Table 1.
Study outlines.
| Author (Year) | Study Design | Study Population | Start (n) | End (n) (% of Attrition) | Strategy | Option to Change Diet | Study Outcome * Mean ± Standard Deviation ** Mean (95% Confidence Interval) |
|---|---|---|---|---|---|---|---|
| Borradaile et al. [23] | RCT, over 2 years. Baseline data collected, weekly data for 20 weeks, fortnightly for week 20–40 and every other month for remainder of 2 years. | 18–65 years BMI 30–40 kg/m2 |
250 | 157 (37.2%) |
Treatment preference assessed prior to, but independent of, randomization into either low-carbohydrate or low-fat diet. Preference congruent (n = 74); no strong preference (n = 98); preference incongruent (n = 78). |
No | At 24 months ** Treatment congruent (a); ↓7.7 kg (↓9.3 to ↓6.1) Treatment incongruent (b); ↓9.7 kg (↓11.4 to ↓8.1) No strong preference (c); ↓11.2 kg (↓12.6 to ↓9.7) p = 0.04 (a) and (b) p = 0.0004 (a) and (c) |
| Burke et al. [26] | RCT. Initial weekly sessions for 6 months, every 2 weeks for months 7 to 9, and monthly for months 10–12. Baseline data collected and every 6 months for 18 months. | 18–55 years BMI 27–43 kg/m2 |
176 | 132 (25%) |
Participants ranked their preference for a Lacto-ovo-vegetarian diet (LOV-D) or a Standard calorie- and fat-restricted diet (STD-D) on a 3-point Likert scale. Those with mild or no preference were disqualified. Participants were randomized into four groups, preference-yes STD-D (n = 48); preference-no STD-D (n = 48); preference-yes LOV-D (n = 35); preference-no LOV-D (n = 45). | No | At 18 months * Preference-yes STD-D; ↓4.8 kg ± 6.1 Preference-yes LOV-D; ↓4.8 kg ± 6.2 Preference-no STD-D; ↓7.9 kg ± 7.8 Preference-no LOV-D; ↓9.4 kg ± 8.1 p = 0.02 difference between preference-yes and preference-no |
| Coles et al. [29] | RCT, over 12 months. Baseline data collected, data obtained every 2 weeks until month 3, then every 6 weeks until 12 months, and 3, 6 and 12 month visits. | 40–75 years BMI > 27 kg/m2 |
144 | 96 (33.3%) |
Participants randomized to ‘Choice’ or ‘No Choice’ groups. ‘No Choice’ group (n = 73) was placed on a set weight loss diet (CSIRO), no change permitted. ‘Choice’ group (n = 71) chose from the CSIRO (n = 34); South Beach (n = 11) or Mediterranean diet (n = 26). | Yes at any time | At 12 months * ‘No Choice’ group; ↓3.5 kg ± 4.5 kg ‘Choice’ group; ↓2.7 kg ± 5 kg p > 0.05 |
| Daby [28] 1 | RCT. Phase I; weekly group meeting for 5 weeks. Phase II; biweekly meetings for 8 weeks and then monthly for 2 months OR weekly phone call. Baseline weight, weight at group meetings, at end of phase 2 and at trial end. | 20–60 years 40%–150% above ideal body weight Females |
82 | 47 (42.7%) |
All participants attended Phase I. Participants then expressed preference for ‘Group’ based or ‘Telephone’ based interventions. Participants were randomized into two groups independent of preference. Four groups resulted, group-yes (n = 24); group-no (n = 23); telephone-yes (n = 10); telephone-no (n = 11). | No | At 33 weeks * Group-yes; ↓15.1 lbs ± 19.3 (6.8 kg ± 9) Group-no; ↓9.7 lbs ± 16.7 (4.4 kg ± 7.6) Telephone-yes; ↓7.6 lbs ± 11.8 (3.4 kg ± 5.4) Telephone-no; ↓9.86 ± 20.2 (4.5 kg ± 9.1) p > 0.05 |
| Fuller [30] 2 | RCT over 10 weeks. Baseline weight was obtained and weekly weights thereafter. | 24–65 years Overweight |
118 | 73 (38.1%) |
Participants randomized to ‘Choice’ or ‘No Choice’ groups. ‘Choice’ group chose between nutrition education (n = 11), behaviour management (n = 22) or exercise (n = 19) for weight loss. ‘No Choice’ were randomly assigned to nutrition education (n = 15); behaviour management (n = 15) or exercise (n = 13) for weight loss. | No | At 10 weeks ‘Choice’ group; ↓4.5 lbs (2 kg) ‘No Choice’ group; ↓7.4 lbs (3.4 kg) p = 0.026 |
| Jolly et al. [31] | RCT over 12 weeks. Baseline data was collected during week 1 and again at 3 months. | ≥18 years BMI ≥ 30 kg/m2 with no obesity related comorbidities or ≥25 kg/m2 if South Asian BMI ≥ 28 kg/m2 with obesity related comorbidities or ≥23 kg/m2 if South Asian. |
740 | 658 (11.1%) |
Participants were randomized to; Weight Watchers (n = 100); Slimming World (n = 100); Rosemary Conley (n = 100); group based, dietetics led program (n = 100); general practice one to one counselling (n = 70); pharmacy led one on one counselling (n = 70); choice of any of the six programs (n = 100) or a comparator group provided with 12 vouchers for a local fitness center. | No | At 3 months ** WW ↓5.2 kg (↓4.2 to ↓6.1) SW ↓4.3 kg (↓3.3 to ↓ 5.2) RC ↓5.3 kg (↓4.2 to ↓6.4) SD ↓3.2 kg (↓2.3 to ↓4.1) GP ↓2.2 kg (↓0.7 to ↓3.7) P ↓2.8 kg (↓1.4 to ↓4.2) Choice ↓3.8 kg (↓2.9 to ↓4.7) Control ↓3 kg (↓1.8 to ↓4.1) p > 0.05 difference between ‘Choice’ and ‘No Choice’ groups |
| Murray et al. [27] | RCT, over 6 months. Baseline data and weekly data was collected for 9 weeks followed by a 3 month and 6 month data collection. | ≥21 years >165 lbs (74.8 kg) Females |
12 | 9 (25%) |
Participants indicated their treatment preference. Patients were independently assigned to follow the self-control method (n = 6) or determination raising (n = 6) method by chance. | No | At 6 month follow-up Preference-yes group; ↓2.8 lbs (1.3 kg) Preference-no group; ↓6.5 lbs (3 kg) p > 0.05 |
| Renjilian et al. [25] | RCT trial over 26 weeks. Baseline data was obtained, and the weekly data collected for 26 weeks. | 21–59 years BMI 28–45 kg/m2 |
75 | 58 (22.7%) |
Participants indicated preference for Individual vs. Group therapy using a 6-point Likert scale, those who had a ‘slight’ preference were excluded from the study. Participants were randomized to one of the two groups. Four groups resulted; Preference-yes group (n = 16); preference-yes individual (n = 13); preference-no group (n = 14); preference-no individual (n = 15). | No | At 26 weeks * Preference-yes group ↓10.9 kg ± 4.06 Preference-no group ↓11.2 kg ± 5.6 Preference-yes individual ↓8.48 kg ± 3 Preference-no individual ↓9.61 kg ± 4.17 p > 0.05 |
| Yancy et al. [24] | Doubly randomised, preference trial over 48 weeks. Baseline data was obtained, every 2 weeks for 24 weeks, then every 4 weeks for 24 weeks. | <75 years BMI ≥ 30 kg/m2 * Participants were veterans |
207 | 175 (15.5%) |
Participants completed a food preference questionnaire. Participants were randomized to a ‘Choice’ or ‘No Choice’ arm. The ‘Choice’ group received information about their food preferences in relation to 2 diet options-low carbohydrate (n = 61) or low-fat (n = 44), before choosing one. The ‘No Choice’ group were randomly assigned to the low-carbohydrate (n = 53) or low–fat (n = 49) diet. | At week 12 | At 48 weeks ** ‘Choice’ arm ↓5.7 kg (↓4.3 to ↓7) ‘No Choice’ arm ↓6.7 kg (↓5.4 to ↓8) Mean difference ↓1.1 kg (↓2.9 to ↓0.8) between groups p = 0.26 |
RCT = Randomised controlled trial, CSIRO = Commonwealth Scientific and Industrial Research Organisation, 1 Unpublished thesis from depository of Vanderbilt University, 2 Unpublished thesis from depository of Michigan State University. * mean ± standard deviation, ** mean (95% confidence interval).