>             More Evidence Supports Low-Carbohydrate Diet  CME
>
>             News Author: Laurie Barclay, MD
>             CME Author: Charles Vega, MD, FAAFP

>             >>             May 17, 2004 - Two randomized trials reported
in the May 18
> issue of the Annals of Internal Medicine further support the efficacy of a
> low-carbohydrate diet. A six-month trial showed higher participation and
> greater weight loss, and a 12-month study showed similar weight loss but
> better lipid profile than with a conventional diet. The editorialist uses
> findings from both studies to advise physicians and patients.
>
>             "This diet can be quite powerful. We found that the low-carb
> diet was more effective for weight loss," lead author Will Yancy, MD, from
> Duke University Medical Center and the Veterans Affairs Medical Center in
> Durham, North Carolina, says in a news release. "We also found cholesterol
> levels seemed to improve more on a low-carb diet compared to a low-fat
> diet."
>
>             In this study, which is the first randomized controlled trial
of
> an Atkins-style diet, 120 study participants were assigned to a
> low-carbohydrate, high-protein diet or a low-fat, low-cholesterol,
> low-calorie diet.
>
>             The low-carbohydrate group (<20 g/day) was allowed daily
> unlimited calories, animal foods (meat, fowl, fish, and shellfish), and
> eggs, as well as 4 oz of hard cheese, two cups of salad vegetables
(lettuce,
> spinach, or celery) and one cup of low-carbohydrate vegetables (broccoli,
> cauliflower, or squash). They also received daily nutritional supplements
> including a multivitamin, essential oils, an Atkins diet formulation, and
> chromium picolinate.
>
>             The low-fat, low-cholesterol, low-calorie group received less
> than 30% of daily caloric intake from fat, less than 10% of calories from
> saturated fat, and less than 300 mg cholesterol daily. They were advised
to
> restrict daily calories by 500 to 1,000 calories less than their
maintenance
> diet.
>
>             At study entry, all subjects were between 18 and 65 years of
age
> and in generally good health, with a body mass index (BMI) between 30 and
> 60, and a total cholesterol level greater than 200 mg/dL. None had dieted
or
> used weight loss medications in the previous six months. All subjects were
> encouraged to exercise 30 minutes at least three times per week and had
> regular group meetings at an outpatient research clinic for six months.
>
>             The study was completed by 76% of participants in the
> low-carbohydrate diet group and by 57% of participants in the low-fat diet
> group (P = .02). At six months, weight loss was -12.9% in the
> low-carbohydrate diet group and -6.7% in the low-fat diet group (P <
.001).
>
>             In both groups, loss of fat mass (change, -9.4 kg with the
> low-carbohydrate diet vs. -4.8 kg with the low-fat diet) was greater than
> loss of fat-free mass (change, -3.3 kg vs. -2.4 kg, respectively).
Compared
> with the low-fat diet group, the low-carbohydrate diet group had greater
> decreases in serum triglyceride levels (change, -0.84 mmol/L vs. -0.31
> mmol/L [-74.2 mg/dL vs. -27.9 mg/dL]; P = .004) and greater increases in
> high-density lipoprotein [HDL] cholesterol levels (0.14 mmol/L vs. -0.04
> mmol/L [5.5 mg/dL vs. -1.6 mg/dL]; P < .001).
>
>             Changes in low-density lipoprotein (LDL) cholesterol level
were
> not significantly different between groups (0.04 mmol/L [1.6 mg/dL] with
the
> low-carbohydrate diet and -0.19 mmol/L [-7.4 mg/dL with the low-fat diet;
P
> = .2). However, participants in the low-carbohydrate diet group had more
> minor adverse effects, such as constipation and headaches, than did
patients
> in the low-fat diet group.
>
>             Study limitations include inability to distinguish effects of
> the low-carbohydrate diet and those of the nutritional supplements
provided
> only to that group, and use of healthy participants followed for only 24
> weeks, limiting generalizability of the study results.
>
>             The authors are currently testing whether a low-carbohydrate
> diet can improve glycemic control in diabetes. However, they warn that
> patients with medical conditions such as diabetes and hypertension or who
> use diuretics should not begin a low-carbohydrate diet without close
medical
> supervision, because the diet affects hydration and blood glucose levels.
> Nor do they recommend an Atkins-type diet for individuals attempting to
lose
> weight for the first time.
>
>             "Over six months the diet appears relatively safe, but we need
> to study the safety for longer durations," Dr. Yancy says, noting
potential
> long-term health risks including elevations in LDL cholesterol, bone loss,
> or kidney stones.
>
>             The Robert C. Atkins Foundation funded this research. The
study
> authors have no financial interest in Atkins Nutritionals, Inc.
>
>             In the second study, by Linda Stern, MD, from the Philadelphia
> Veterans Affairs Medical Center in Pennsylvania, and colleagues, 132 obese
> adults were randomized to receive counseling to either restrict
carbohydrate
> intake to less than 30 g per day (low-carbohydrate diet) or to restrict
> caloric intake by 500 calories per day with less than 30% of calories from
> fat (conventional diet). At baseline, BMI was at least 35 kg/m2, and 83%
of
> participants had diabetes or metabolic syndrome.
>
>             By one year, mean weight change was -5.1 ± 8.7 kg in the
> low-carbohydrate diet group and -3.1 ± 8.4 kg in the conventional diet
group
> (difference, -1.9 kg; 95% confidence interval [CI], -4.9 to 1.0 kg; P =
> .20). The low-carbohydrate diet group fared better in terms of greater
> decrease in triglyceride levels (P = .044) and less decrease in HDL
> cholesterol levels (P = .025).
>
>             In the subgroup of 54 persons with diabetes, hemoglobin A1c
> levels improved more with the low-carbohydrate diet, but the difference
was
> not statistically significant in sensitivity analyses. Both groups had
> similar changes in other lipids and in insulin sensitivity.
>
>             Study limitations include high dropout rate of 34% and
> suboptimal dietary adherence.
>
>             "Despite modest overall weight loss in both diet groups,
> assignment to the low-carbohydrate group had a direct and more favorable
> effect on triglyceride level, HDL cholesterol level, and glycemic control
in
> the smaller subgroup of patients with diabetes," the authors write. "These
> findings give further evidence that restriction of carbohydrates in obese
> persons, who may be overconsuming carbohydrates at baseline, may have
> favorable metabolic effects. Caution is still needed, however, in
> recommending a low-carbohydrate diet, as important concerns remain."
>
>             The Veterans Affairs Healthcare Network supported this study.
> The authors report no potential financial conflicts of interest.
>
>             "We can no longer dismiss very-low-carbohydrate diets," Walter
> C. Willett, MD, DrPH, from the Harvard School of Public Health in Boston,
> Massachusetts, writes in an accompanying editorial.
>
>             "We can encourage overweight patients to experiment with
various
> methods for weight control, including reduced-carbohydrate diets, as long
as
> they emphasize healthy sources of fat and protein and incorporate regular
> physical activity," he concludes. "Patients should focus on finding ways
to
> eat that they can maintain indefinitely rather than seeking diets that
> promote rapid weight loss. For many patients, the roll will have little
> role."
...... for the rest see http://www.medscape.com/viewarticle/477732?src=mp

jean-claude