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2. Baker LC. Association of managed care market share and health expenditures for fee-for-service Medicare patients. JAMA. 1999;281(5):432-437. 3. Chernew M, Decicca P, Town R. Managed care and medical expenditures of Medicare beneficiaries. J Health Econ. 2008;27(6):1451-1461. 4. Song Z, Safran DG, Landon BE, et al. The ‘Alternative Quality Contract,’ based on a global budget, lowered medical spending and improved quality. Health Aff (Millwood). 2012;31(8):1885-1894.

Adherence to Diets for Weight Loss To the Editor: In a recent Viewpoint, Drs Pagoto and Appelhans1 made a convincing argument for researching new strategies to improve adherence to lifestyle modifications intended for weight management. We disagree, however, that further study of diets with varying macronutrient composition is no longer helpful. Controversy remains regarding the safety of these diets and their effectiveness for improving health outcomes.2 The various diets that are commonly studied (eg, low-fat, Mediterranean, low-carbohydrate, low-glycemic index, vegetarian) can have widely different metabolic and health effects, particularly when adherence is high and even if weight loss is ultimately similar.3 More importantly, despite voluminous research on diet and health, there is scant high-quality evidence (ie, randomized controlled trials) to support any diet’s beneficial effects on clinical events. Until questions about safety and effectiveness are settled, it may be difficult to convince practitioners to “counsel patients to choose a dietary plan they find easiest to adhere to in the long term.”1 Furthermore, whereas selection of a diet based on an individual’s preference is compelling, it is unclear that this approach will produce maximal weight loss or health benefits; one study found inferior weight loss when patients were assigned to a preferred weight loss diet.4 Controversy also remains regarding how adherable these different diets are, meaning that any research done on adherence to one particular diet may not be generalizable to other approaches. There is no doubt that depictions of research on various diets, both accurate and inaccurate, have led to confusion among patients, clinicians, and experts alike. However, a lack of scientific research on a diet approach is unlikely to reduce confusion or stem the popularity of new dietary approaches, which can become a focus of popular media attention and commercialization regardless of the existence of research. Ignoring approaches that may have different appeal, adherence, and metabolic effects will diminish continued progress toward increased treatment options, targeted therapy, and personalized nutrition. Considering only one diet approach in research can lead to overlooking the shortcomings of that particular approach. In other words, we agree the pursuit of the one ideal diet for everyone should end, but a better understanding of the spectrum of potential ideal diets for every individual should continue to be pursued. William S. Yancy Jr, MD, MHSc Megan A. McVay, PhD Grant D. Brinkworth, PhD 2676

Author Affiliations: Department of Medicine, Duke University Medical Center, Durham, North Carolina (Yancy, McVay); Commonwealth Scientific and Industrial Research Organisation, Adelaide, South Australia, Australia (Brinkworth). Corresponding Author: William S. Yancy Jr, MD, MHSc, VA Medical Center, 508 Fulton St, Durham, NC 27705 ([email protected]). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr McVay reported receiving a grant from the Agency for Healthcare Research and Quality. No other disclosures were reported. 1. Pagoto SL, Appelhans BM. A call for an end to the diet debates. JAMA. 2013;310(7):687-688. 2. Noto H, Goto A, Tsujimoto T, Noda M. Low-carbohydrate diets and all-cause mortality: a systematic review and meta-analysis of observational studies. PLoS One. 2013;8(1):e55030. 3. Nordmann AJ, Nordmann A, Briel M, et al. Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Arch Intern Med. 2006;166(3):285-293. 4. Borradaile KE, Halpern SD, Wyatt HR, et al. Relationship between treatment preference and weight loss in the context of a randomized controlled trial. Obesity (Silver Spring). 2012;20(6):1218-1222.

In Reply Even though they agree with our emphasis on behavioral adherence, Dr Yancy and colleagues advocate for additional diet comparison studies given the controversy regarding their effectiveness for improving health outcomes. Specifically, Yancy and colleagues describe scant highquality evidence to support any diet’s beneficial effects on clinical events. We agree with the importance of demonstrating effects of diet on clinical events (eg, incident diabetes, stroke) rather than on weight and cardiometabolic risk factors alone. However, to the extent that the dietary effects on clinical events are driven by weight loss, the 4 meta-analyses1-4 cited in our Viewpoint, and a fifth published afterward,5 indicate that differences between individual diets are likely to be trivial. Although individual studies sometimes show small to moderate differences between diets on various cardiometabolic risk factors, meta-analyses indicate either negligible or inconsistent effects on fasting glucose and lipid profiles.1-5 Such findings do not support the value of long-term studies (eg, 5-10 years of follow-up) comparing different macronutrientbased diets on clinical events and safety, particularly when behavioral adherence declines greatly during a year.6 The difference in efficacy between any 2 diets is likely explained by macronutrient composition, caloric restriction, and adherence. Unfortunately, research has focused almost exclusively on macronutrients and caloric restriction, which sends a message of false hope to the public that weight management is as simple as striking the perfect macronutrient balance. We are not suggesting total cessation of all diet comparison research, but rather that the perspective be broadened to acknowledge that diet is not merely a biochemical process but instead heavily relies on human behavior. This means prioritizing behavioral adherence as a topic deserving intensive study and as a primary intervention target in lifestyle interventions. In addition, we do not share the sentiment of Yancy and colleagues that scaling back on diet comparison studies will do little to stop the proliferation of fad diets or reduce public confusion. The scientific community has a responsibility to

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guide the national dialogue to a better understanding of the factors that influence weight management. A narrow focus on macronutrient composition is no longer moving the field forward and fuels the counterproductive debate occurring in the media and fad diet industry. Sherry Pagoto, PhD Bradley M. Appelhans, PhD Author Affiliations: Division of Preventive and Behavioral Medicine, University of Massachusetts Medical School, Worcester (Pagoto); Rush University Medical Center, Chicago, Illinois (Appelhans). Corresponding Author: Sherry Pagoto, PhD, University of Massachusetts Medical School, 55 Lake Ave N, Worcester, MA 01655 (sherry.pagoto @umassmed.edu). Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Pagoto reported receiving grants from the National Institutes of Health; and serving on the advisory board of Mobile Wellbeing Inc. Dr Appelhans reported receiving grant funding from Hillshire Brands Company. 1. Bueno NB, de Melo IS, de Oliveira SL, da Rocha Ataide T. Very-lowcarbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials. Br J Nutr. 2013;110(7):1178-1187. 2. Wycherley TP, Moran LJ, Clifton PM, Noakes M, Brinkworth GD. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2012;96(6):1281-1298. 3. Hu T, Mills KT, Yao L, et al. Effects of low-carbohydrate diets versus low-fat diets on metabolic risk factors: a meta-analysis of randomized controlled clinical trials. Am J Epidemiol. 2012;176(suppl 7):S44-S54. 4. Ajala O, English P, Pinkney J. Systematic review and meta-analysis of different dietary approaches to the management of type 2 diabetes. Am J Clin Nutr. 2013;97(3):505-516. 5. Schwingshackl L, Hoffmann G. Long-term effects of low-fat diets either low or high in protein on cardiovascular and metabolic risk factors: a systematic review and meta-analysis. Nutr J. 2013;12:48. 6. Dansinger ML, Gleason JA, Griffith JL, Selker HP, Schaefer EJ. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA. 2005;293(1):43-53.

CORRECTION Correction in Editorial Wording: In the Editorial entitled “Containing Multitudes: Medical Education 2013” published in the December 4, 2013, issue of JAMA (2013;310[21]:2259-2261. doi:10.1001/jama.2013.283429), one paragraph contained incorrect wording. The first sentence of the fifth paragraph should have begun “In a study of internal medicine and nurse practitioner trainees, Curtis and colleagues2 used a randomized trial.…” Halfway down the same paragraph, the word “students” should be replaced with “trainees”: “Although the authors previously reported evidence using standardized patients supporting that these trainees had gained the desired skills for end-of-life communications.…” This article was corrected online.

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