dieting is not enough for weight loss
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Simply reducing caloric
intake is not enough to promote significant weight loss, concludes a new
The research by scientists at Oregon Health & Science University is
published in the April edition of the American Journal of Physiology –
Regulatory, Integrative and Comparative Physiology.
"In the midst of America's obesity epidemic, physicians frequently advise
their patients to reduce the number of calories they are consuming on a
daily basis. This research shows that simply dieting will not likely cause
substantial weight loss.
“Instead, diet and exercise must be combined to achieve this goal,"
explained Judy Cameron Ph.D., a senior scientist at OHSU's Oregon National
Primate Research Center, and a professor of behavioral neuroscience and
obstetrics & gynecology in the OHSU School of Medicine, as well as a
professor of psychiatry at the University of Pittsburgh.
To conduct the research, Cameron and OHSU post-doctoral fellow Elinor
Sullivan, Ph.D., studied 18 female rhesus macaque monkeys at the Oregon
National Primate Research Center. The monkeys were placed on a high-fat diet
for several years. They were then returned to a lower-fat diet (standard
monkey food) with a 30 percent reduction in calories. For a one-month
period, the monkeys'' weight and activity levels were closely tracked.
Activity was tracked through the use of an activity monitor worn on a
"Surprisingly, there was no significant weight loss at the end of the
month," explained Sullivan. "However, there was a significant change in the
activity levels for these monkeys. Naturally occurring levels of physical
activity for the animals began to diminish soon after the reduced-calorie
diet began. When caloric intake was further reduced in a second month,
physical activity in the monkeys diminished even further."
A comparison group of three monkeys was fed a normal monkey diet and was
trained to exercise for one hour daily on a treadmill. This comparison group
did lose weight.
"This study demonstrates that there is a natural body mechanism which
conserves energy in response to a reduction in calories. Food is not always
plentiful for humans and animals and the body seems to have developed a
strategy for responding to these fluctuations," added Cameron. "These
findings will assist medical professionals in advising their patients. It
may also impact the development of community interventions to battle the
childhood obesity epidemic and lead to programs that emphasize both diet and
- ANI / Times of India