Headline from CNN:
Reports: Low-carb has mixed results Tuesday, May 18, 2004
Posted: 8:55 AM EDT (1255 GMT)
WASHINGTON (Reuters) -- Low-carbohydrate diets help people
lose weight in the short term but work no better than other
diets after a year, researchers reported on Monday.
The actual abstracts, read the conclusions:
*******
A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To
Treat Obesity and Hyperlipidemia
A Randomized, Controlled Trial William S. Yancy, Jr., MD,
MHS; Maren K. Olsen, PhD; John R. Guyton, MD; Ronna P.
Bakst, RD; and Eric C. Westman, MD, MHS
18 May 2004 | Volume 140 Issue 10 | Pages 769-777
Background: Low-carbohydrate diets remain popular despite a
paucity of scientific evidence on their effectiveness.
Objective: To compare the effects of a low-carbohydrate,
ketogenic diet program with those of a low-fat, low-
cholesterol, reduced-calorie diet.
Design: Randomized, controlled trial.
Setting: Outpatient research clinic.
Participants: 120 overweight, hyperlipidemic volunteers from
the community.
Intervention: Low-carbohydrate diet (initially, <20 g of
carbohydrate daily) plus nutritional supplementation,
exercise recommendation, and group meetings, or low-fat diet
(<30% energy from fat, <300 mg of cholesterol daily, and
deficit of 500 to 1000 kcal/d) plus exercise recommendation
and group meetings.
Measurements: Body weight, body composition, fasting serum
lipid levels, and tolerability.
Results: A greater proportion of the low-carbohydrate diet
group than the low-fat diet group completed the study (76%
vs. 57%; P = 0.02). At 24 weeks, weight loss was greater in
the low-carbohydrate diet group than in the low-fat diet
group (mean change, –12.9% vs. –6.7%; P < .001). Patients in
both groups lost substantially more fat mass (change, –9.4
kg with the low-carbohydrate diet vs. –4.8 kg with the low-
fat diet) than fat-free mass (change, –3.3 kg vs. –2.4 kg,
respectively). Compared with recipients of the low-fat diet,
recipients of the low-carbohydrate diet 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 = 0.004) and greater increases in
high-density lipoprotein cholesterol levels (0.14 mmol/L
vs. –0.04 mmol/L [5.5 mg/dL vs. –1.6 mg/dL]; P < 0.001).
Changes in low-density lipoprotein cholesterol level did
not differ statistically (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 = 0.2). Minor adverse effects
were more frequent in the low-carbohydrate diet group.
Limitations: We could not definitively distinguish effects
of the low-carbohydrate diet and those of the nutritional
supplements provided only to that group. In addition,
participants were healthy and were followed for only 24
weeks. These factors limit the generalizability of the
study results.
Conclusions: Compared with a low-fat diet, a low-
carbohydrate diet program had better participant retention
and greater weight loss. During active weight loss, serum
triglyceride levels decreased more and high-density
lipoprotein cholesterol level increased more with the low-
carbohydrate diet than with the low-fat diet.
**************
The Effects of Low-Carbohydrate versus Conventional Weight
Loss Diets in Severely Obese Adults: One-Year Follow-up of a
Randomized Trial Linda Stern, MD; Nayyar Iqbal, MD; Prakash
Seshadri, MD; Kathryn L. Chicano, CRNP; Denise A. Daily, RD;
Joyce McGrory, CRNP; Monica Williams, BS; Edward J. Gracely,
PhD; and Frederick F. Samaha, MD
18 May 2004 | Volume 140 Issue 10 | Pages 778-785
Background: A previous paper reported the 6-month comparison
of weight loss and metabolic changes in obese adults
randomly assigned to either a low-carbohydrate diet or a
conventional weight loss diet.
Objective: To review the 1-year outcomes between these
diets.
Design: Randomized trial.
Setting: Philadelphia Veterans Affairs Medical Center.
Participants: 132 obese adults with a body mass index
of 35 kg/m2 or greater; 83% had diabetes or the
metabolic syndrome.
Intervention: Participants received counseling to either
restrict carbohydrate intake to <30 g per day (low-
carbohydrate diet) or to restrict caloric intake by 500
calories per day with <30% of calories from fat
(conventional diet).
Measurements: Changes in weight, lipid levels, glycemic
control, and insulin sensitivity.
Results: By 1 year, mean (±SD) weight change for persons on
the low-carbohydrate diet was –5.1 ± 8.7 kg compared with
–3.1 ± 8.4 kg for persons on the conventional diet.
Differences between groups were not significant (–1.9 kg
[95% CI, –4.9 to 1.0 kg]; P = 0.20). For persons on the low-
carbohydrate diet, triglyceride levels decreased more (P =
0.044) and high-density lipoprotein cholesterol levels
decreased less (P = 0.025). As seen in the small group of
persons with diabetes (n = 54) and after adjustment for
covariates, hemoglobin A1c levels improved more for persons
on the low-carbohydrate diet. These more favorable
metabolic responses to a low-carbohydrate diet remained
significant after adjustment for weight loss differences.
Changes in other lipids or insulin sensitivity did not
differ between groups.
Limitations: These findings are limited by a high dropout
rate (34%) and by suboptimal dietary adherence of the
enrolled persons.
Conclusion: Participants on a low-carbohydrate diet had more
favorable overall outcomes at 1 year than did those on a
conventional diet. Weight loss was similar between groups,
but effects on atherogenic dyslipidemia and glycemic control
were still more favorable with a low-carbohydrate diet after
adjustment for differences in weight loss.
******
Low-carb outperformed low-fat in both studies, both in
weight loss and in lipid profile improvement and yet the
headline suggests that this was "mixed results". Another
example of studies showing clear results and the purveyors
of the message changing the message entirely.
Now we have scientific evidence that low-carb works and is
healthy over a one year period.
TC