A primate study, 18 female rhesus macaque monkey - on a high-fat diet
for several years - then returned to a lower-fat diet (standard monkey
food) with a 30 percent reduction in calories. During the next month of
observation - no weight loss, but a decline in activity. Further
reduction of food calories in the following month resulted in even less
physical activity.

Three monkeys on a normal diet were trained exercise 1 hour daily, and
these treadmill exercising monkeys did loose weight.

Much of this sounds familiar to readers of Taubes' "Good Calories, Bad
Calories".  I went from 240 pounds to 175 pounds following a summer of
Low Carb plus about 1,000 miles of bicycling in 2004.

Science News

[b] Diet Alone Will Not Likely Lead to Significant Weight Loss, Study
Suggests [/b]

ScienceDaily (Apr. 14, 2010) — Newly published research by scientists at
Oregon Health & Science University demonstrates that simply reducing
caloric intake is not enough to promote significant weight loss. This
appears to be due to a natural compensatory mechanism that reduces a
person's physical activity in response to a reduction in calories.

The research is published in the April edition of the American Journal
of Physiology -- Regulatory, Integrative and Comparative Physiology.
http://dx.doi.org/10.1152/ajpregu.00617.2009

"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 collar.

"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 exercise."

The research was supported by the National Institutes of Health.

Story Source:

    Adapted from materials provided by Oregon Health & Science
University, via EurekAlert!, a service of AAAS.

Journal Reference:

   1. Sullivan et al. A rapidly occurring compensatory decrease in
physical activity counteracts diet-induced weight loss in female
monkeys. AJP Regulatory Integrative and Comparative Physiology, 2010;
298 (4): R1068 DOI: 10.1152/ajpregu.00617.2009

http://dx.doi.org/10.1152/ajpregu.00617.2009