research program of the NIDDK.
The NIDDK, a component of the NIH, conducts and supports
research on diabetes and other endocrine and metabolic diseases;
digestive diseases, nutrition and obesity; and kidney, urologic and
hematologic diseases. Spanning the full spectrum of medicine and
afflicting people of all ages and ethnic groups, these diseases
encompass some of the most common, severe and disabling conditions
affecting Americans. For more information about the NIDDK and its
programs, see http://www.niddk.nih.gov.