Effect of Allowing Choice of Diet on Weight Loss: A Randomized Trial

Factors associated with choice of behavioural weight loss program by adults with obesity

We assessed the preference for two behavioural weight loss programs, Diabetes Prevention Program (DPP) and Healthy Weight for Living (HWL) in adults with obesity. A cross-sectional survey was fielded on the Amazon Mechanical Turk. Eligibility criteria included reporting BMI ≥30 and at least two chronic health conditions. Participants read about the programs, selected their preferred program, and answered follow-up questions. The estimated probability of choosing either program was not significantly different from .5 (N = 1005, 50.8% DPP and 49.2% HWL, p = .61). Participants' expectations about adherence, weight loss magnitude, and dropout likelihood were associated with their choice (p < .0001). Non-White participants (p = .040) and those with monthly income greater than $4999 (p = .002) were less likely to choose DPP. Participants who had postgraduate education (p = .007), did not report high serum cholesterol (p = .028), and reported not having tried losing weight before (p = .025) were more likely to choose DPP. Those who chose HWL were marginally more likely to report that being offered two different programs rather than one would likely affect their decision to enrol in one of the two (p = .052). The enrolment into DPP and HWL was balanced, but race, educational attainment, income, previous attempt to lose weight, and serum cholesterol levels had significant associations with the choice of weight loss program.

A very low-carbohydrate diabetes prevention program for veterans with prediabetes: a single-arm mixed methods pilot study

Introduction

All Veterans Affairs (VA) Medical Centers offer the MOVE! Weight Management Program to help patients achieve and maintain a healthy weight through a calorie-restricted, low-fat diet and increased physical activity. Yet, most MOVE! participants do not achieve clinically significant weight loss of ≥5%. A carbohydrate-restricted diet may help more Veterans to achieve ≥5% weight loss.

Methods

This was a single-arm explanatory sequential mixed methods pilot study conducted in one VA health care system. Veterans with prediabetes and body mass index ≥25 kg/m2 were invited to participate in a group-based, virtual, very low-carbohydrate Diabetes Prevention Program (VLC-DPP) consisting of 23 sessions over 12 months. Participants were taught to follow a very low-carbohydrate eating pattern, defined as 20-35 grams of net carbohydrates per day. The primary outcomes were measures of feasibility and acceptability, including program uptake and session attendance. Secondary outcomes included change in weight, hemoglobin A1c, lipids, and patient-reported measures of food cravings, stress eating, perceived health status, and motivation. Interviews were conducted at 6 months to identify factors that facilitated or hindered participants' achievement of ≥5% weight loss.

Results

Among 108 screened Veterans, 21 enrolled in the study (19%), and 18 were included in the analytic cohort. On average, participants attended 12.4/16 weekly sessions and 3.6/8 bimonthly or monthly sessions. At 12 months, mean percent weight loss was 9.4% (SD = 10.7) with 9 participants (50%) achieving ≥5% weight loss. Three factors facilitated achievement of ≥5% weight loss among 10/16 interviewees: (1) enjoyment of low-carbohydrate foods; (2) careful monitoring of carbohydrate intake; and (3) reduced hunger and food cravings. Three factors hindered achievement of ≥5% weight loss among 6/16 interviewees: (1) food cravings, particularly for sweets; (2) challenges with maintaining a food log; and (3) difficulty with meal planning.

Conclusion

A VLC-DPP is feasible and acceptable and shows preliminary efficacy among Veterans with prediabetes. The program's weight loss effectiveness compared to standard MOVE! should be evaluated in a larger-scale trial. Such a program may be offered in addition to the standard MOVE! program to expand the menu of evidence-based lifestyle counseling options for Veterans.

Clinical Trial Registration

https://clinicaltrials.gov/ct2/show/NCT04881890, identifier NCT04881890.

Gender Differences in Unhealthy Lifestyle Behaviors among Adults with Diabetes in the United States between 1999 and 2018

Lifestyle management is important to patients with diabetes, but whether gender differences exist in lifestyle management is unclear. Data from the US National Health and Nutrition Examination Survey (NHANES 1999 to 2018) was used for this research. Gender differences were evaluated descriptively and using an odds ratio (OR) with a 95% confidence interval (CI). A total of 8412 participants (48% women) were finally included. Across these surveys, the incidences of poor diet (OR: 1.26 (95% CI, 1.12, 1.43)), smoking (1.58 (1.35, 1.84)), alcohol consumption (1.94 (1.68, 2.25)) and sedentary behavior (1.20 (1.04, 1.39)) were more common in men, while depression (0.47 (0.37, 0.59)), obesity (0.69 (0.61, 0.78)) and insufficient physical activity (0.56 (0.49, 0.65)) were more common in women. Reductions in poor diet were greater in men between 1999 and 2000 and 2017 and 2018 (p = 0.037), while the mean body mass index (BMI) levels (p = 0.019) increased more among women. Furthermore, several gender differences were found to be related to age, race/ethnicity and marital/insurance/employment statuses. Our research found gender differences in diabetes-related unhealthy lifestyle behaviors and provides reference data for implementing measures to reduce the gender differences. Further work to reduce gender-specific barriers to a healthy lifestyle is warranted in order to further improve diabetes management.

Scope of Use and Effectiveness of Dietary Interventions for Improving Health-Related Outcomes in Veterans: A Systematic Review

Military veterans often have numerous physical and mental health conditions and can face unique challenges to intervention and management. Dietary interventions can improve the outcomes in many health conditions. This study aimed to evaluate the scope of health conditions targeted with dietary interventions and the effectiveness of these interventions for improving health-related outcomes in veterans. A systematic literature review was performed following PRISMA guidelines to identify and evaluate studies related to veterans and dietary interventions. Five electronic databases were searched, identifying 2669 references. Following screening, 35 studies were evaluated, and 18 were related to a US national veteran weight-loss program. The included studies were critically appraised, and the findings were narratively synthesized. Study designs ranged from randomised controlled trials to cohort studies and were predominantly U.S. based. The intervention durations ranged from one to 24 months. The mean subject age ranged from 39.0 to 69.7 years, with often predominantly male participants, and the mean body mass index ranged from 26.4 to 42.9 kg/m². Most dietary interventions for veterans were implemented in populations with overweight/obesity or chronic disease and involved single dietary interventions or dietary components of holistic lifestyle interventions. The most common primary outcome of interest was weight loss. The success of dietary interventions was generally moderate, and barriers included poor compliance, mental health conditions and large drop-out rates. The findings from this review illustrate the need for further refinement of dietary and lifestyle interventions for the management of veterans with chronic health conditions.

Low-carbohydrate versus balanced-carbohydrate diets for reducing weight and cardiovascular risk

BACKGROUND

Debates on effective and safe diets for managing obesity in adults are ongoing. Low-carbohydrate weight-reducing diets (also known as 'low-carb diets') continue to be widely promoted, marketed and commercialised as being more effective for weight loss, and healthier, than 'balanced'-carbohydrate weight-reducing diets.

OBJECTIVES

To compare the effects of low-carbohydrate weight-reducing diets to weight-reducing diets with balanced ranges of carbohydrates, in relation to changes in weight and cardiovascular risk, in overweight and obese adults without and with type 2 diabetes mellitus (T2DM).

SEARCH METHODS

We searched MEDLINE (PubMed), Embase (Ovid), the Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science Core Collection (Clarivate Analytics), ClinicalTrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) up to 25 June 2021, and screened reference lists of included trials and relevant systematic reviews. Language or publication restrictions were not applied.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in adults (18 years+) who were overweight or living with obesity, without or with T2DM, and without or with cardiovascular conditions or risk factors. Trials had to compare low-carbohydrate weight-reducing diets to balanced-carbohydrate (45% to 65% of total energy (TE)) weight-reducing diets, have a weight-reducing phase of 2 weeks or longer and be explicitly implemented for the primary purpose of reducing weight, with or without advice to restrict energy intake.  DATA COLLECTION AND ANALYSIS: Two review authors independently screened titles and abstracts and full-text articles to determine eligibility; and independently extracted data, assessed risk of bias using RoB 2 and assessed the certainty of the evidence using GRADE. We stratified analyses by participants without and with T2DM, and by diets with weight-reducing phases only and those with weight-reducing phases followed by weight-maintenance phases. Primary outcomes were change in body weight (kg) and the number of participants per group with weight loss of at least 5%, assessed at short- (three months to < 12 months) and long-term (≥ 12 months) follow-up.

MAIN RESULTS

We included 61 parallel-arm RCTs that randomised 6925 participants to either low-carbohydrate or balanced-carbohydrate weight-reducing diets. All trials were conducted in high-income countries except for one in China. Most participants (n = 5118 randomised) did not have T2DM. Mean baseline weight across trials was 95 kg (range 66 to 132 kg). Participants with T2DM were older (mean 57 years, range 50 to 65) than those without T2DM (mean 45 years, range 22 to 62). Most trials included men and women (42/61; 3/19 men only; 16/19 women only), and people without baseline cardiovascular conditions, risk factors or events (36/61). Mean baseline diastolic blood pressure (DBP) and low-density lipoprotein (LDL) cholesterol across trials were within normal ranges. The longest weight-reducing phase of diets was two years in participants without and with T2DM. Evidence from studies with weight-reducing phases followed by weight-maintenance phases was limited. Most trials investigated low-carbohydrate diets (> 50 g to 150 g per day or < 45% of TE; n = 42), followed by very low (≤ 50 g per day or < 10% of TE; n = 14), and then incremental increases from very low to low (n = 5). The most common diets compared were low-carbohydrate, balanced-fat (20 to 35% of TE) and high-protein (> 20% of TE) treatment diets versus control diets balanced for the three macronutrients (24/61). In most trials (45/61) the energy prescription or approach used to restrict energy intake was similar in both groups. We assessed the overall risk of bias of outcomes across trials as predominantly high, mostly from bias due to missing outcome data. Using GRADE, we assessed the certainty of evidence as moderate to very low across outcomes.  Participants without and with T2DM lost weight when following weight-reducing phases of both diets at the short (range: 12.2 to 0.33 kg) and long term (range: 13.1 to 1.7 kg).  In overweight and obese participants without T2DM: low-carbohydrate weight-reducing diets compared to balanced-carbohydrate weight-reducing diets (weight-reducing phases only) probably result in little to no difference in change in body weight over three to 8.5 months (mean difference (MD) -1.07 kg, (95% confidence interval (CI) -1.55 to -0.59, I2 = 51%, 3286 participants, 37 RCTs, moderate-certainty evidence) and over one to two years (MD -0.93 kg, 95% CI -1.81 to -0.04, I2 = 40%, 1805 participants, 14 RCTs, moderate-certainty evidence); as well as change in DBP and LDL cholesterol over one to two years. The evidence is very uncertain about whether there is a difference in the number of participants per group with weight loss of at least 5% at one year (risk ratio (RR) 1.11, 95% CI 0.94 to 1.31, I2 = 17%, 137 participants, 2 RCTs, very low-certainty evidence).  In overweight and obese participants with T2DM: low-carbohydrate weight-reducing diets compared to balanced-carbohydrate weight-reducing diets (weight-reducing phases only) probably result in little to no difference in change in body weight over three to six months (MD -1.26 kg, 95% CI -2.44 to -0.09, I2 = 47%, 1114 participants, 14 RCTs, moderate-certainty evidence) and over one to two years (MD -0.33 kg, 95% CI -2.13 to 1.46, I2 = 10%, 813 participants, 7 RCTs, moderate-certainty evidence); as well in change in DBP, HbA1c and LDL cholesterol over 1 to 2 years. The evidence is very uncertain about whether there is a difference in the number of participants per group with weight loss of at least 5% at one to two years (RR 0.90, 95% CI 0.68 to 1.20, I2 = 0%, 106 participants, 2 RCTs, very low-certainty evidence).  Evidence on participant-reported adverse effects was limited, and we could not draw any conclusions about these.  AUTHORS' CONCLUSIONS: There is probably little to no difference in weight reduction and changes in cardiovascular risk factors up to two years' follow-up, when overweight and obese participants without and with T2DM are randomised to either low-carbohydrate or balanced-carbohydrate weight-reducing diets.

Total Diet Replacement Within an Integrated Intensive Lifestyle Intervention for Remission of Type 2 Diabetes: Lessons From DiRECT

The prognosis for people with type 2 diabetes (T2D) remains concerning, yet its seriousness is often underestimated. T2D is a manifestation, in susceptible individuals, of the disease-process of obesity, and at diagnosis, 10-year survival rates for T2D are around 50%. Here, we will examine: (a) the role of weight loss in T2D, (b) use of total diet replacements (TDRs) to induce weight loss, (c) the Diabetes Remission Clinical Trial (DiRECT) protocol and key results, (d) other dietary interventions related to T2D remission, (e) remission in real life, and (f) future directions. Remission of short-duration T2D will usually require 10-15% body weight loss, and results from the DiRECT trial demonstrated that this can be achieved within routine care in nearly half of all people undertaking a supported, TDR-led behavioural weight management programme. In light of these findings, which have since been replicated in the Diabetes Intervention Accentuating Diet and Enhancing Metabolism (DIADEM-I) trial conducted in the Middle East and North Africa, it is now time to prioritize weight loss programmes for T2D remission from diagnosis, and with increasing acceptance and availability of digital healthcare, there is an opportunity to scale up delivery of remission programmes in a cost effective manner.

The effect of choice interventions on retention-related, behavioural and mood outcomes: a systematic review with meta-analysis

The provision of choice within interventions has been associated with increased motivation, engagement and interest, as well as improved clinical outcomes. Existing reviews are limited by their wide inclusion criteria or by not assessing behaviour change and mood outcomes. This review examines whether participant-driven choice-based interventions specifically are more likely to be enjoyed and accepted by participants compared to no-choice interventions, and whether this impacts on intervention outcomes in terms of behaviour change or mood. Forty-four randomised controlled trials were identified for inclusion. Random effects meta-analyses were performed for retention-related outcomes (drop-out, adherence and satisfaction), and aggregate behaviour change and mood outcomes. Choice-based interventions resulted in significantly less participant drop-out and increased adherence compared to interventions not offering choice. Results for the behaviour change and mood analyses were mixed. This meta-analytic review demonstrates that choice-based interventions may enhance participant retention and adherence, thus researchers and clinicians alike should consider the provision of choice when designing research and interventions. The evidence for the role of choice in behaviour change and mood is less convincing, and there is a need for more, higher quality research in this area.

A randomized feasibility pilot trial of a financial incentives intervention for dietary self-monitoring and weight loss in adults with obesity

Financial incentives could be used to improve adherence to behavioral weight loss interventions, increasing their effectiveness. This Phase IIb randomized pilot study evaluated the feasibility and acceptability of a study protocol for providing financial incentives for dietary self-monitoring and/or weight loss. Community-dwelling adults with obesity were enrolled in a 24 week, group-based weight loss program. Participants were randomized in a 2 × 2 factorial design to receive financial incentives for both dietary self-monitoring and weekly weight loss, just one, or neither. Participants could earn up to $300, evolving from fixed weekly payments to intermittent, variable payments. The notice of reward was provided by text message. The study was conducted in three successive cohorts to evaluate study procedure changes, including dietary approach, recruitment and retention strategies, text messaging, and incentives. Descriptive statistics calculated separately for each cohort described study performance relative to predefined targets for recruitment, including minority representation; retention; adherence; and weight loss. Acceptability was assessed via postintervention qualitative interviews. In Cohort 1 (n = 34), a low-carbohydrate diet was used. Recruitment, retention, adherence, and weight loss were adequate, but minority representation was not. For Cohort 2 (n = 31), employing an additional recruitment method and switching to a reduced-calorie diet yielded adequate recruitment, minority representation, retention, and adherence but less weight loss. Returning to a low-carbohydrate diet in Cohort 3 (n = 28) yielded recruitment, minority representation, retention, adherence, and weight loss similar to Cohort 2. Participant feedback informed changes to text message timing and content and incentive amount. Through successive cohorts, we optimized recruitment and retention strategies and text messaging. An adequately powered trial is warranted to evaluate the efficacy of these incentive structures for reducing weight. The trial registration number is NCT02691260.

Eating Behavior after Bariatric Surgery (EBBS) Questionnaire: a New Validated Tool to Quantify the Patients' Compliance to Post-Bariatric Dietary and Lifestyle Suggestions

PURPOSE

In the management of bariatric surgery follow-up, a multidisciplinary approach allows to evaluate the weight loss maintenance and the dietary and lifestyle changes adherence. The main aim of this study is to create and to validate a questionnaire (eating behavior after bariatric surgery (EBBS)) to objectivize the compliance to dietary/lifestyle suggestions after bariatric surgery.

MATERIALS AND METHODS

An observational retrospective monocentric clinical trial was carried out at the Bariatric Surgery Unit of Modena, Italy. All weight-related data of bariatric surgery patients collected during the multidisciplinary post-surgical path were recorded. EBBS questionnaire and three validated psychological tests were administered. EBBS includes 11 questions concerning food (domain A), drinks (B), behaviors (C), and lifestyle (S). All data analyzed in the study were collected during the same visit.

RESULTS

In 41 enrolled patients (52.2 + 11.9 years), the total weight loss after surgery was 44.87 + 18.37 kg (- 35.40 + 11.60%), with a weight loss maintenance of 86.92 + 14.30%. The EBBS questionnaire showed a good internal validity (Cronbach's alpha 0.743, Hotelling's T-square test p < 0.001). The S domain was directly related with the percentage of weight loss maintained (p = 0.048), suggesting that the frequent physical activity and the periodic weight self-check are the most predictive behaviors to obtain weight control. None of the psychological questionnaires appeared related to the weight trend.

CONCLUSIONS

We validated for the first time a 11-item self-filling questionnaire allowing to quantify the adaption to dietary/lifestyle suggestions provided after bariatric surgery. EBBS questionnaire could be a useful tool both in clinical and research setting to monitor the patient's adherence to post-surgical indications and to identify predictive factors for bariatric surgery efficacy.

Greater Loss of Central Adiposity from Low-Carbohydrate versus Low-Fat Diet in Middle-Aged Adults with Overweight and Obesity

The objective of this study is to determine whether middle-aged adults prescribed a low carbohydrate-high fat (LCHF) or low fat (LF) diet would have greater loss of central fat and to determine whether the insulin resistance (IR) affects intervention response. A total of 50 participants (52.3 ± 10.7 years old; 36.6 ± 7.4 kg/m2 BMI; 82% female) were prescribed either a LCHF diet (n = 32, carbohydrate: protein: fat of 5%:30%:65% without calorie restriction), or LF diet (n = 18, 63%:13–23%: 10–25% with calorie restriction of total energy expenditure—500 kcal) for 15 weeks. Central and regional body composition changes from dual-x-ray absorptiometry and serum measures were compared using paired t-tests and ANCOVA with paired contrasts. IR was defined as homeostatic model assessment (HOMA-IR) > 2.6. Compared to the LF group, the LCHF group lost more android (15.6 ± 11.2% vs. 8.3 ± 8.1%, p < 0.01) and visceral fat (18.5 ± 22.2% vs. 5.1 ± 15.8%, p < 0.05). Those with IR lost more android and visceral fat on the LCHF verses LF group (p < 0.05). Therefore, the clinical prescription to a LCHF diet may be an optimal strategy to reduce disease risk in middle-aged adults, particularly those with IR.

Dietary interventions for obesity: clinical and mechanistic findings

Dietary modification is central to obesity treatment. Weight loss diets are available that include various permutations of energy restriction, macronutrients, foods, and dietary intake patterns. Caloric restriction is the common pathway for weight reduction, but different diets may induce weight loss by varied additional mechanisms, including by facilitating dietary adherence. This narrative Review of meta-analyses and select clinical trials found that lower-calorie diets, compared with higher-calorie regimens, reliably induced larger short-term (<6 months) weight losses, with deterioration of this benefit over the long term (>12 months). Few significant long-term differences in weight loss were observed for diets of varying macronutrient composition, although some regimens were found to have short-term advantages (e.g., low carbohydrate versus low fat). Progress in improving dietary adherence, which is critical to both short- and long-term weight loss, could result from greater efforts to identify behavioral and metabolic phenotypes among dieters.

Protocol for Partner2Lose: A randomized controlled trial to evaluate partner involvement on long-term weight loss

Background

Behavioral interventions produce clinically significant weight reduction, with many participants regaining weight subsequently. Most interventions focus on an individual, but dietary and physical activity behaviors occur with, or are influenced by, domestic partners. According to interdependence theory, couples who approach behavior change as a problem to be tackled together versus independently are more likely to utilize communal coping processes to promote behavior change. We utilized interdependence theory to develop a partner-assisted intervention to increase long-term weight loss.

Methods

Community-dwelling individuals (index participants) cohabitating with a partner with 1) overweight and at least one obesity-related comorbidity or 2) obesity are randomized to participate in a standard weight management program alone or with their partner. The weight management program involves biweekly, in-person, group sessions focusing on weight loss for six months, followed by three group sessions and nine telephone calls focusing on weight loss maintenance for twelve months. In the partner-assisted arm, partners participate in half of the group sessions and telephone calls. Couples receive training in principles of cognitive behavioral therapy for couples, including sharing thoughts and feelings and joint problem solving, to increase communal coping. The primary outcome is participant weight loss at 24 months, with caloric intake and moderate-intensity physical activity as secondary outcomes. Partner weight and caloric intake will also be analyzed. Mediation analyses will examine the role of interdependence variables and social support.

Discussion

This trial will provide knowledge about effective ways to promote long-term weight loss and the role of interdependence constructs in weight loss.

Clinical trials identifier: NCT 03801174.

Sodium Glucose Co-Transporter 2 Inhibition Does Not Favorably Modify the Physiological Responses to Dietary Counselling in Diabetes-Free, Sedentary Overweight and Obese Adult Humans

Sedentary obesity is associated with increased risk of many cardio-metabolic diseases, including type 2 diabetes. Weight loss is therefore a desirable goal for sedentary adults with obesity. Weight loss is also a well-documented side effect of sodium glucose co-transporter 2 (SGLT2) inhibition, a pharmaceutical strategy for diabetes treatment. We hypothesized that, compared with placebo, SGLT2 inhibition as an adjunct to out-patient dietary counselling for weight loss would lead to more favorable modification of body mass and composition, and greater improvement in glucose regulation and lipid profile. Using a randomized, double-blind, repeated measures parallel design, 50 sedentary men and women (body mass index: 33.4 ± 4.7 kg/m²; mean ± SD) were assigned to 12 weeks of dietary counselling, supplemented with daily ingestion of either a placebo or SGLT2 inhibitor (dapagliflozin: up to 10 mg/day). Dietary counselling favorably modified body mass, body fat, glucose regulation, and fasting concentrations of triglyceride and very low-density lipoprotein cholesterol (main effects of counselling: p < 0.05); SGLT2 inhibition did not influence any of these adaptations (counselling × medication interactions: p > 0.05). However, SGLT2 inhibition when combined with dietary counselling led to greater loss of fat-free mass (counselling × medication interaction: p = 0.047) and attenuated the rise in high-density lipoprotein cholesterol (counselling × medication interaction: p = 0.028). In light of these data and the health implications of decreased fat-free mass, we recommend careful consideration before implementing SGLT2 inhibition as an adjunct to dietary counselling for weight loss in sedentary adults with obesity.

Early-phase study of a telephone-based intervention to reduce weight regain among bariatric surgery patients

OBJECTIVE

This study describes early-phase development of a behavioral intervention to reduce weight regain following bariatric surgery. We utilized the Obesity-Related Behavioral Intervention Trials model to guide intervention development and evaluation. We sought to establish recruitment, retention, and fidelity monitoring procedures; evaluate feasibility of utilizing weight from the electronic medical record (EMR) as an outcome; observe improvement in behavioral risk factors; and evaluate treatment acceptability.

METHOD

The intervention comprised 4 weekly telephone calls addressing behavior change strategies for diet, physical activity, and nutrition supplement adherence and 5 biweekly calls addressing weight loss maintenance constructs. Veterans (N = 33) who received bariatric surgery 9-15 months prior consented to a 16-week, pre-post study. Self-reported outcomes were obtained by telephone at baseline and 16 weeks. Clinic weights were obtained from the EMR 6 months pre- and postconsent. Qualitative interviews were conducted at 16 weeks to evaluate treatment acceptability. We aimed to achieve a recruitment rate of ≥ 25% and retention rate of ≥ 80%, and have ≥ 50% of participants regain < 3% of their baseline weight.

RESULTS

Results supported the feasibility of recruiting (48%) and retaining participants (93% provided survey data; 100% had EMR weight). Pre-post changes in weight (73% with < 3% weight regain) and physical activity (Cohen's ds 0.38 to 0.52) supported the potential for the intervention to yield clinically significant results. Intervention adherence (mean 7.8 calls of 9 received) and positive feedback from interviews supported treatment acceptability.

CONCLUSIONS

The intervention should be evaluated in an adequately powered randomized controlled trial. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Low Carbohydrate and Low-Fat Diets: What We Don't Know and Why we Should Know It

In the 1940s, the diet-heart hypothesis proposed that high dietary saturated fat and cholesterol intake promoted coronary heart disease in "at-risk" individuals. This hypothesis prompted federal recommendations for a low-fat diet for "high risk" patients and as a preventive health measure for everyone except infants. The low carbohydrate diet, first used to treat type 1 diabetes, became a popular obesity therapy with the Atkins diet in the 1970s. Its predicted effectiveness was based largely on the hypothesis that insulin is the causa prima of weight gain and regain via hyperphagia and hypometabolism during and after weight reduction, and therefore reduced carbohydrate intake would promote and sustain weight loss. Based on literature reviews, there are insufficient randomized controlled inpatient studies examining the physiological significance of the mechanisms proposed to support one over the other. Outpatient studies can be confounded by poor diet compliance such that the quality and quantity of the energy intake cannot be ascertained. Many studies also fail to separate macronutrient quantity from quality. Overall, there is no conclusive evidence that the degree of weight loss or the duration of reduced weight maintenance are significantly affected by dietary macronutrient quantity beyond effects attributable to caloric intake. Further work is needed.

Effect of Treatment Preference in Randomized Controlled Trials: Systematic Review of the Literature and Meta-Analysis

BACKGROUND

A significant limitation of the traditional randomized controlled trials is that strong preferences for (or against) one treatment may influence outcomes and/or willingness to receive treatment. Several trial designs incorporating patient preference have been introduced to examine the effect of treatment preference separately from the effects of individual interventions. In the current study, we summarized results from studies using doubly randomized preference trial (DRPT) or fully randomized preference trial (FRPT) designs and examined the effect of treatment preference on clinical outcomes.

METHODS

The current systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies using DRPT or FRPT design were identified using electronic databases, including PubMed, Cochrane Library, EMBASE, and Google Scholar between January 1989 and November 2018. All studies included in this meta-analysis were examined to determine the extent to which giving patients their preferred treatment option influenced clinical outcomes. The following data were extracted from included studies: study characteristics, sample size, study duration, follow-up, patient characteristics, and clinical outcomes. We further appraised risk of bias for the included studies using the Cochrane Collaboration's risk of bias tool.

RESULTS

The search identified 374 potentially relevant articles, of which 27 clinical trials utilized a DRPT or FRPT design and were included in the final analysis. Overall, patients who were allocated to their preferred treatment intervention were more likely to achieve better clinical outcomes [effect size (ES) = 0.18, 95% confidence interval (CI) 0.10-0.26]. Subgroup analysis also found that mental health as well as pain and functional disorders moderated the preference effect (ES = 0.23, 95% CI 0.11-0.36, and ES = 0.09, 95% CI 0.03-0.15, respectively).

CONCLUSIONS

Matching patients to preferred interventions has previously been shown to promote outcomes such as satisfaction and treatment adherence. Our analysis of current evidence showed that allowing patients to choose their preferred treatment resulted in better clinical outcomes in mental health and pain than giving them a treatment that is not preferred. These results underline the importance of incorporating patient preference when making treatment decisions.

Dietary modifications for weight loss and weight loss maintenance

Worldwide obesity rates remain at a rise, and to treat obesity is at the top of the global public health agenda. In 2013, the AHA/ACC/TOS obesity management guidelines were published, in essence suggesting that any dietary scheme seems to be effective for weight loss, as long as it can induce a sustainable energy deficit. In the present review, we update and critically discuss available information regarding dietary modifications for weight loss and weight loss maintenance, published after the 2013 guidelines. Regarding weight loss, we found no proof to support that a single dietary scheme, be it nutrient-, food group- or dietary pattern- based, is more efficacious of the other for achieving weight loss. For weight loss maintenance, published interventions point towards the same direction, although inconclusively. Most research explores the effect of weight loss regimes on weight loss maintenance and not the effect of the diet during weight loss maintenance, and this literature gap should be more thoroughly investigated.

Bariatric surgery, lifestyle interventions and orlistat for severe obesity: the REBALANCE mixed-methods systematic review and economic evaluation

BACKGROUND

Adults with severe obesity [body mass index (BMI) of ≥ 35 kg/m2] have an increased risk of comorbidities and psychological, social and economic consequences.

OBJECTIVES

Systematically review bariatric surgery, weight-management programmes (WMPs) and orlistat pharmacotherapy for adults with severe obesity, and evaluate the feasibility, acceptability, clinical effectiveness and cost-effectiveness of treatment.

DATA SOURCES

Electronic databases including MEDLINE, EMBASE, PsycINFO, the Cochrane Central Register of Controlled Trials and the NHS Economic Evaluation Database were searched (last searched in May 2017).

REVIEW METHODS

Four systematic reviews evaluated clinical effectiveness, cost-effectiveness and qualitative evidence for adults with a BMI of ≥ 35 kg/m2. Data from meta-analyses populated a microsimulation model predicting costs, outcomes and cost-effectiveness of Roux-en-Y gastric bypass (RYGB) surgery and the most effective lifestyle WMPs over a 30-year time horizon from a NHS perspective, compared with current UK population obesity trends. Interventions were cost-effective if the additional cost of achieving a quality-adjusted life-year is < £20,000-30,000.

RESULTS

A total of 131 randomised controlled trials (RCTs), 26 UK studies, 33 qualitative studies and 46 cost-effectiveness studies were included. From RCTs, RYGB produced the greatest long-term weight change [-20.23 kg, 95% confidence interval (CI) -23.75 to -16.71 kg, at 60 months]. WMPs with very low-calorie diets (VLCDs) produced the greatest weight loss at 12 months compared with no WMPs. Adding a VLCD to a WMP gave an additional mean weight change of -4.41 kg (95% CI -5.93 to -2.88 kg) at 12 months. The intensive Look AHEAD WMP produced mean long-term weight loss of 6% in people with type 2 diabetes mellitus (at a median of 9.6 years). The microsimulation model found that WMPs were generally cost-effective compared with population obesity trends. Long-term WMP weight regain was very uncertain, apart from Look AHEAD. The addition of a VLCD to a WMP was not cost-effective compared with a WMP alone. RYGB was cost-effective compared with no surgery and WMPs, but the model did not replicate long-term cost savings found in previous studies. Qualitative data suggested that participants could be attracted to take part in WMPs through endorsement by their health-care provider or through perceiving innovative activities, with WMPs being delivered to groups. Features improving long-term weight loss included having group support, additional behavioural support, a physical activity programme to attend, a prescribed calorie diet or a calorie deficit.

LIMITATIONS

Reviewed studies often lacked generalisability to UK settings in terms of participants and resources for implementation, and usually lacked long-term follow-up (particularly for complications for surgery), leading to unrealistic weight regain assumptions. The views of potential and actual users of services were rarely reported to contribute to service design. This study may have failed to identify unpublished UK evaluations. Dual, blinded numerical data extraction was not undertaken.

CONCLUSIONS

Roux-en-Y gastric bypass was costly to deliver, but it was the most cost-effective intervention. Adding a VLCD to a WMP was not cost-effective compared with a WMP alone. Most WMPs were cost-effective compared with current population obesity trends.

FUTURE WORK

Improved reporting of WMPs is needed to allow replication, translation and further research. Qualitative research is needed with adults who are potential users of, or who fail to engage with or drop out from, WMPs. RCTs and economic evaluations in UK settings (e.g. Tier 3, commercial programmes or primary care) should evaluate VLCDs with long-term follow-up (≥ 5 years). Decision models should incorporate relevant costs, disease states and evidence-based weight regain assumptions.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016040190.

FUNDING

The National Institute for Health Research Health Technology Assessment programme. The Health Services Research Unit and Health Economics Research Unit are core funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorate.

Do Parent Preferences for Child Conduct Problem Interventions Impact Parenting Outcomes? A Pilot Study in Community Children's Mental Health Settings

A pilot, doubly randomized preference trial was conducted to investigate the impact of providing parents preferences on parenting outcomes. Families with children having conduct problems were randomly assigned to a choice group in which they received their preferred treatment among the four intervention options or a no-choice group in which they were randomized assigned to one of the four options. Results of mixed-effects models showed that parents in the choice group who selected Parent Management Training-Oregon Model (PMTO) had better parenting outcomes over time compared to parents in the choice group who selected child therapy. It highlights the importance of incorporating parent preferences in the delivery of evidence-based treatments.

The Role of Choice in Weight Loss Strategies: A Systematic Review and Meta-Analysis

Effective strategies to achieve weight loss and long-term weight loss maintenance have proved to be elusive. This systematic review and meta-analysis aims to explore whether the choice of weight loss strategy is associated with greater weight loss. An electronic search was conducted using the MEDLINE (Medical Literature Analysis and Retrieval System Online, or MEDLARS Online), EMBASE (Excerpta Medica database), CINAHL (Cumulative Index to Nursing and Allied Health Literature), and PsycINFO (Database of Abstracts of Literature in the Field of Psychology, produced by the American Psychological Association and distributed on the association's APA PsycNET) databases for clinical trials and randomized controlled trials, investigating the role of choice in weight loss strategies. A total of nine studies were identified as meeting the pre-specified criteria. All of the studies included a 'Choice' or preference arm and a 'No Choice' arm or group who did not receive their preference as a control. A total of 1804 subjects were enrolled in these studies, with weight loss observed in both experimental and control groups of all studies, irrespective of dietary intervention, study duration, or follow-up length. Twelve interventions in nine trials were used for the meta-analysis, with results indicating a greater weight loss in the control groups, 1.09 ± 0.28 (overall mean difference in weight loss between groups ± standard error; p = 0). There was no significant effect of duration or attrition. In this meta-analysis, the choice of weight loss strategy did not confer a weight loss benefit.

The role of group cohesion in a group-based behavioral weight loss intervention

Behavioral weight loss interventions are often delivered in groups. Group cohesion may enhance program attendance and, thereby, weight loss. In this secondary analysis, our goals were to: (1a) assess whether group cohesion measured early in a behavioral weight loss intervention predicts program attendance and weight loss outcomes and, if so, (1b) explore whether attendance mediates the link between group cohesion and weight loss; (2) characterize the association between change in group cohesion and weight loss throughout the intervention. Veterans (n = 324) initiated a 16-week, group-based behavioral weight loss program involving biweekly in-person group visits. In linear regression models, early group cohesion was unrelated to group attendance or weight loss. Although group cohesion significantly increased during the intervention, this change was not associated with weight loss. These findings are consistent with the limited literature; however, they are inconsistent with theoretical assertions and clinical observations of the influence of group factors on outcomes.

Study protocol for Log2Lose: A feasibility randomized controlled trial to evaluate financial incentives for dietary self-monitoring and interim weight loss in adults with obesity

The obesity epidemic has negative physical, psychological, and financial consequences. Despite the existence of effective behavioral weight loss interventions, many individuals do not achieve adequate weight loss, and most regain lost weight in the year following intervention. We report the rationale and design for a 2×2 factorial study that involves financial incentives for dietary self-monitoring (yes vs. no) and/or interim weight loss (yes vs. no). Outpatients with obesity participate in a 24-week, group-based weight loss intervention. All participants are asked to record their daily dietary and liquid intake on a smartphone application (app) and to weigh themselves daily at home on a study-provided cellular scale. An innovative information technology (IT) solution collates dietary data from the app and weight from the scale. Using these data, an algorithm classifies participants weekly according to whether they met their group's criteria to receive a cash reward ranging from $0 to $30 for dietary self-monitoring and/or interim weight loss. Notice of the reward is provided via text message, and credit is uploaded to a gift card. This pilot study will provide information on the feasibility of using this novel IT solution to provide variable-ratio financial incentives in real time via its effects on recruitment, intervention adherence, retention, and cost. This study will provide the foundation for a comprehensive, adequately-powered, randomized controlled trial to promote short-term weight loss and long-term weight maintenance. If efficacious, this approach could reduce the prevalence, adverse outcomes, and costs of obesity for millions of Americans. Clinicaltrials.gov registration: NCT02691260.

New model for diabetes primary health care based on patient empowerment and the right to preventive health: the MIDE program

Objective.

To evaluate Mexico’s national Integrated Management of Diabetes in Stages (Manejo Integral de la Diabetes por Etapas, MIDE) program using three types of indicators: process, structure, and impact.

Methods.

A cross-sectional study was conducted using data for 97 452 people with diabetes (PWD) who participated in the MIDE patient empowerment program (PEP) at “MIDE modules” (standardized diabetes health care units) at Mexico’s Institute for Social Security and Services for State Workers (Instituto de Seguridad y Servicios Sociales de los Trabajadores del Estado, ISSSTE) hospital clinics and family medical clinics nationwide between 2007 and 2014. The program promotes diabetes patient empowerment and self-care through outpatient consultations with a multidisciplinary health care team supported by continuous training. Baseline data were compared with results post-program for the following indicators: process (metabolic control (MetC), based on glycated hemoglobin (HbA1c), triglyceride (TG), and total cholesterol (TC) levels); structure (number of MIDE modules installed at ISSSTE clinics and number of patients/health personnel accredited as diabetes experts/awarded diplomas); and impact (average number of patient illness days (IDs) and hospitalization episodes (HEs) per PWD over a 12-month period).

Results.

Over the seven-year study period, the proportion of patients with MetC (HbA1c < 7.0%, TG < 150 mg/dL, and TC < 200 mg/dL) increased significantly (from 35.4% to 60% (with a peak level of 62% in 2013); P < 0.001); average HbA1c, triglycerides, and total cholesterol per PWD dropped by 25%, 31%, and 11% respectively; average number of IDs and HEs per PWD over a 12-month period dropped by 38% and 41% respectively; a total of 140 MIDE modules were installed at ISSSTE clinics; and a total of 1 117 diplomas were awarded to 826 health professionals, and 2 613 PWD were accredited as “patient experts in diabetes.”

Conclusions.

The MIDE PEP is feasible, usable, and acceptable to PWD. The program improves MetC; reduces the frequency of IDs and HEs; and facilitates patient participation, the involvement of health personnel, and shared decision-making.

Environmental/lifestyle factors in the pathogenesis and prevention of type 2 diabetes

BACKGROUND

Environmental and lifestyle changes, in addition to the ageing of populations, are generally believed to account for the rapid global increase in type 2 diabetes prevalence and incidence in recent decades.

DISCUSSION

In this review, we present a comprehensive overview of factors contributing to diabetes risk, including aspects of diet quality and quantity, little physical activity, increased monitor viewing time or sitting in general, exposure to noise or fine dust, short or disturbed sleep, smoking, stress and depression, and a low socioeconomic status. In general, these factors promote an increase in body mass index. Since loss of β-cell function is the ultimate cause of developing overt type 2 diabetes, environmental and lifestyle changes must have resulted in a higher risk of β-cell damage in those at genetic risk. Multiple mechanistic pathways may come into play.

CONCLUSIONS

Strategies of diabetes prevention should aim at promoting a 'diabetes-protective lifestyle' whilst simultaneously enhancing the resistance of the human organism to pro-diabetic environmental and lifestyle factors. More research on diabetes-protective mechanisms seems warranted.

Environmental/lifestyle factors in the pathogenesis and prevention of type 2 diabetes

BACKGROUND

Environmental and lifestyle changes, in addition to the ageing of populations, are generally believed to account for the rapid global increase in type 2 diabetes prevalence and incidence in recent decades.

DISCUSSION

In this review, we present a comprehensive overview of factors contributing to diabetes risk, including aspects of diet quality and quantity, little physical activity, increased monitor viewing time or sitting in general, exposure to noise or fine dust, short or disturbed sleep, smoking, stress and depression, and a low socioeconomic status. In general, these factors promote an increase in body mass index. Since loss of β-cell function is the ultimate cause of developing overt type 2 diabetes, environmental and lifestyle changes must have resulted in a higher risk of β-cell damage in those at genetic risk. Multiple mechanistic pathways may come into play.

CONCLUSIONS

Strategies of diabetes prevention should aim at promoting a 'diabetes-protective lifestyle' whilst simultaneously enhancing the resistance of the human organism to pro-diabetic environmental and lifestyle factors. More research on diabetes-protective mechanisms seems warranted.

Jump starting shared medical appointments for diabetes with weight management: Rationale and design of a randomized controlled trial

BACKGROUND

Rates of glycemic control remain suboptimal nationwide. Medication intensification for diabetes can have undesirable side effects (weight gain, hypoglycemia), which offset the benefits of glycemic control. A Shared Medical Appointment (SMA) intervention for diabetes that emphasizes weight management could improve glycemic outcomes and reduce weight while simultaneously lowering diabetes medication needs, resulting in less hypoglycemia and better quality of life. We describe the rationale and design for a study evaluating a novel SMA intervention for diabetes that primarily emphasizes low-carbohydrate diet-focused weight management.

METHODS

Jump Starting Shared Medical Appointments for Diabetes with Weight Management (Jump Start) is a randomized, controlled trial that is allocating overweight Veterans (body mass index≥27kg/m²) with type 2 diabetes into two arms: 1) a traditional SMA group focusing on medication management and self-management counseling; or 2) an SMA group that combines low-carbohydrate diet-focused weight management (WM/SMA) with medication management. Hemoglobin A1c reduction at 48weeks is the primary outcome. Secondary outcomes include hypoglycemic events, diabetes medication use, weight, medication adherence, diabetes-related quality of life, and cost-effectiveness. We hypothesize that WM/SMA will be non-inferior to standard SMA for glycemic control, and will reduce hypoglycemia, diabetes medication use, and weight relative to standard SMA, while also improving quality of life and costs.

CONCLUSIONS

Jump Start targets two common problems that are closely related but infrequently managed together: diabetes and obesity. By focusing on diet and weight loss as the primary means to control diabetes, this intervention may improve several meaningful patient-centered outcomes related to diabetes.

Maintenance of Weight Loss After Initiation of Nutrition Training: A Randomized Trial

BACKGROUND

Weight regain after successful weight loss interventions is common.

OBJECTIVE

To establish the efficacy of a weight loss maintenance program compared with usual care in obese adults.

DESIGN

2-group, parallel, randomized trial stratified by initial weight loss (<10 kg vs. ≥10 kg), conducted from 20 August 2012 to 18 December 2015. Outcome assessors were blinded to treatment assignment. (ClinicalTrials.gov: NCT01357551).

SETTING

3 primary care clinics at the Veterans Affairs Medical Center in Durham and Raleigh, North Carolina.

PATIENTS

Obese outpatients (body mass index ≥30 kg/m2) who lost 4 kg or more of body weight during a 16-week, group-based weight loss program.

INTERVENTION

The maintenance intervention, delivered primarily by telephone, addressed satisfaction with outcomes, relapse-prevention planning, self-monitoring, and social support. Usual care involved no contact except for study measurements.

MEASUREMENTS

Primary outcome was mean weight regain at week 56. Secondary outcomes included self-reported caloric intake, walking, and moderate physical activity.

RESULTS

Of 504 patients in the initial program, 222 lost at least 4 kg of body weight and were randomly assigned to maintenance (n = 110) or usual care (n = 112). Retention was 85%. Most patients were middle-aged white men. Mean weight loss during initiation was 7.2 kg (SD, 3.1); mean weight at randomization was 103.6 kg (SD, 20.4). Estimated mean weight regain was statistically significantly lower in the intervention (0.75 kg) than the usual care (2.36 kg) group (estimated mean difference, 1.60 kg [95% CI, 0.07 to 3.13 kg]; P = 0.040). No statistically significant differences in secondary outcomes were seen at 56 weeks. No adverse events directly attributable to the intervention were observed.

LIMITATIONS

Results may not generalize to other settings or populations. Dietary intake and physical activity were self-reported. Duration was limited to 56 weeks.

CONCLUSION

An intervention focused on maintenance-specific strategies and delivered in a resource-conserving way modestly slowed the rate of weight regain in obese adults.

PRIMARY FUNDING SOURCE

Veterans Affairs Health Services Research and Development Service.

Behavioral Treatment for Veterans with Obesity: 24-Month Weight Outcomes from the ASPIRE-VA Small Changes Randomized Trial

BACKGROUND

Small Changes (SC) is a weight management approach that demonstrated superior 12-month outcomes compared to the existing MOVE!^® Weight Management Program at two Veterans Affairs (VA) sites. However, approaches are needed to help graduates of treatment continue to lose or maintain their weight over the longer term.

OBJECTIVE

The purpose of the present study was to examine the effectiveness of a second year of low-intensity SC support compared to support offered by the usual care MOVE! programs.

DESIGN

Following participation in the year-long Aspiring to Lifelong Health in VA (ASPIRE-VA) randomized controlled trial, participants were invited to extend their participation in their assigned program for another year. Three programs were extended to include six SC sessions delivered via telephone (ASPIRE-Phone) or an in-person group (ASPIRE-Group), or 12 sessions offered by the MOVE! programs.

PARTICIPANTS

Three hundred thirty-two overweight/obese veterans who consented to extend their participation in the ASPIRE-VA trial by an additional year.

MAIN MEASURES

Twenty-four-month weight change (kg).

KEY RESULTS

Twenty-four months after baseline, participants in all three groups had modest weight loss (-1.40 kg [-2.61 to -0.18] in the ASPIRE-Group, -2.13 kg [-3.43 to -0.83] in ASPIRE-Phone, and -1.78 kg [-3.07 to -0.49] in MOVE!), with no significant differences among the three groups. Exploratory post hoc analyses revealed that participants diagnosed with diabetes initially benefited from the ASPIRE-Group program (-2.6 kg [-4.37 to 0.83]), but experienced significant weight regain during the second year (+2.8 kg [0.92-4.69]) compared to those without diabetes.

CONCLUSIONS

Participants in all three programs lost weight and maintained a statistically significant, though clinically modest, amount of weight loss over a 24-month period. Although participants in the ASPIRE-Group initially had greater weight loss, treatment was not sufficient to sustain weight loss through the second year, particularly in veterans with diabetes. Consistent, continuous-care treatment is needed to address obesity in the VA.

Recruitment and Retention for a Weight Loss Maintenance Trial Involving Weight Loss Prior to Randomization

Objective

A weight loss maintenance trial involving weight loss prior to randomization is challenging to implement due to the potential for dropout and insufficient weight loss. We examined rates and correlates of non‐initiation, dropout, and insufficient weight loss during a weight loss maintenance trial.

Methods

The MAINTAIN trial involved a 16‐week weight loss program followed by randomization among participants losing at least 4 kg. Psychosocial measures were administered during a screening visit. Weight was obtained at the first group session and 16 weeks later to determine eligibility for randomization.

Results

Of 573 patients who screened as eligible, 69 failed to initiate the weight loss program. In adjusted analyses, failure to initiate was associated with lower age, lack of a support person, and less encouragement for making dietary changes. Among participants who initiated, 200 dropped out, 82 lost insufficient weight, and 222 lost sufficient weight for randomization. Compared to losing sufficient weight, dropping out was associated with younger age and tobacco use, whereas losing insufficient weight was associated with non‐White race and controlled motivation for physical activity.

Conclusions

Studies should be conducted to evaluate strategies to maximize recruitment and retention of subgroups that are less likely to initiate and be retained in weight loss maintenance trials.

Food preferences and weight change during low-fat and low-carbohydrate diets

Understanding associations between food preferences and weight loss during various effective diets could inform efforts to personalize dietary recommendations and provide insight into weight loss mechanisms. We conducted a secondary analysis of data from a clinical trial in which participants were randomized to either a 'choice' arm, in which they were allowed to select between a low-fat diet (n = 44) or low-carbohydrate diet (n = 61), or to a 'no choice' arm, in which they were randomly assigned to a low-fat diet (n = 49) or low-carbohydrate diet (n = 53). All participants were provided 48 weeks of lifestyle counseling. Food preferences were measured at baseline and every 12 weeks thereafter with the Geiselman Food Preference Questionnaire. Participants were 73% male and 51% African American, with a mean age of 55. Baseline food preferences, including congruency of food preferences with diet, were not associated with weight outcomes. In the low-fat diet group, no associations were found between changes in food preferences and weight over time. In the low-carbohydrate diet group, increased preference for low-carbohydrate diet congruent foods from baseline to 12 weeks was associated with weight loss from 12 to 24 weeks. Additionally, weight loss from baseline to 12 weeks was associated with increased preference for low-carbohydrate diet congruent foods from 12 to 24 weeks. Results suggest that basing selection of low-carbohydrate diet or low-fat diet on food preferences is unlikely to influence weight loss. Congruency of food preferences and weight loss may influence each other early during a low-carbohydrate diet but not low-fat diet, possibly due to different features of these diets.

CLINICAL TRIAL REGISTRY

NCT01152359.