The prevalence of obesity (body mass index [BMI] 30 kg/m2) in US adults has skyrocketed over the past 30 years, affecting approximately 33% in the VA nationally in 2000 and approximately 36% at the Durham VAMC currently. Thus, identifying effective strategies for treating obesity is both a public health and a VA priority. A variety of diet approaches have proven successful in achieving moderate weight loss in many individuals. Most diet interventions fail to achieve meaningful weight loss in more than a few individuals. This failure likely results from inadequate adherence to the diet.
The proposed study will test the commonly proposed assumption that helping patients to choose a diet based on their dietary preferences will increase weight loss success relative to assigning or recommending a single diet. The objectives of this study are to: (a) examine the difference in weight loss at 48 weeks among participants randomized to the Choice arm versus participants randomized to the Control arm; (b) examine the difference in diet adherence at 48 weeks among participants randomized to the Choice arm versus participants randomized to the Control arm; and (c) examine the difference in obesity-specific health-related quality of life (HRQOL) at 48 weeks among participants randomized to the Choice arm versus participants randomized to the Control arm.
The proposed study is a 2-arm randomized controlled trial involving 216 outpatients from Durham VA Medical Center. Participants must be obese (BMI 30 kg/m) VAMC outpatients without unstable health issues. Participants in the experimental arm (Choice) will select either a low-carbohydrate, calorie-unrestricted diet (LCD) or a low-fat, reduced-calorie diet (LFD) after being informed by results from a validated food preference questionnaire and a discussion of available diet options with trained personnel. The Choice participants will also have the opportunity to switch to the other diet after 3 months if unsuccessful or dissatisfied with their primary selection. Participants in the Control arm will be randomly assigned to follow one of the two diets for the duration of follow-up. All participants will receive diet-appropriate counseling in small group meetings every 2 weeks for 24 weeks, then monthly for another 24 weeks. All participants will also receive brief telephone counseling involving individual goal setting and problem solving halfway through each month in the latter 24 weeks.
The primary outcome is weight change from baseline to 48 weeks. Secondary outcomes include adherence to diet by food frequency questionnaire and obesity-specific health-related quality of life. Exploratory analyses will examine whether the impact of choice versus lack of choice on weight loss is moderated by individual differences in the constructs of autonomy orientation, competence, and relatedness.
A total of 207 participants were enrolled. Mean age was 54 (SD=11) years, 27% were women, 51% were White, 43% were Black, 22% had diabetes. Mean weight at baseline was 109 (SD=21) kg and mean BMI 36 (SD=6) kg/m2. Of enrolled participants, 105 randomized to the Choice arm, 102 to the Control arm. In the Choice arm, 61 (58%) chose the low-carbohydrate diet and 44 (42%) chose the low-fat diet. Only three low-carbohydrate and two low-fat diet participants switched diets at 12 weeks. Final measurements were collected in 175 (85%) participants, 87 (83%) in the Choice arm and 88 (86%) in the Control arm. For the primary outcome, mean weight loss at 48 weeks was -4.2% of original weight in the Choice participants and -5.3% in Control participants (difference 1.1, 95% CI 0.0 - 2.2, p=0.06). For the secondary outcome, adherence to diet, preliminary descriptive analyses showed that adherence was quite similar between the Choice and Control arms, with mean percent deviation from goal ranging from 7-10% at the 4 time points (12, 24, 36, 48 weeks) in both arms and differing by only 0.6% (10.7 vs 10.1% deviation, respectively) at week 48. Mean IWQOL-Lite total score was similar in both groups at week 48 (Choice 81.7, Control 82.9, difference -1.3, 95% CI -4.5 - 2.0, p=0.4).
The commonly held notion that we should allow patients to choose a diet approach to follow, because multiple diet approaches are effective for weight loss and choosing would enhance adherence, did not bear true in a randomized trial. Future research should consider targeting diet to patient based on metabolic, genetic or other characteristics that might predict improved outcomes.
- McVay MA, Voils CI, Geiselman PJ, Smith VA, Coffman CJ, Mayer S, Yancy WS. Food preferences and weight change during low-fat and low-carbohydrate diets. Appetite. 2016 Aug 1; 103:336-343.
- Yancy WS, McVay MA, Voils CI. Effect of allowing choice of diet on weight loss--in response. Annals of internal medicine. 2015 Nov 17; 163(10):805-6.
- Yancy WS, Mayer SB, Coffman CJ, Smith VA, Kolotkin RL, Geiselman PJ, McVay MA, Oddone EZ, Voils CI. Effect of Allowing Choice of Diet on Weight Loss: A Randomized Trial. Annals of internal medicine. 2015 Jun 16; 162(12):805-14.
- McVay MA, Jeffreys AS, King HA, Olsen MK, Voils CI, Yancy WS. The relationship between pretreatment dietary composition and weight loss during a randomised trial of different diet approaches. Journal of human nutrition and dietetics : the official journal of the British Dietetic Association. 2015 Feb 1; 28 Suppl 2:16-23.
- McVay MA, Voils CI, Coffman CJ, Geiselman PJ, Kolotkin RL, Mayer SB, Smith VA, Gaillard L, Turner MJ, Yancy WS. Factors associated with choice of a low-fat or low-carbohydrate diet during a behavioral weight loss intervention. Appetite. 2014 Dec 1; 83:117-24.
- McVay MA, Yancy WS, Vijan S, Van Scoyoc L, Neelon B, Voils CI, Maciejewski ML. Obesity-related health status changes and weight-loss treatment utilization. American journal of preventive medicine. 2014 May 1; 46(5):465-72.
- Yancy WS, Coffman CJ, Geiselman PJ, Kolotkin RL, Almirall D, Oddone EZ, Mayer SB, Gaillard LA, Turner M, Smith VA, Voils CI. Considering patient diet preference to optimize weight loss: design considerations of a randomized trial investigating the impact of choice. Contemporary clinical trials. 2013 May 1; 35(1):106-16.
- Yancy WS, McVay MA, Brinkworth GD. Adherence to diets for weight loss. [Editorial]. JAMA : the journal of the American Medical Association. 2013 Dec 25; 310(24):2676.
- Yancy WS. Peer Support Significantly Improves Compliance in Veterans with Diabetes. U. S. Medicine. 2012 Nov 20.
- Yancy WS. High-Fat Diets for Weight Management. For symposium entitled “Dietary and Lifestyle Behaviors in Cardiovascular Prevention: Beyond Statins”. Paper presented at: American Heart Association Annual Scientific Sessions; 2015 Nov 7; Chicago, IL.
- Yancy WS, Coffman CJ, Smith V, Mayer SB, McVay M, Kolotkin RL, Geiselman PJ, Oddone EZ, Voils CI. Improving weight loss: Is it a matter of (diet) choice? Presented at: Obesity Society Annual Scientific Meeting; 2014 Nov 4; Boston, MA.
- McVay M, Voils CI, Smith V, Geiselman P, Coffman CJ, Yancy WS. Can congruency between food preferences and weight loss dietary approach improve weight loss? Poster session presented at: Obesity Society Annual Scientific Meeting; 2014 Nov 2; Boston, MA.
- Yancy WS, Coffman CJ, Smith V, Mayer SB, Kolotkin RL, Geiselman PJ, McVay M, Oddone EZ, Voils CI. Allowing patient choice between two diverse diets did not improve weight loss. Presented at: Society of General Internal Medicine Annual Meeting; 2014 Apr 23; San Diego, CA.
- McVay M, Jeffreys AL, Olsen MK, Voils CI, King HA, Yancy WS. The relationship between pre-treatment macronutrient intake and weight loss during a randomized trial of different diet approaches. Poster session presented at: Obesity Society Annual Scientific Meeting; 2013 Nov 15; Atlanta, GA.
- McVay M, Yancy WS, Vijan S, Van Scoyoc LM, Neelon B, Maciejewski ML. Effects of obesity-related health status changes on behavioral weight loss treatment utilization in an integrated healthcare setting. Presented at: Obesity Society Annual Scientific Meeting; 2013 Nov 15; Atlanta, GA.
- Yancy WS, Smith V, Coffman CJ, Mayer S, McVay M, Geiselman PJ, Kolotkin R, Oddone EZ, Voils CI. Characteristics of dieters choosing either a low carbohydrate or low fat diet in a randomized trial examining the impact of choice on weight loss. Presented at: Obesity Society Annual Scientific Meeting; 2013 Nov 15; Atlanta, GA.
- McVay M, Voils CI, Yancy WS. Effects of Pre-treatment Carbohydrate and Fat Intake on Weight Outcomes during Two Different Diet Approaches. Poster session presented at: VA Durham VAMC Annual Research Week; 2013 May 15; Durham, NC.
Treatment - Comparative Effectiveness