Factors associated with choice of a low-fat or low-carbohydrate diet during a behavioral weight loss intervention

Should carbohydrate-modified diets be the first option for weight loss in people with impaired glucose metabolism? A scoping review

While the "precision nutrition" movement is at an early stage of development, several investigations have compared low-fat versus carbohydrate (CHO)-modified diets (i.e., low-or-reduced-CHO, low glycemic index/load diets, and high-fiber) in people with normal versus impaired glucose metabolism. The purpose of this scoping review was to summarize evidence in support of the hypothesis that CHO-modified diets are more effective for weight loss among people with impaired glucose metabolism. Fifteen articles were included in this review: seven retrospective analyses of randomized clinical trials and eight prospective randomized clinical trials with prespecified hypotheses related to a diet (low-fat vs. CHO-modified) × phenotype (normal vs. impaired) interaction. Evidence in support of the hypothesis was identified in six of seven retrospective and three of eight prospective studies, which led to a recommendation of CHO-modified diets as a first-line option for people with impaired glucose metabolism. However, the evidence in support of this recommendation is relatively weak, and dietary prescriptions should consider additional contextual information that may influence overall dietary adherence. Additional and rigorous research using innovative randomized experimental approaches is needed for stronger dietary weight loss recommendations based on pretreatment glycemic status.

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.

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.

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.

Fat preference and fat intake in individuals with and without anorexia nervosa

Fat restriction is a characteristic eating behavior among individuals with anorexia nervosa (AN), and laboratory meal studies demonstrate restricted fat intake among low-weight patients. The Geiselman Food Preference Questionnaire-I^© (FPQ) is a validated self-report measure that yields a fat preference score (FPS). Prior research reported that patients with AN had a significantly lower FPS than did healthy control (HC) participants. The goal of the current study was to compare self-reported fat preference (FPS) to fat intake (multi-item meal (MIM) study) in low-weight ANs and HCs. Specific aims were 1) to determine if the FPS differed between ANs and HCs; 2) to determine if fat and energy intakes differed between ANs and HCs; and 3) to determine if the FPS was associated with fat and energy intakes in ANs and HCs. Forty-four female AN inpatients and 48 female HCs completed the FPQ and participated in a MIM study. Compared to HCs, ANs consumed less energy (469.1 ± 397.7 vs. 856.4 ± 346.8 kcal, p < 0.001), less fat (16.4 ± 20.4 vs. 36.7 ± 18.9 g, p < 0.001), and a smaller percentage of calories from fat (22.9 ± 13.8 vs. 36.6 ± 8.0%, p < 0.001) at the MIM. Compared to HCs, ANs also had a lower FPS (79.7 ± 27.4 vs. 102.3 ± 18.9, p < 0.001). The FPS was significantly and positively correlated with caloric intake (r = 0.481, p < 0.01), total fat (r = 0.453, p < 0.01), and the percentage of calories from fat (r = 0.37, p < 0.05) in ANs as well as in HCs (kcal: r = 0.583, p < 0.001; fat: r = 0.621, p < 0.001; % fat kcal: r = 0.601, p < 0.001). The FPS is related to objective measures of energy and fat intake in patients with AN as well as in healthy individuals.

PROP Nontaster Women Lose More Weight Following a Low-Carbohydrate Versus a Low-Fat Diet in a Randomized Controlled Trial

OBJECTIVE

Taste blindness to 6-n-propylthiouracil (PROP) associates with increased fat preference and intake. No studies have matched a diet to a woman's PROP phenotype to improve weight loss. This study investigated (1) whether PROP nontaster (NT) women would lose more weight following a low-carbohydrate (LC) diet than a low-fat (LF) diet, and (2) whether PROP supertaster (ST) women would lose more weight following a LF diet than a LC diet.

METHODS

One hundred seven women (BMI = 34.8 ± 0.5 kg/m² ), classified as PROP NTs (n = 47) and STs (n = 60), were randomized to a LC or LF diet within a 6-month lifestyle intervention. Assessments included 4-day dietary recalls and biobehavioral and psychosocial questionnaires.

RESULTS

At 6 months, NTs lost more weight following the LC than the LF diet (-8.5 ± 0.5 kg vs. -6.6 ± 0.5 kg, P = 0.008); there was no difference between STs following either diet (-8.8 ± 0.4 vs. -8.9 ± 0.5, P = 0.35). Dietary self-reports were unrelated to weight loss, and prescription of a LC diet associated with greater self-efficacy.

CONCLUSIONS

NT women lost more weight following the LC diet compared to the LF diet. Screening for PROP phenotype may help personalize diet therapy for NT women to optimize their short-term weight loss.

The effect of acute weight restoration on dietary fat preference in hospitalized patients with anorexia nervosa

OBJECTIVE

Individuals with anorexia nervosa (AN) restrict fat intake. The Geiselman Food Preference Questionnaire-I© (FPQ) is a validated self-report instrument that yields a fat preference score (>100 = high fat preference, <100 = low fat preference). The goal of the study was to assess the utility of the FPQ in patients with AN.

SPECIFIC AIMS

(1) to examine change in fat preference scores before and after weight restoration in hospitalized patients; and (2) to compare patients' scores before and after weight restoration to scores from healthy participants (HPs).

METHOD

The FPQ was completed by 88 patients and 115 HPs.

RESULTS

Compared with HPs, patients had significantly lower fat preference scores before (74.03 ± 32.03 vs. 102.93 ± 16.89, P < 0.001) and after (81.51 ± 26.89 vs. 102.92 ± 16.89, P < 0.001) weight restoration. Fat preference scores increased with weight gain (74.03 + 32.03 vs. 81.51 + 26.89, P < 0.01) but did not normalize in AN.

DISCUSSION

Acutely weight restored patients continue to endorse decreased preference for high fat foods. The FPQ may be a useful metric by which to assess improvements in diet during treatment. Further study is warranted to validate the FPQ against observed food intake in AN. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2017; 50:148-151).

Postmenopausal women with abdominal obesity choosing a nutritional approach for weight loss: A decisional needs assessment

OBJECTIVES

To identify the decisional needs of postmenopausal women with abdominal obesity choosing between two nutritional approaches for weight loss: a low-fat diet or a diet rich in fruit and vegetables.

STUDY DESIGN

Our descriptive qualitative study was based on the Ottawa Decision Support Framework.

MAIN OUTCOME MEASURES

Four focus groups were conducted with postmenopausal women. A thematic content analysis was performed to determine the decisional needs influencing the choice of a low-fat diet or a diet rich in fruit and vegetables.

RESULTS

Seventeen postmenopausal women participated in the study (median age 59 years). Most frequently reported decisional needs for each nutritional approach were sufficient levels of nutritional skills and knowledge, consideration of the physiological impacts and the sensory aspect of approaches, food availability, social support, finances and motivation. Partners, friends and daughters were considered as the most important individuals involved in the decision.

CONCLUSIONS

We identified several decisional needs influencing postmenopausal women when choosing between a low-fat diet and a diet rich in fruit and vegetables. These findings could inform the design of decision support interventions that address the decisional needs of women for making and implementing informed decisions about a nutritional approach for weight loss.

The Effects of Different High-Protein Low-Carbohydrates Proprietary Foods on Blood Sugar in Healthy Subjects

The aim of this study was to analyze the effects on blood sugar concentrations through the calculation of the glycemic score (GS) of 10 different high-protein low-carbohydrates (CHOs) proprietary foods that are commonly used as meals during very low-CHO ketogenic diets or during low-CHO diets. Fourteen healthy females were tested for their glycemic response curve elicited by 1000 kJ of glucose three times within a 3-week period (one test each week) compared with one of 10 test foods once on separate days twice a week. After determining the GS of each food in each individual, the mean GS of each test food was calculated. All test foods, compared with glucose, produced a significantly lower glycemic response. The GS of all test food resulted in being lower than 25 and the difference between the mean glycemia after the intake of glucose (mean 122 ± 15 mg/dL) and after the intake of the sweet test foods (mean 89 ± 7 mg/dL) was 33 mg/dL (P < .001), whereas the difference between the mean glycemia after the intake of glucose and after the intake of savory test foods (mean 91 ± 8 mg/dL) was of 31 mg/dL (P < .001).

CONCLUSIONS

The reformulation of ultraprocessed ready-to-consume foods in a low-CHO, high-protein version can produce a significantly lower glycemic response whilst maintaining the valued ready-to-use format and high palatability demanded by consumers. The low impact on postprandial glycemia and the nutritional characteristics of these proprietary foods makes them useful in both weight control management strategies and in the care management of diabetes.

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.

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

BACKGROUND

Choosing a diet rather than being prescribed one could improve weight loss.

OBJECTIVE

To examine whether offering choice of diet improves weight loss.

DESIGN

Double-randomized preference trial of choice between 2 diets (choice) versus random assignment to a diet (comparator) over 48 weeks. (ClinicalTrials.gov: NCT01152359).

SETTING

Outpatient clinic at a Veterans Affairs medical center.

PATIENTS

Outpatients with a body mass index of at least 30 kg/m2.

INTERVENTION

Choice participants received information about their food preferences and 2 diet options (low-carbohydrate diet [LCD] or low-fat diet [LFD]) before choosing and were allowed to switch diets at 12 weeks. Comparator participants were randomly assigned to 1 diet for 48 weeks. Both groups received group and telephone counseling for 48 weeks.

MEASUREMENTS

The primary outcome was weight at 48 weeks.

RESULTS

Of 105 choice participants, 61 (58%) chose the LCD and 44 (42%) chose the LFD; 5 (3 on the LCD and 2 on the LFD) switched diets at 12 weeks, and 87 (83%) completed measurements at 48 weeks. Of 102 comparator participants, 53 (52%) were randomly assigned to the LCD and 49 (48%) were assigned to the LFD; 88 (86%) completed measurements. At 48 weeks, estimated mean weight loss was 5.7 kg (95% CI, 4.3 to 7.0 kg) in the choice group and 6.7 kg (CI, 5.4 to 8.0 kg) in the comparator group (mean difference, -1.1 kg [CI, -2.9 to 0.8 kg]; P = 0.26). Secondary outcomes of dietary adherence, physical activity, and weight-related quality of life were similar between groups at 48 weeks.

LIMITATIONS

Only 2 diet options were provided. Results from this sample of older veterans might not be generalizable to other populations.

CONCLUSION

Contrary to expectations, the opportunity to choose a diet did not improve weight loss.