Layman 2009.

Study characteristics
Methods	Review comparison(s) addressed by this study: 1 Study design: RCT, parallel, multi‐centre (2) Trial registry number: NR Total number of trial arms: 2 Year trial started: NR Sample size calculation: Yes Outcome(s) used for sample size calculation: Change in fat mass (FM) Duration of run‐in period (weeks): 2.86 What was the duration of the weight loss phase: 12 months What was the duration of the weight maintenance phase: NA Other notes about methods: Run‐in period was 10‐20 days and participants were instructed to eat as they had been the 6 months prior.
Participants	Country and setting: USA, outpatient research at universities in Urbana‐Champaign and Pennsylvania Eligibility criteria: Inclusion criteria NR. Participants were excluded if they had a BMI < 26 kg/m2 or weight > 140 kg; were smokers; had any existing medical condition requiring medication which may affect outcomes, such as lipid‐lowering medications, oral steroids or antidepressants. Type 2 diabetes at baseline: Unclear; stratified with non‐T2DM since no relevant information was reported or could be obtained. Impaired glucose tolerance at baseline: Unclear Cardiovascular conditions/risk factors/events at baseline: No Gender: Mixed Total number randomised: 130 Total attrition in trial: 59 Treatment diet Participants randomised: 64 Participants withdrawn (voluntary): 23 Total attrition: 23 Control diet: Participants randomised: 66 Participants withdrawn (voluntary): 36 Total attrition: 36 Baseline data treatment diet: Randomised participants not included: None Age (years): mean (SE) 45.2 (1.2) Gender distribution (as reported): female 36/64 (56.3%), male 28/64 (43.7%) Weight (kg): mean (SE) 91.7 (2.0) BMI (kg/m2): mean (SE) 32.2 (0.5) 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 (SE) 46.0 (1.0) Gender distribution (as reported): female 35/66 (53.0%), male 31/66 (47.0%) Weight (kg): mean (SE) 93.8 (1.6) BMI (kg/m2): mean (SE) 32.7 (0.5) 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: PRO diet. Prescribed dietary protein at 1.6 g/kg/d (~30% of energy intake) with a carbohydrate/protein ratio < 1.5 and dietary lipids ~30% energy intake. Recommendation for 30 min of walking 5 d/week. Energy prescription of 7100 kJ/d for women and 7940 kJ/d for men Treatment diet type (carbohydrate‐fat‐protein): Low‐balanced‐high Exercise component? Yes Recipients: N = 64 in total of which N = 28 males (44%) and N = 36 females (56%), mean (SE) age 45.2 (1.2) years, mean (SE) weight 91.7 (2.0) kg, mean (SE) BMI 32.2 (0.5) kg/m2 Why? Increased protein and reduced carbohydrate diets are often effective, for short‐term weight loss. This study investigated the longer‐term benefits of a high‐protein diet while adding a comprehensive nutrition education and a high level of monitoring. We anticipated that regardless of the compliance definition, the PRO diet would invoke more favourable body composition and blood lipid changes both after active weight loss and through the 12‐mo weight loss and maintenance periods. What (materials)? "Each diet group received a menu plan with meals for each day meeting established nutritional requirements and dietary fat guidelines. Participants were provided with electronic food scales and were instructed to weigh all food servings at all meals. Participants received specific diet programme instructions from a research dietitian, including the menus, food substitutions, and portion sizes. Physical activity was monitored using daily activity logs and armband accelerometers (BodyMedia) worn 3 d/mo. Activity logs were collected each week." What (procedures)? High‐protein, low‐carbohydrate diet with comprehensive nutrition education and high levels of monitoring. The PRO diet provided dietary protein at 1.6 g/kg/day (30% of energy intake) with a carbohydrate:protein ratio < 1.5 and dietary lipids roughly 30% energy intake. These diets were designed to fall within the Acceptable Macronutrient Distribution Range (AMDR) of the DRI as established by the Institute of Medicine with minimum Recommended Daily Allowance (RDA) intakes for carbohydrates > 130 g/d and protein > 0.8 g/kg/d and with upper ranges for carbohydrates, 65% and protein, 35% of total energy intake. The 2 diets were formulated to be equal in energy [7.10 MJ/d (1700 kcal/d for females; 7.94 MJ/d (1900/d kcal) for males], total fat intake (30% of energy), and fibre (17 g/4.18 MJ). For the PRO group, the education guidelines emphasised use of high‐quality, low‐fat proteins including lean meats, reduced‐fat dairy, and eggs or egg substitutes. Both diets included 5 vegetable servings/d and 2–3 fruit servings/d. With weekly sessions (60 mins) led by a dietitian. The exercise guidelines emphasised physical activity lifestyle recommendations based on the NIH Guidelines for Weight Management. These guidelines recommend a minimum of 30 min of walking 5 d/wk; however, participation was voluntary. Who provided? Dietitian How and where? Face‐to‐face at the weight management research facility When and how much? Throughout the 12‐mo study, participants were required to attend a 1‐h meeting each week. Strategies to improve or maintain fidelity; tailoring and modification: Group meeting with the research dietitians who provided diet information, answered questions, and reviewed diet records for treatment compliance. Participants were required to report 2 3‐d weighed food records during the baseline period prior to assignment to diet groups. Nutrient intakes were evaluated as mean daily intakes from the 3‐d weighed records using Nutritionist Pro software (First DataBank) for treatment compliance. Compliance with dietary protocols was also monitored with plasma TAG at 0, 4,and 12 mo as a marker of carbohydrate intake and 24‐h urinary urea at 0, 4, and 8 mo as a marker of protein intake. High degree of nutrition monitoring throughout the 12 months with weekly meetings that included monitoring body weight, weighed food records, and diet instruction. 3‐d weighed food records, which were reviewed each week with feedback to participants about diet compliance. Any participant with an unexcused absence at a weekly meeting was called by a staff dietitian to promote attendance and any participant with 3 consecutive absences was asked to define their participation status in the study. Extent of intervention fidelity: All participants completing data collection participated in < 75% of meetings, including weigh‐ins and diet records. Compliance with dietary protocols was also monitored with plasma TAG at 0, 4, and 12 mo as a marker of carbohydrate intake and 24‐h urinary urea at 0, 4, and 8 mo as a marker of protein intake. Concomitant interventions: Participants were excluded if they were on lipid‐lowering medications, oral steroids or antidepression medication. Control diet: Name (as reported) and brief description: CARB diet. Provided dietary protein equal to 0.8 g/kg/d (~15% of energy intake) with a carbohydrate/protein ratio > 3.5 and total fat ~30% of energy intake. Recommendation for 30 min of walking 5 d/week. Energy prescription of 7100 kJ/d for women and 7940 kJ/d for men Control diet type (carbohydrate‐fat‐protein): Balanced‐balanced‐balanced Exercise component? Yes Recipients: N = 66 in total of which N = 31 males (47%) and N = 35 females (53%), mean (SE) age 46.0 (1.0) years, mean (SE) weight 93.8 (1.6) kg, mean (SE) BMI 32.7 (0.5) kg/m2. Why? NR What (materials)? "Each diet group received a menu plan with meals for each day meeting established nutritional requirements and dietary fat guidelines. Participants were provided with electronic food scales and were instructed to weigh all food servings at all meals. Participants received specific diet program instructions from a research dietitian, including the menus, food substitutions, and portion sizes. Physical activity was monitored using daily activity logs and armband accelerometers (BodyMedia) worn 3 d/mo. Activity logs were collected each week." What (procedures)? The CHO diet provided dietary protein equal to 0.8 g/kg/d (15% of energy intake) with a carbohydrate:protein ratio > 3.2 and total fat roughly 30% of energy intake. High‐carbohydrate, low‐protein, low‐fat diet with comprehensive nutrition education and high levels of monitoring with weekly sessions (60 mins) led by a dietitian. These diets were designed to fall within the Acceptable Macronutrient Distribution Range (AMDR) of the DRI as established by the Institute of Medicine with minimum Recommended Daily Allowance (RDA) intakes for carbohydrates > 130 g/d and protein > 0.8 g/kg/d and with upper ranges for carbohydrates, 65% and protein, 35% of total energy intake. The 2 diets were formulated to be equal in energy [7.10 MJ/d (1700 kcal/d for females; 7.94 MJ/d (1900/d kcal) for males], total fat intake (30% of energy), and fibre (17 g/4.18 MJ). The education guidelines for the CHO group followed the USDA Food Guide Pyramid (19) and emphasised restricting dietary fat and cholesterol with use of whole‐grain breads, rice, cereals, and pasta. Both diets included 5 vegetable servings/d and 2–3 fruit servings/d. The exercise guidelines emphasised physical activity lifestyle recommendations based on the NIH Guidelines for Weight Management. These guidelines recommend a minimum of 30 min of walking 5 d/wk; however, participation was voluntary. Who provided? Dietitian How and where? Face‐to‐face at the weight management research facility When and how much? Throughout the 12‐mo study, participants were required to attend a 1‐h meeting each week. Strategies to improve or maintain fidelity; tailoring and modification: Group meeting with the research dietitians who provided diet information, answered questions, and reviewed diet records for treatment compliance. Participants were required to report 2 3‐d weighed food records during the baseline period prior to assignment to diet groups. Nutrient intakes were evaluated as mean daily intakes from the 3‐d weighed records using Nutritionist Pro software (First DataBank) for treatment compliance. Compliance with dietary protocols was also monitored with plasma TAG at 0, 4,and 12 mo as a marker of carbohydrate intake and 24‐h urinary urea at 0, 4, and 8 mo as a marker of protein intake. High degree of nutrition monitoring throughout the 12 months with weekly meetings that included monitoring body weight, weighed food records, and diet instruction, 3‐d weighed food records, which were reviewed each week with feedback to participants about diet compliance. Any participant with an unexcused absence at a weekly meeting was called by a staff dietitian to promote attendance and any participant with 3 consecutive absences was asked to define their participation status in the study. Extent of intervention fidelity: All participants completing data collection participated in < 75% of meetings, including weigh‐ins and diet records. Compliance with dietary protocols was also monitored with plasma TAG at 0, 4, and 12 mo as a marker of carbohydrate intake and 24‐h urinary urea at 0, 4, and 8 mo as a marker of protein intake. Concomitant interventions: Participants were excluded if they were on lipid‐lowering medications, oral steroids or antidepression medication.
Outcomes	Change in body weight (kg) at 3 to < 12 months: Yes Change in body weight (kg) at ≥ 12 months: Yes 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: Yes Change in HDL (mmol/L) at ≥ 12 months: Yes 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: Yes Participant‐reported adverse effects: No
Notes	Number and type of records(s): journal article Trial acronym/name: None Trial funded by: National Cattlemen's Beef Association, Beef Checkoff and Kraft Foods Declaration of interest: "D. K. Layman serves on Speakers Bureau for National Cattlemen’s Beef Association. E. M. Evans, D. Erickson, J. Seyler, J. Weber, D. Bagshaw, A. Griel, T. Psota, and P. Kris‐Etherton, no conflicts of interest." Author contacted, but requested information not provided.