All Calories Are Not Created Equal
Researchers Say Low-Carbohydrate Diets Have Metabolic Edge
NEW YORK, Aug. 13 /PRNewswire/ -- In a paper published last week in the
Nutrition Journal, researchers from SUNY Downstate Medical Center show that
low-carbohydrate, high-protein diets can be expected to be more effective
for weight loss than low-fat diets. Their supposition goes against long
standing prejudices of the nutritional community which for years have
claimed that only calories count in the battle to lose weight.
"There are numerous examples of low-carbohydrate diets being more effective
than low-fat diets with the same number of calories. It doesn't always
happen but it can happen," said Dr. Richard Feinman of the Department of
Biochemistry, SUNY. "The nutritional establishment has been reluctant to
accept this, because they say it violates the laws of thermodynamics.
However, they have not really looked seriously at thermodynamics. If they
had, they would see that these results are possible, and according to the
second law of thermodynamics, are also to be expected."
Feinman and Fine reviewed the existing literature on studies that compared
low-carbohydrate and low-fat nutritional approaches. In doing so, they found
a sufficient number of reports in the literature to establish the existence
of a metabolic advantage. Clinical studies from such well-established
research facilities as Duke and Harvard(1)(2), among others, were reviewed
and analyzed. The researchers tabulated results from 10 studies,
demonstrating that low-carbohydrate diets can lead to greater weight loss
than isocaloric low-fat diets.
To explain this metabolic advantage, Dr. Feinman and Dr. Eugene J. Fine
suggest that carbohydrates make an efficient fuel for the body, whereas
protein does not.
"Your brain needs glucose to function properly," Feinman said. "There's no
argument about that. Now, this glucose can come from dietary carbohydrates,
but your body can make glucose from protein and, to a much lesser degree,
from fat. However, the process of making glucose from protein is
inefficient, and to get the extra energy needed, your body will burn the fat
that it has already stored. I think that's the bottom line."
The researchers stress that the human body is not a storage locker. They
compare it to a machine, and the efficiency of the machine is controlled by
hormones and enzymes, which are impacted by nutrients. Carbohydrates
increase insulin and other hormones that regulate enzymes which can lead to
storing fat rather than burning fat.
"Of course, people are different" said Dr. Eugene Fine, a professor of
nuclear medicine at Downstate and Jacobi Medical Center in the Bronx. "But
many people are sensitive to the effects of carbohydrates and for them, a
low- carbohydrate diet is going to work well."
The practical point is that getting rid of the idea that "a calorie is a
calorie" opens the door for serious research into what kind of diets will be
most effective and which people will benefit most.
"This is important," Feinman explain "because millions of people are
seriously trying to lose weight on low-carbohydrate diets, and instead of
being given directions on the best way to do this, they have been largely
discouraged by health professionals and self-appointed expert groups. The
obesity epidemic is too important to allow this to happen."
(1) Westman, E.C., Mavropoulos, J., Yancy, W.S., et al., "A Review of
Low-Carbohydrate Ketogenic Diets", Current Atherosclerosis Reports,
5(6), 2003, pages 476-483.
(2) Greene, P., Willett, W., Devecis, J., et al., "Pilot 12-Week Feeding
Weight-Loss Comparison: Low-Fat vs Low-Carbohydrate (Ketogenic)
Diets," Abstract Presented at The North American Association for the
Study of Obesity Annual Meeting 2003, Obesity Research, 11S, 2003,
page 95OR.
SOURCE SUNY Downstate Medical Center
CO: SUNY Downstate Medical Center