Changes in self-efficacy and dietary adherence: the impact on weight loss in the PREFER study.

Findings from studies examining self-efficacy and its relationship to weight loss have been inconsistent. We examined self-efficacy specific to changing eating behaviors in the PREFER trial, an 18-month behavioral weight-loss study, to determine if self-efficacy and dietary adherence were associated with weight change, and what impact self-efficacy had on weight change after controlling for adherence. Measurements included the weight efficacy lifestyle (WEL) questionnaire, body weight, self-reported fat gram intake, kilocalorie intake, and adherence to kilocalorie and fat gram goals at baseline, 6, 12, and 18 months. The sample (N = 170) was 88.2% female and 70.0% Caucasian; the mean age was 44.1 years (SD = 8.8). Mean weight loss at 18 months was 4.64% (SD = 6.24) of baseline body weight and the mean increase in self-efficacy was 11.70% (SD = 38.61). Self-efficacy improved significantly over time (p = 0.04) and was associated with weight loss (p = 0.02). Adherence to the fat gram goal was associated with weight loss (p = 0.0003), and self-efficacy remained associated with weight loss after controlling for fat gram adherence (p = 0.0001). Consistent with self-efficacy theory, improvement in self-efficacy over time supported greater weight loss. Adherence to the fat gram goal also influenced weight loss.

Using instrumented paper diaries to document self-monitoring patterns in weight loss.

Self-monitoring of eating is associated with successful weight loss, but adherence is imperfect and deteriorates over time. Moreover, intentionally or not, many individuals have difficulty keeping faithful records. We used instrumented paper diaries (IPDs) to study self-monitoring in randomly chosen participants in the PREFER trial, a behavioral treatment for weight-loss study. The diaries they used to self-report eating were periodically replaced with IPDs at various times during an 18-month weight-loss program, consisting of three successive phases: intense treatment (n=35), less-intense treatment (n=13), and maintenance (n=16). We compared electronically documented self-monitoring data, showing when and how often IPDs were used, with self-reported data, then compared the electronically validated adherence and weight loss. Self-reported diary usage exceeded IPD-documented usage while the electronic data demonstrated a significant decline in self-monitoring over time. Diary recording often was not timely. Percentage weight lost correlated significantly with frequency of IPD use (p=.001) and the number of diary entries made within 15 min of opening the IPD (p=.002). This is the first study to document patterns of self-monitoring among participants in a weight-loss program, which demonstrated that individuals may falsify the times and frequency of self-monitoring. Furthermore, our results showed that adherence to self-monitoring and the timeliness of recording significantly correlate with improved weight loss.

Effects of a vegetarian diet and treatment preference on biochemical and dietary variables in overweight and obese adults: a randomized clinical trial.

BACKGROUND: A vegetarian diet may lead to numerous health benefits, including weight loss. OBJECTIVE: We examined the joint effects of personal preference of dietary treatment and a calorie-restricted, low-fat lactoovovegetarian diet (LOV-D) compared with a standard calorie-restricted, low-fat omnivorous diet (STD-D) on changes in weight, total cholesterol, ratio of LDL to HDL cholesterol (LDL:HDL cholesterol), triacylglycerols, insulin resistance, and macronutrient intake during an 18-mo study. DESIGN: This was a randomized clinical trial of 176 overweight and obese adults who were recruited and randomly assigned first to 1 of 2 preference conditions (yes or no). If assigned to Preference-No, they were randomly assigned to 1 of the 2 diet conditions (STD-D or LOV-D). If assigned to Preference-Yes, they were assigned to the diet they indicated as preferred at screening. The 12-mo intervention was followed by a 6-mo maintenance phase. RESULTS: Participants were mainly women (86.9%) and white (70.5%); 75% completed the 18-mo study. A significant interaction between preference and dietary treatment was not observed for any of the outcome variables. However, participants in the Preference-No groups significantly decreased their triacylglycerols (P = 0.04). The only effect observed for diet was a borderline significant decrease in LDL:HDL cholesterol for the LOV-D group (P = 0.06). Within the LOV-D groups, those who were 100% adherent to the LOV-D had significant and marginally significant reductions in monounsaturated fat (P = 0.02) and total fat (P = 0.05) intakes at 18 mo. CONCLUSIONS: Our findings suggest that neither prescribing a vegetarian diet nor allowing persons to choose their preferred diet had a significant effect on outcome measures. However, all participants had a significant reduction in total energy and fat intakes and an increase in energy expenditure, which was reflected in reduced body weight. This clinical trial was registered at www.clinicaltrials.gov as NCT00330629.

A randomized clinical trial testing treatment preference and two dietary options in behavioral weight management: preliminary results of the impact of diet at 6 months--PREFER study.

OBJECTIVE: The PREFER study objectives were to examine potential differences in weight loss during a standard behavioral intervention between subjects assigned to one of two calorie- and fat-restricted diets [standard behavior treatment (SBT) and lacto-ovo-vegetarian ([SBT+LOV)], with or without regard to their preferred dietary treatment. This article reports the differences in outcomes between diet groups after the first 6 months of the intervention. RESEARCH METHODS AND PROCEDURES: The study used a four-group design. Subjects (n = 182) were randomized to a treatment preference group and then to a dietary treatment group. For this report, preference groups were combined to permit comparisons by dietary treatment only (SBT, n = 98; SBT+LOV, n = 84). Additional analyses compared SBT+LOV subjects who were 100% adherent (did not consume any meat, fish, or poultry, n = 47) to those who were <100% adherent (n = 24). RESULTS: Significant differences were seen in the baseline to 6-month change scores between the two groups for carbohydrate consumption (p = 0.013), protein consumption (p < 0.001), polyunsaturated-to-saturated fat ratio (p = 0.009), and low-density lipoprotein-cholesterol (LDL-C) level (p = 0.013). Among SBT+LOV subjects, those who were 100% adherent experienced greater reductions in weight (p < 0.001), total cholesterol (p = 0.026), LDL-C (p = 0.034), and glucose (p = 0.002) and consumed less fat (p = 0.030) compared with those who were <100% adherent. DISCUSSION: Differences between dietary treatment groups at 6 months were minimal, most likely because one-third of the SBT+LOV group did not follow the vegetarian diet and because both groups had the same calorie and fat restrictions. SBT+LOV subjects who were 100% adherent were more successful at both weight loss and cholesterol reduction than those who were <100% adherent, suggesting that vegetarian diets are efficacious for weight and cholesterol control.

Ancillary study to the PREFER trial: a descriptive study of participants' patterns of self-monitoring--rationale, design and preliminary experiences.

BACKGROUND: The treatment of obesity, marked by a high rate of recidivism, lacks strategies that sustain the improved lifestyle behaviors that led to the weight loss. Self-monitoring, a behavioral strategy to increase awareness of one's behavior, is the cornerstone of behavioral treatment in weight loss management. However, adherence to self-monitoring is less than ideal. The actual patterns of self-monitoring of eating behaviors in weight loss treatment programs have not been studied previously; if done, these data could provide information on how self-monitoring patterns affect weight loss and if interventions can be developed that address deficits in self-monitoring. Technology now permits an instrumented paper-and-pencil diary to record the real time of individuals' self-monitoring behaviors (invivodata, inc.), thus providing more information about self-reported behaviors. This technology differs from PDA based products (ex. e-diary, e-trials, logpad, PICS) because, to the user, it is no different from a standard paper-and-pencil diary. METHODS: The purposes of this ancillary study are: (1) to describe the electronically recorded patterns of self-monitoring of eating behaviors by weight-loss study participants; (2) compare reported vs. electronically recorded self-monitoring; and (3) examine the relationship between the electronically validated adherence to self-monitoring goals and success in weight loss in a sub-sample of participants in the PREFER study. This paper describes the design, methods and preliminary 6-month results. RESULTS: Preliminary results reveal that participants frequently report recording their eating behavior during times when the binder was not opened. Two examples of data are shown that demonstrate the lack of concordance between the self-reported and the electronically recorded data. CONCLUSIONS: These unobtrusively collected electronic data can lead to the development of strategies that can promote improved adherence to self-monitoring.

PREFER study: a randomized clinical trial testing treatment preference and two dietary options in behavioral weight management--rationale, design and baseline characteristics.

BACKGROUND: Obesity, a disorder associated with a myriad of comorbidities, is increasing at an alarming rate around the world. Given that pharmacotherapy has limited available options and that bariatric surgery is reserved for those who are morbidly obese or who have significant comorbidities, the most common approach to the treatment of obesity is standard behavioral treatment. This approach includes behavior modification related to eating and activity habits. The purpose of this paper is to describe the rationale, design, methods and baseline sample characteristics of a randomized controlled trial of a behavioral intervention in weight loss management, referred to as the PREFER study. METHODS: The PREFER study, using a four-group design, includes: (1) a randomization scheme that permits participants to indicate a preferred dietary treatment approach, and (2) two dietary options, one of which is a lacto-ovo-vegetarian diet that has demonstrated potential for long-term adherence. The intervention (32 treatment sessions) is delivered over 12 months and is followed by a 6-month maintenance phase; final assessment occurs at 18 months. RESULTS: We screened 932 individuals and randomized 197 to the study: Treatment Preference-Yes (n=84) and Treatment Preference-No (n=98). To maintain a balance across the four treatment groups, 15 subjects who preferred the standard diet had to be discarded from the Treatment Preference-Yes group. Retention at 18 months for the first of three cohorts was 82%. CONCLUSIONS: The PREFER study is a single center study and is the first randomized controlled trial examining a lacto-ovo-vegetarian diet as part of weight loss treatment. The ethnically diverse sample includes males and females with a body mass index of 27 to 43. The study has the potential to make a contribution to understanding the role of treatment preference and the potential of a lacto-ovo-vegetarian diet for long-term weight loss.

Self-monitoring dietary intake: current and future practices.

This article reviews the literature on the use of paper diaries for self-monitoring food intake, identifies the strengths and limitations of paper-and-pencil diaries and their new counterpart, the electronic diary or personal digital assistant (PDA), and reports how participants were trained to use a PDA with dietary software in two pilot studies--one with hemodialysis patients and the other with participants in a weight loss study. The report of the pilot studies focuses on the practical issues encountered in training participants in the use of a PDA and addresses the pros and cons of different dietary software programs. Six hemodialysis patients were trained in the first study and seven participants attempting to lose or maintain their weight were trained in the second pilot study. The training focused on how to use a PDA and how to navigate the dietary software to self-monitor food intake. The goals of using the PDA were to improve adherence to the therapeutic diets and to self-monitoring. Lessons learned from the pilot studies are shared.