Obesity May Make Muscles Gather Fat
Muscles Might Be 'Programmed' by Obesity to Store Fat, Study Shows
Oct. 11, 2005 -- The muscles of obese people may welcome fat with open arms,
new research shows.
Severely obese people have three times as much of a fat-building enzyme
called SCD1 in their muscle cells than lean people, scientists report.
That could be one reason why it's often hard to permanently lose weight
through diet alone.
"While these findings may be somewhat discouraging news for those
wishing to reverse obesity through dietary interventions, they also highlight
the importance of exercise," says researcher Deborah Muoio, PhD, in a news
Exercise is known to produce big changes in muscle metabolism, explains
Muoio. She works at Duke University's Sarah W. Stedman Nutrition and Metabolism
The study appears in Cell Metabolism.
The researchers studied muscle cells from lean and obese women. The obese
patients were matched to lean patients of the same age and race.
The lean women had a BMI (body mass index) of 25 or less. The obese women in
the study had a BMI of 35 or more. According to CDC provides guidelines for BMI, 18.5 to 24.9 is normal, 25.0 to 29.9 is
overweight, and 30 or more is considered obese.
First, the researchers checked SCD1 levels in participants' muscles. They
found three times as much SCD1 in the muscles of the obese women studied.
Next, the scientists did some lab tests that made the lean women's muscle
cells produce more SCD1. That pushed those muscle cells towards fat
accumulation, the study shows.
Exactly why obesity and SCD1 went hand in hand isn't known. It's not clear
which came first, the obesity or the rise in SCD1. Did the obesity cause SCD1
to rise, or vice versa?
The researchers outline one possibility.
The body's recipe for making SCD1 is stored in genes. Becoming obese might
switch on those genes, ramping up SCD1 production and programming muscles to
Once those genes are on, they may stay on, the researchers note, citing
studies of animals and research on big groups of people (epidemiological
It might be possible to create drugs that target muscle SCD1, the
researchers note. They also want to see if physical activity can help lower
SCD1 or modify its effect in obese people.
If you don't want to wait for those results, know that physical activity is
recommended across the board for many reasons besides lowering weight
(including heart and bone health). Get your doctor's blessing before starting a
new fitness program, especially if you've been overweight or idle.