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Weight and Metabolic Outcomes After 2 Years on a Low-Carbohydrate Versus Low-Fat Diet: A Randomized Trial

Gary D. Foster, PhD; Holly R. Wyatt, MD; James O. Hill, PhD; Angela P. Makris, PhD, RD; Diane L. Rosenbaum, BA; Carrie Brill, BS; Richard I. Stein, PhD; B. Selma Mohammed, MD, PhD; Bernard Miller, MD; Daniel J. Rader, MD; Babette Zemel, PhD; Thomas A. Wadden, PhD; Thomas Tenhave, PhD; Craig W. Newcomb, MS; and Samuel Klein, MD
[+] Article and Author Information

From Temple University, University of Pennsylvania School of Medicine, and Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; University of Colorado Denver, Denver, Colorado; and Washington University School of Medicine and University of Missouri, St. Louis, Missouri.


Note: Dr. Foster had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Acknowledgment: The authors thank Brooke Bailer, Eva Greenberg, Eileen Ford, Joan Heins, Jennifer Lundgren, Jennifer McCrea, Donna Paulhamus, Gary Skolnick, Emily Smith, Philippe Szapary, Adam Tsai, and Leslie Womble and for their assistance in conducting this study and the study participants for their participation.

Grant Support: By the National Institutes of Health (NIH) grant R01 AT1103 to Temple University; NIH grant UL1RR024134 to University of Pennsylvania; NIH grant UL1 RR000051 to University of Colorado; and NIH grant UL1 RR024992 and DK 56341 to Washington University.

Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M09-1901.

Reproducible Research Statement:Study protocol: Available from Dr. Foster (e-mail, gfoster@temple.edu). Statistical code: Available from Dr. Tenhave (e-mail, ttenhave@upenn.edu). Data set: Available from Dr. Foster (e-mail, gfoster@temple.edu), subject to study group approval and National Institutes of Health policy.

Requests for Single Reprints: Gary D. Foster, PhD, Center for Obesity Research and Education, Temple University, 3223 North Broad Street, Suite 175, Philadelphia, PA 19140; e-mail, gfoster@temple.edu.

Current Author Addresses: Dr. Foster: Center for Obesity Research and Education, Temple University, 3223 North Broad Street, Suite 175, Philadelphia, PA 19140.

Drs. Wyatt and Hill and Ms. Brill: Center for Human Nutrition, University of Colorado Denver, University North Pavilion Building, 4455 East 12th Avenue, 300Z, Denver, CO 80220.

Dr. Makris: 45 Morning Glory Way, Huntingdon Valley, PA 19006.

Ms. Rosenbaum: Department of Psychology, Washington University School of Medicine, 212 Stadler Hall, St. Louis, MO 63121.

Drs. Stein, Mohammed, and Miller: Division of Geriatrics and Nutritional Science, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110.

Dr. Rader: Institute for Translational Medicine and Therapeutics, Room 654, Biomedical Research Building II/III, 421 Curie Boulevard, Philadelphia, PA 19104-6160.

Dr. Zemel: Division of Gastroenterology, Hepatology, and Nutrition, The Children's Hospital of Philadelphia, 3535 Market Street, Room 1560, Philadelphia, PA 19104-4399.

Dr. Wadden: Center for Weight and Eating Disorders, 3535 Market Street, Suite 3029, Philadelphia, PA 19104.

Dr. Tenhave and Mr. Newcomb: Center for Clinical Epidemiology and Biostatistics, Department of Biostatistics and Epidemiology, 8th Floor, Blockley Hall, University of Pennsylvania School of Medicine, 423 Guardian Drive, Philadelphia, PA 19104-6021.

Dr. Klein: Center for Human Nutrition, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110.

Author Contributions: Conception and design: G.D. Foster, H.R. Wyatt, J.O. Hill, A.P. Makris, C. Brill, D.J. Rader, T.A. Wadden, S. Klein.

Analysis and interpretation of the data: G.D. Foster, H.R. Wyatt, J.O. Hill, D.J. Rader, B. Zemel, T. Tenhave, C.W. Newcomb, S. Klein.

Drafting of the article: G.D. Foster, H.R. Wyatt, J.O. Hill, B. Zemel, T. Tenhave, S. Klein.

Critical revision of the article for important intellectual content: G.D. Foster, H.R. Wyatt, J.O. Hill, A.P. Makris, D.L. Rosenbaum, R.I. Stein, B.S. Mohammed, B. Miller, D.J. Rader, T.A. Wadden, S. Klein.

Final approval of the article: G.D. Foster, H.R. Wyatt, J.O. Hill, C. Brill, R.I. Stein, B.S. Mohammed, B. Miller, D.J. Rader, T.A. Wadden, T. Tenhave, C.W. Newcomb, S. Klein.

Provision of study materials or patients: G.D. Foster, H.R. Wyatt, J.O. Hill, B.S. Mohammed, B. Miller, T.A. Wadden.

Statistical expertise: T. Tenhave, C.W. Newcomb.

Obtaining of funding: G.D. Foster, H.R. Wyatt, J.O. Hill, T. Tenhave, S. Klein.

Administrative, technical, or logistic support: G.D. Foster, J.O. Hill, D.L. Rosenbaum, C. Brill, R.I. Stein, B.S. Mohammed, B. Miller, B. Zemel, T. Tenhave, S. Klein.

Collection and assembly of data: G.D. Foster, H.R. Wyatt, J.O. Hill, A.P. Makris, D.L. Rosenbaum, C. Brill, R.I. Stein, B.S. Mohammed, B. Miller, D.J. Rader, B. Zemel, T.A. Wadden, S. Klein.


Ann Intern Med. 2010;153(3):147-157. doi:10.7326/0003-4819-153-3-201008030-00005
Text Size: A A A

This article has been corrected. For original version, click “Original Version (PDF)” in column 2.

Background: Previous studies comparing low-carbohydrate and low-fat diets have not included a comprehensive behavioral treatment, resulting in suboptimal weight loss.

Objective: To evaluate the effects of 2-year treatment with a low-carbohydrate or low-fat diet, each of which was combined with a comprehensive lifestyle modification program.

Design: Randomized parallel-group trial. (ClinicalTrials.gov registration number: NCT00143936)

Setting: 3 academic medical centers.

Patients: 307 participants with a mean age of 45.5 years (SD, 9.7 years) and mean body mass index of 36.1 kg/m2 (SD, 3.5 kg/m2).

Intervention: A low-carbohydrate diet, which consisted of limited carbohydrate intake (20 g/d for 3 months) in the form of low–glycemic index vegetables with unrestricted consumption of fat and protein. After 3 months, participants in the low-carbohydrate diet group increased their carbohydrate intake (5 g/d per wk) until a stable and desired weight was achieved. A low-fat diet consisted of limited energy intake (1200 to 1800 kcal/d; ≤30% calories from fat). Both diets were combined with comprehensive behavioral treatment.

Measurements: Weight at 2 years was the primary outcome. Secondary measures included weight at 3, 6, and 12 months and serum lipid concentrations, blood pressure, urinary ketones, symptoms, bone mineral density, and body composition throughout the study.

Results: Weight loss was approximately 11 kg (11%) at 1 year and 7 kg (7%) at 2 years. There were no differences in weight, body composition, or bone mineral density between the groups at any time point. During the first 6 months, the low-carbohydrate diet group had greater reductions in diastolic blood pressure, triglyceride levels, and very-low-density lipoprotein cholesterol levels, lesser reductions in low-density lipoprotein cholesterol levels, and more adverse symptoms than did the low-fat diet group. The low-carbohydrate diet group had greater increases in high-density lipoprotein cholesterol levels at all time points, approximating a 23% increase at 2 years.

Limitation: Intensive behavioral treatment was provided, patients with dyslipidemia and diabetes were excluded, and attrition at 2 years was high.

Conclusion: Successful weight loss can be achieved with either a low-fat or low-carbohydrate diet when coupled with behavioral treatment. A low-carbohydrate diet is associated with favorable changes in cardiovascular disease risk factors at 2 years.

Primary Funding Source: National Institutes of Health.

Figures

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Figure 1.
Study flow diagram.

“In treatment” refers to the participants who were still in treatment but did not complete the assessment. “Discontinued treatment” refers to the participants who formally withdrew from the study or could not be contacted (that is, lost to follow-up).

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Figure 2.
Predicted absolute mean change in body weight for participants in the low-fat and low-carbohydrate diet groups, based on a random-effects linear model.

Error bars represent 95% CIs.

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Figure 3.
Predicted absolute mean change in serum triglyceride, VLDL cholesterol, LDL cholesterol, and HDL cholesterol concentrations in the low-fat and low-carbohydrate diet groups, based on a random-effects linear model.

Error bars represent 95% CIs. To convert triglycerides to mmol/L, multiply by 0.0113. To convert HDL, LDL, and VLDL cholesterol to mmol/L, multiply by 0.0259. HDL= high-density lipoprotein cholesterol; LDL= low-density lipoprotein cholesterol; VLDL = very-low-density lipoprotein cholesterol.

* P < 0.001.

P < 0.01 for between-group differences.

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A comment on "Weight and Metabolic Outcomes After 2 Years on a Low-Carbohydrate Versus Low-Fat Diet: A Randomized Trial"
Posted on August 11, 2010
Saurabh Sethi
Wayne State University, Detroit, MI
Conflict of Interest: None Declared

In their article (August 3 issue) (1), the authors report that a successful weight loss can be achieved with either a low-fat or low- carbohydrate diet when coupled with behavioral treatment.

This was a randomized control trial looking at the effects of 2-year treatment with a low-carbohydrate or low-fat diet, each of which was combined with a comprehensive lifestyle modification program. This is a well done study with a good job in randomization and study design. This study build upon the results of an earlier study published in NEJM (2) comparing the weight loss with low carbohydrate and low fat diets at the end of 2 years (this is the only 2 year randomized controlled trial that has been published before the current study). Even though the two studies differed in study setting, patient samples etc., we can still draw some comparisons. The NEJM study found greater 2-year weight loss with a low carbohydrate diet than low fat diet, unlike the current study. The study reported mean weight losses of 5.5 kg and 3.3 kg among low carbohydrate diet and low fat diet respectively. However, the current study reports approximately 7 kg weight loss among both the groups. The authors mention that even though low fat diet traditionally has associated adherence problems, the difference in adherence may be overcome by comprehensive behavioral treatment.

However, the authors have failed to comment upon one very important variable. What was the level of physical activity at baseline among both groups and what was the change at 3, 6, 12 and 24 months? Without this information, it is very difficult to draw concrete conclusions from the current study.

Another issue that needs clarification is whether the two groups were similar in terms of hormonal replacement therapy (HRT). The authors mention: we excluded study applicants if they...took medications that affect body weight, including antiobesity agents. Did the list of medications include HRT, since HRT affects lipid profile (3). This issue is all the more important since two-thirds of the study sample consisted of females!

The same concern I have is for smoking status among both the groups, since smoking can affect lipoprotein concentrations (4). The authors have not reported smoking status among the two groups.

Overall, the findings of the study are quite interesting but in the light of the above facts, readers need to apply caution.

References

1.Foster GD, Wyatt HR, Hill JO, et. al. Weight and metabolic outcomes after 2 years on a low-carbohydrate versus low-fat diet: a randomized trial. Ann Intern Med. 2010 Aug 3;153(3):147-57.

2.Shai I, Schwarzfuchs D, Henkin Y, et. al. Weight loss with a low- carbohydrate, Mediterranean, or low-fat diet. N Engl J Med. 2008 Jul 17;359(3):229-41.

3.Walsh BW, Schiff I, Rosner B, et. al. Effects of postmenopausal estrogen replacement on the concentrations and metabolism of plasma lipoproteins. N Engl J Med 1991 Oct 24;325(17):1196-204.

4.Freeman DJ, Griffin BA, Murray E, et al. Smoking and plasma lipoproteins in man: Effects on low density lipoprotein cholesterol levels and high density lipoprotein subfraction distribution. Eur J Clin Invest 1993 Oct;23(10):630-40.

Conflict of Interest:

None declared

Important to measure coronary heart disease, not just risk factors
Posted on September 1, 2010
Dean Ornish
Clinical Professor of Medicine, University of California, San Francisco
Conflict of Interest: None Declared

To the Editor:

The authors concluded, "Successful weight loss can be achieved with either a low-fat or low-carbohydrate diet when coupled with behavioral treatment. A low-carbohydrate diet is associated with favorable changes in cardiovascular disease risk factors at 2 years."

It is important to measure coronary heart disease, not just risk factors, which can be misleading. A recent study found that an Atkins- type diet "promotes atherosclerosis through mechanisms that do not modify the classic cardiovascular risk factors" such as HDL" (1).

Other studies also showed that measures of heart disease, not just risk factors, worsened on an Atkins diet, including myocardial perfusion, flow-mediated vasodilation, and inflammation but improved significantly on a low-fat, whole foods, plant-based diet (2,3).

No published study has ever shown that an Atkins diet prevents or reverses the progression of coronary heart disease. In contrast, a whole foods plant-based diet much lower in fat than used in this study (10% vs. 30% fat) can reverse coronary heart disease,(4) beneficially affect the progression of prostate cancer, and even improve gene expression and telomerase despite reductions in HDL. It would be unfortunate if people are discouraged from making these diet and lifestyle changes because they incorrectly believe that an Atkins-type diet can provide comparable benefits (5).

The authors reported an overall significant decrease in LDL in the low-fat diet and a rise in HDL in the Atkins diet. Other risk factors were not significantly different. LDL is strongly linked with coronary heart disease, but not everything that raises HDL is beneficial.

HDL is part of reverse cholesterol transport. When you eat more saturated fat and dietary cholesterol, your body makes more HDL to remove it. Eating a stick of butter will raise HDL, but butter is not heart- healthy. Pfizer discontinued a study of its drug, torcetrapib, which raised HDL but actually increased risk of cardiac events. A low HDL in the context of a healthy low-fat diet has a very different prognostic significance than a low HDL in someone eating a high-fat, high-cholesterol diet.

It's not low-fat vs. low-carb. Atkins- type diets may have some benefits because the typical American diet, and many low-fat diets, are very high in refined carbohydrates. Even better is to consume a diet that is low in refined carbohydrates as well as low in saturated fat, trans fats, and animal protein, includes beneficial fats such as omega-3 fatty acids, and high in fruits and vegetables in their natural, unrefined forms.

References

1. Smith SR. A look at the low-carbohydrate diet. N Engl J Med. 2009;361:23,

2. Miller M, Beach V, Sorkin JD, et al. Comparative effects of three popular diets on lipids, endothelial function, and C-reactive protein during weight maintenance. J Am Diet Assoc. 2009;109:713-717.

3. Fleming R, Boyd LB. The effect of high-protein diets on coronary blood flow. Angiology. 2000;51:817-826.

4. Ornish D, Scherwitz L, Billings J, Brown SE, Gould KL, Merritt TA, Sparler S, Armstrong WT, Ports TA, Kirkeeide RL, Hogeboom C, Brand RJ. Intensive lifestyle changes for reversal of coronary heart disease Five- year follow-up of the Lifestyle Heart Trial. JAMA. 1998;280:2001-2007.

5. Ornish D. Was Dr. Atkins right? Journal of the American Dietetic Association. 2004;104(4):537-542.

Conflict of Interest:

Disclosure: I write general-interest books on health for which I receive royalties, receive lecture honoraria, and consult for Mars, Inc. to make healthier foods.

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Summary for Patients

Comparison of Weight Loss at 2 Years on a Low-Carbohydrate Versus Low-Fat Diet

The summary below is from the full report titled “Weight and Metabolic Outcomes After 2 Years on a Low-Carbohydrate Versus Low-Fat Diet. A Randomized Trial.” It is in the 3 August 2010 issue of Annals of Internal Medicine (volume 153, pages 147-157). The authors are G.D. Foster, H.R. Wyatt, J.O. Hill, A.P. Makris, D.L. Rosenbaum, C. Brill, R.I. Stein, B.S. Mohammed, B. Miller, D.J. Rader, B. Zemel, T.A. Wadden, T. Tenhave, C.W. Newcomb, and S. Klein.

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