Tc
Tue, Mar-22-05, 17:16
http://www.reuters.com/newsArticle.jhtml?type=3DhealthNews&st-
oryID=3D7964727
Limiting Carbs Results in Greater Weight Loss Mon Mar 21, 2005
06:45 PM ET
NEW YORK (Reuters Health) - Obese women who follow
low-carbohydrate diets, such as the Atkins diet, may lose more
weight in a four-month period than those who go on low-fat
diets, new study findings show. The reason for the greater
weight loss, however, is not clear. "The differential weight
loss is not explained by differences in resting energy
expenditure, thermic effect of food or physical activity,"
write study author Dr. Bonnie J. Brehm, of the University of
Cincinnati, Ohio and her team.
In a previously published study, Brehm and her colleagues
compared the effects of a low-carbohydrate diet versus a
low-fat diet among obese women. They found that the women on
the low-carbohydrate diet lost more than twice as much
weight as those in the comparison group during a six-month
study period.
The researchers hypothesized that the greater weight loss
among those on the low-carbohydrate diet was due to the
women's greater energy expenditure. "If it's not calories in,
it must be calories out," Brehm told Reuters Health.
Some advocates of low-carbohydrate diets say that such diets
promote increased energy expenditure, but this claim has not
been formally tested, until now.
To investigate, Brehm and her team randomly assigned 50
moderately obese women to a low-carbohydrate diet group
or a low-fat diet group. Only the low-fat group was told
to restrict their caloric intake. Forty women completed
the study.
By the end of the four-month study, women in both groups had
lost weight and body fat, the researchers report in this
month's issue of the Journal of Clinical Endocrinology and
Metabolism. However, the low-carbohydrate group lost more than
10 percent of their body weight, while the low-fat group lost
about 7 percent.
Specifically, the low-carbohydrate group lost 9.8 kilograms
(21.6 pounds) of weight and 6.2 kilograms (13.7 pounds) of
body fat, while the low-fat group lost about 6.1 kilograms (13
pounds) of weight and 3=2E2 kilograms (7 pounds) of body fat,
the report indicates.
To estimate their level of physical activity, women in both
groups were fitted with pedometers, which recorded the number
of steps they took daily. At the start of the study, both
groups of women had similar pedometer readings, and by the end
of the study, there were no significant changes, according to
Brehm and her team.
Resting energy expenditure was also similar between the two
groups at the start of the study and remained comparable four
months later.
The thermic effect of food (TEF), which comprises up to 10
percent of the amount of energy consumed daily, includes the
energy expended during digestion. When the investigators
obtained TEF measurements after the women ate breakfasts
containing a similar number of calories, they found that
those on the low-fat diet expended more energy in a
five-hour period.
This suggests that the low-fat meal was absorbed more quickly
than the low-carbohydrate meal, the report indicates. Yet,
even if the TEF of the low-carbohydrate meal had been
underestimated, the researchers "would not have approached the
amount of energy needed to account for the greater weight loss
in this group," they write.
"These results confirm that short-term weight loss is greater
in obese women on a low-carbohydrate diet than in those on a
low-fat diet even when reported food intake is similar,"
according to Brehm and her team.
SOURCE: Journal of Clinical Endocrinology and Metabolism,
March 2005
***********
The Role of Energy Expenditure in the Differential Weight Loss
in Obese Women on Low-Fat and Low-Carbohydrate Diets Bonnie J.
Brehm, Suzanne E. Spang, Barbara L. Lattin, Randy J. Seeley,
Stephen R. Daniels and David A. D'Alessio University of
Cincinnati (B.J.B., S.E.S., B.L.L., R.J.S., D.A.D.) and
Cincinnati Children's Hospital Medical Center (S.R.D.),
Cincinnati, Ohio 45221
Address all correspondence and requests for reprints to:
Bonnie Brehm, Ph.D., R.D., University of Cincinnati, P.O. Box
210038, Cincinnati, Ohio 45221-0038. E-mail:
bonnie.brehm@uc.edu.
We have recently reported that obese women randomized to a
low-carbohydrate diet lost more than twice as much weight as
those following a low-fat diet over 6 months. The difference
in weight loss was not explained by differences in energy
intake because women on the two diets reported similar daily
energy consumption. We hypothesized that chronic ingestion of
a low-carbohydrate diet increases energy expenditure relative
to a low-fat diet and that this accounts for the differential
weight loss. To study this question, 50 healthy, moderately
obese (body mass index, 33.2 =B1 0.28 kg/m2) women were
randomized to 4 months of an ad libitum low-carbohydrate diet
or an energy-restricted, low-fat diet. Resting energy
expenditure (REE) was measured by indirect calorimetry at
baseline, 2 months, and 4 months. Physical activity was
estimated by pedometers. The thermic effect of food (TEF) in
response to low-fat and low-carbohydrate breakfasts was
assessed over 5 h in a subset of subjects. Forty women
completed the trial. The low-carbohydrate group lost more
weight (9.79 =B1 0.71 vs. 6=2E14 =B1 0.91 kg; P < 0.05) and
more body fat (6.20 =B1 0.67 vs. 3.23 =B1 =2E67 kg; P < 0.05)
than the low-fat group. There were no differences in energy
intake between the diet groups as reported on 3-d food records
at the conclusion of the study (1422 =B1 73 vs. 1530 =B1 102
kcal; 5954 =B1 306 vs. 6406 =B1 427 kJ). Mean REE in the two
groups was comparable at baseline, decreased with weight loss,
and did not differ at 2 or 4 months. The low-fat meal caused a
greater 5-h increase in TEF than did the low-carbohydrate meal
(53 =B1 9 vs. 31 =B1 5 kcal; 222 =B1 38 vs. 130 =B1 21 kJ; P
=3D 0.017). Estimates of physical activity were stable in the
dieters during the study and did not differ between groups.
These results confirm that short-term weight loss is greater
in obese women on a low-carbohydrate diet than in those on a
low-fat diet even when reported food intake is similar. The
differential weight loss is not explained by differences in
REE, TEF, or physical activity and likely reflects
underreporting of food consumption by the low-fat dieters.
*********
TC
oryID=3D7964727
Limiting Carbs Results in Greater Weight Loss Mon Mar 21, 2005
06:45 PM ET
NEW YORK (Reuters Health) - Obese women who follow
low-carbohydrate diets, such as the Atkins diet, may lose more
weight in a four-month period than those who go on low-fat
diets, new study findings show. The reason for the greater
weight loss, however, is not clear. "The differential weight
loss is not explained by differences in resting energy
expenditure, thermic effect of food or physical activity,"
write study author Dr. Bonnie J. Brehm, of the University of
Cincinnati, Ohio and her team.
In a previously published study, Brehm and her colleagues
compared the effects of a low-carbohydrate diet versus a
low-fat diet among obese women. They found that the women on
the low-carbohydrate diet lost more than twice as much
weight as those in the comparison group during a six-month
study period.
The researchers hypothesized that the greater weight loss
among those on the low-carbohydrate diet was due to the
women's greater energy expenditure. "If it's not calories in,
it must be calories out," Brehm told Reuters Health.
Some advocates of low-carbohydrate diets say that such diets
promote increased energy expenditure, but this claim has not
been formally tested, until now.
To investigate, Brehm and her team randomly assigned 50
moderately obese women to a low-carbohydrate diet group
or a low-fat diet group. Only the low-fat group was told
to restrict their caloric intake. Forty women completed
the study.
By the end of the four-month study, women in both groups had
lost weight and body fat, the researchers report in this
month's issue of the Journal of Clinical Endocrinology and
Metabolism. However, the low-carbohydrate group lost more than
10 percent of their body weight, while the low-fat group lost
about 7 percent.
Specifically, the low-carbohydrate group lost 9.8 kilograms
(21.6 pounds) of weight and 6.2 kilograms (13.7 pounds) of
body fat, while the low-fat group lost about 6.1 kilograms (13
pounds) of weight and 3=2E2 kilograms (7 pounds) of body fat,
the report indicates.
To estimate their level of physical activity, women in both
groups were fitted with pedometers, which recorded the number
of steps they took daily. At the start of the study, both
groups of women had similar pedometer readings, and by the end
of the study, there were no significant changes, according to
Brehm and her team.
Resting energy expenditure was also similar between the two
groups at the start of the study and remained comparable four
months later.
The thermic effect of food (TEF), which comprises up to 10
percent of the amount of energy consumed daily, includes the
energy expended during digestion. When the investigators
obtained TEF measurements after the women ate breakfasts
containing a similar number of calories, they found that
those on the low-fat diet expended more energy in a
five-hour period.
This suggests that the low-fat meal was absorbed more quickly
than the low-carbohydrate meal, the report indicates. Yet,
even if the TEF of the low-carbohydrate meal had been
underestimated, the researchers "would not have approached the
amount of energy needed to account for the greater weight loss
in this group," they write.
"These results confirm that short-term weight loss is greater
in obese women on a low-carbohydrate diet than in those on a
low-fat diet even when reported food intake is similar,"
according to Brehm and her team.
SOURCE: Journal of Clinical Endocrinology and Metabolism,
March 2005
***********
The Role of Energy Expenditure in the Differential Weight Loss
in Obese Women on Low-Fat and Low-Carbohydrate Diets Bonnie J.
Brehm, Suzanne E. Spang, Barbara L. Lattin, Randy J. Seeley,
Stephen R. Daniels and David A. D'Alessio University of
Cincinnati (B.J.B., S.E.S., B.L.L., R.J.S., D.A.D.) and
Cincinnati Children's Hospital Medical Center (S.R.D.),
Cincinnati, Ohio 45221
Address all correspondence and requests for reprints to:
Bonnie Brehm, Ph.D., R.D., University of Cincinnati, P.O. Box
210038, Cincinnati, Ohio 45221-0038. E-mail:
bonnie.brehm@uc.edu.
We have recently reported that obese women randomized to a
low-carbohydrate diet lost more than twice as much weight as
those following a low-fat diet over 6 months. The difference
in weight loss was not explained by differences in energy
intake because women on the two diets reported similar daily
energy consumption. We hypothesized that chronic ingestion of
a low-carbohydrate diet increases energy expenditure relative
to a low-fat diet and that this accounts for the differential
weight loss. To study this question, 50 healthy, moderately
obese (body mass index, 33.2 =B1 0.28 kg/m2) women were
randomized to 4 months of an ad libitum low-carbohydrate diet
or an energy-restricted, low-fat diet. Resting energy
expenditure (REE) was measured by indirect calorimetry at
baseline, 2 months, and 4 months. Physical activity was
estimated by pedometers. The thermic effect of food (TEF) in
response to low-fat and low-carbohydrate breakfasts was
assessed over 5 h in a subset of subjects. Forty women
completed the trial. The low-carbohydrate group lost more
weight (9.79 =B1 0.71 vs. 6=2E14 =B1 0.91 kg; P < 0.05) and
more body fat (6.20 =B1 0.67 vs. 3.23 =B1 =2E67 kg; P < 0.05)
than the low-fat group. There were no differences in energy
intake between the diet groups as reported on 3-d food records
at the conclusion of the study (1422 =B1 73 vs. 1530 =B1 102
kcal; 5954 =B1 306 vs. 6406 =B1 427 kJ). Mean REE in the two
groups was comparable at baseline, decreased with weight loss,
and did not differ at 2 or 4 months. The low-fat meal caused a
greater 5-h increase in TEF than did the low-carbohydrate meal
(53 =B1 9 vs. 31 =B1 5 kcal; 222 =B1 38 vs. 130 =B1 21 kJ; P
=3D 0.017). Estimates of physical activity were stable in the
dieters during the study and did not differ between groups.
These results confirm that short-term weight loss is greater
in obese women on a low-carbohydrate diet than in those on a
low-fat diet even when reported food intake is similar. The
differential weight loss is not explained by differences in
REE, TEF, or physical activity and likely reflects
underreporting of food consumption by the low-fat dieters.
*********
TC