Ooi 2021.

Study characteristics
Methods	Review comparison(s) addressed by this study: 1 Study design: RCT, parallel, single‐centre (1) Trial registry number: NR Total number of trial arms: 3 Year trial started: NR Sample size calculation: Yes Outcome(s) used for sample size calculation: Lean mass and HOMA‐IR Duration of run‐in period (weeks): NA What was the duration of the weight loss phase: 16 weeks What was the duration of the weight maintenance phase: 8 weeks Other notes about methods: NA
Participants	Country and setting: Singapore, outpatient research centre. Prescribed meals were provided and delivered to the homes of participants during the weight loss phase. Eligibility criteria: Chinese men and women aged 21 to 45 years who are classed as overweight or obese (BMI 25 to 36 kg/m2) and with a body fat percentage of ≥ 25%. No explicit exclusion criteria are reported, but the authors reported that none of the participants had existing medical conditions and only engaged in low to moderate physical activity Type 2 diabetes at baseline: No Impaired glucose tolerance at baseline: Unclear Cardiovascular conditions/risk factors/events at baseline: No Gender: Mixed Total number randomised: 132 Total attrition in trial: 24 Treatment diet Participants randomised: 43 Participants withdrawn (voluntary): 2 Total attrition: 4 Control diet: Participants randomised: 44 Participants withdrawn (voluntary): 4 Total attrition: 8 Baseline data treatment diet: Randomised participants not included: None Age (years): mean (SD) 32.0 (6.82) Gender distribution (as reported): female 21/43 (49%), male 22/43 (51%) Weight (kg): mean (SD) 81.8 (12.59) BMI (kg/m2): mean (SD) 29.6 (3.02) DBP (mmHg): NR SBP (mmHg): NR HbA1c (%): NR LDL (mmol/L): NR HDL (mmol/L): NR Non‐HDL (mmol/L): NR TC (mmol/L): NR TG (mmol/L): NR Baseline data control diet: Randomised participants not included: None Age (years): mean (SD) 33.5 (7.89) Gender distribution (as reported): female 24/44 (55%), male 20/44 (45%) Weight (kg): mean (SD) 80.1 (10.61) BMI (kg/m2): mean (SD) 29.3 (2.39) DBP (mmHg): NR SBP (mmHg): NR HbA1c (%): NR LDL (mmol/L): NR HDL (mmol/L): NR Non‐HDL (mmol/L): NR TC (mmol/L): NR TG (mmol/L): NR Group differences at baseline: No Characteristic(s) with significant group difference and relevant statistic: NA Other notes about participants: NA
Interventions	Energy (E) comparison of treatment vs control diets: Similar energy prescription/approach to restrict energy intake in both diets Treatment diet: Name (as reported) and brief description: High‐protein diet with placebo supplementation (HP) prescribing 27% protein, 43% carbohydrates and 30% fat. Energy deficit of 500 kcal per day Treatment diet type (carbohydrate‐fat‐protein): Low‐balanced‐high Exercise component? No Recipients: N = 21 women and N = 22 men with mean (SD) age 32.0 (6.82) years, mean (SD) weight 81.8 (12.59) kg, mean (SD) BMI 29.6 (3.02) kg/m2, none had existing diabetes or hypertension and all had normal renal, liver and thyroid function. Why? The diet was included as a comparator for a standard‐protein diet with branched‐chain amino acids (BCAAs) supplementation. High‐protein diets are stated as reducing the loss of lean mass during weight loss, but they are expensive. What (materials)? Participants were prescribed a hypocaloric diet with a deficit of 500 kcal per day. "To encourage compliance, subjects had prescribed meals provided and delivered to their homes weekly..." "Weekly food delivery for a 6‐d food supply was provided for the first 4 wk. Subjects had 1 “free day” each week of their own food. For the subsequent 12 wk, only lunch and dinner meals and snacks were provided for 6 d per wk." Participants were also provided with food checklists with their weekly food delivery, to check off food and record additional food and beverages they consumed. Accelerometers were provided to participants at week 0 and week 8 visits. What (procedures)? The high‐protein diet consisted of 16 weeks following a diet with a macronutrient composition of 30% fat, 43% carbohydrate and 27% protein; with placebo supplementation (as opposed to BCAAs). Diet counselling sessions were provided and participants were called to assess and encourage compliance. Who provided? A dietitian provided the counselling sessions and called participants. How and where? Face‐to‐face counselling sessions were provided; the location of sessions, and whether these were group or individual sessions, was not reported. Participants were called to improve compliance. When and how much? Counselling sessions were provided at visits at 0, 4, 8, 12 and 16 weeks; duration of sessions was not reported. Participants were called on a fortnightly basis; duration not reported. Strategies to improve or maintain fidelity; tailoring and modification: Prescribed meals were provided and delivered to encourage compliance, food checklists were used to document dietary compliance, counselling sessions and regular phone calls from the dietitian were used to assess and encourage compliance. Where certain foods could not be consumed by a participant, the dietitian would substitute with foods of a similar composition to adhere to prescribed energy and macronutrients. Extent of intervention fidelity: Urinary urea:creatinine ratio was used as a surrogate for protein intake and dietary compliance. This increased in the treatment group during the weight loss phase, indicating compliance. Food checklists showed modest deviations from dietary prescription, indicating acceptable compliance. Concomitant interventions: NR Control diet: Name (as reported) and brief description: Standard‐protein diet with placebo supplementation (control, CT) prescribing 14% protein, 56% carbohydrates and 30% fat. Energy deficit of 500 kcal per day Control diet type (carbohydrate‐fat‐protein): Balanced‐balanced‐balanced Exercise component? No Recipients: N = 24 women and N = 20 men with mean (SD) age 33.5 (7.89) years, mean (SD) weight 80.1 (10.61) kg, mean (SD) BMI 29.3 (2.39) kg/m2, none had existing diabetes or hypertension and all had normal renal, liver and thyroid function. Why? The diet was included as a control for an identical diet with branched‐chain amino acids (BCAAs) supplementation. The latter is hypothesised to improve lean mass preservation over a standard‐protein diet without supplementation. What (materials)? Participants were prescribed a hypocaloric diet with a deficit of 500 kcal per day. "To encourage compliance, subjects had prescribed meals provided and delivered to their homes weekly..." "Weekly food delivery for a 6‐d food supply was provided for the first 4 wk. Subjects had 1 “free day” each week of their own food. For the subsequent 12 wk, only lunch and dinner meals and snacks were provided for 6 d per wk." Participants were also provided with food checklists with their weekly food delivery. What (procedures)? The standard‐protein diet consisted of 16 weeks following a diet with a macronutrient composition of 30% fat, 56% carbohydrate and 14% protein; with placebo supplementation (as opposed to BCAAs). Diet counselling sessions were provided and participants were called to assess and encourage compliance. Who provided? A dietitian provided the counselling sessions and called participants. How and where? Face‐to‐face counselling sessions were provided; the location of sessions, and whether these were group or individual sessions, was not reported. Participants were called to improve compliance. When and how much? Counselling sessions were provided at visits at 0, 4, 8, 12 and 16 weeks; duration of sessions was not reported. Participants were called on a fortnightly basis; duration not reported. Strategies to improve or maintain fidelity; tailoring and modification: Prescribed meals were provided and delivered to encourage compliance, food checklists were used to document dietary compliance, counselling sessions and regular phone calls from the dietitian were used to assess and encourage compliance. Where certain foods could not be consumed by a participant, the dietitian would substitute with foods of a similar composition to adhere to prescribed energy and macronutrients. Extent of intervention fidelity: Urinary urea:creatinine ratio was used as a surrogate for protein intake and dietary compliance. This decreased in the control group during the weight loss phase, indicating compliance. Food checklists showed modest deviations from dietary prescription, indicating acceptable compliance. Concomitant interventions: NR
Outcomes	Change in body weight (kg) at 3 to < 12 months: Yes Change in body weight (kg) at ≥ 12 months: No Number of participants with 5% weight loss from baseline at 3 to < 12 months: No Number of participants with 5% weight loss from baseline at ≥ 12 months: No Change in BMI (kg/m2) at 3 to 12 months: No Change in BMI (kg/m2) at ≥ 12 months: No Number of participants with 5% BMI reduction from baseline at 3 to 12 months: No Number of participants with 5% BMI reduction from baseline at ≥ 12 months: No Change in DBP (mmHg) at ≥ 12 months: No Change in SBP (mmHg) at ≥ 12 months: No All‐cause mortality at ≥ 12 months: No Cardiovascular mortality at ≥ 12 months: No Non‐fatal myocardial infarction at ≥ 12 months: No Non‐fatal stroke at ≥ 12 months: No Diagnosis of type 2 diabetes mellitus at ≥ 12 months: No Change in HbA1c (%) at ≥ 12 months: No Change in LDL (mmol/L) at ≥ 12 months: No Change in HDL (mmol/L) at ≥ 12 months: No Change in non‐HDL (mmom/L) at ≥ 12 months: No Change in total cholesterol (TC) (mmol/L) at ≥ 12 months: No Change in triglycerides (or triacylglycerides) (TG) (mmol/L) at ≥ 12 months: No Participant‐reported adverse effects: No
Notes	Number and type of records(s): journal article Trial acronym/name: None Trial funded by: Clinical Scientist‐Individual Research Grant administered by Ministry of Health’s National Medical Research Council (NMRC), Singapore‐ NMRC/CIRG/1375/2013, and the Singapore Institute for Clinical Sciences, Agency for Science Technology and Research (A∗STAR), Singapore Declaration of interest: "The authors report no conflicts of interest."