Comparison of two low-fat diets, differing in protein and carbohydrate, on psychological wellbeing in adults with obesity and type 2 diabetes: a randomised clinical trial.

BACKGROUND: Although higher-protein diets (HP) can assist with weight loss and glycemic control, their effect on psychological wellbeing has not been established. The objective of this study was to compare the effects of a HP and a higher-carbohydrate diet (HC), combined with regular exercise, on psychological wellbeing both during weight loss (WL) and weight maintenance phases (WM). METHODS: In a parallel RCT, 61 adults with T2D (mean ± SD: BMI 34.3 ± 5.1 kg/m2, aged 55 ± 8 years) consumed a HP diet (29% protein, 34% carbohydrate, 31% fat) or an isocaloric HC diet (21%:48%:24%), with moderate intensity exercise, for 12 weeks of WL and 12 weeks of WM. Secondary data evaluating psychological wellbeing was assessed using: Problems Areas in Diabetes (PAID); Diabetes-39 Quality of Life (D-39); Short Form Health Survey (SF-36); Perceived Stress Scale-10 (PSS-10) and the Leeds Sleep Evaluation Questionnaire (LSEQ) at Weeks 0, 12 and 24 and evaluated with mixed models analysis. RESULTS: Independent of diet, improvements for PAID; D-39 diabetes control; D-39 severity of diabetes; SF-36 physical functioning and SF-36 general health were found following WL (d = 0.30 to 0.69, P ≤ 0.04 for all) which remained after 12 weeks of WM. SF-36 vitality improved more in the HP group (group x time interaction P = 0.03). Associations were seen between HbA1c and D-39 severity of diabetes rating (r = 0.30, P = 0.01) and SF-36 mental health (r = - 0.32, P = 0.003) and between weight loss and PAID (r = 0.30, P = 0.01). CONCLUSION: Several improvements in diabetes-related and general psychological wellbeing were seen similarly for both diets following weight loss and a reduction in HbA1c with most of these improvements remaining when weight loss was sustained for 12 weeks. A HP diet may provide additional increases in vitality. TRIAL REGISTRATION: The trial was prospectively registered with the Australian New Zealand Clinical Trials Registry (ACTRN 12613000008729 ) on 4 January 2013.

A randomised trial comparing low-fat diets differing in carbohydrate and protein ratio, combined with regular moderate intensity exercise, on glycaemic control, cardiometabolic risk factors, food cravings, cognitive function and psychological wellbeing in adults with type 2 diabetes: Study protocol.

BACKGROUND: Hypocaloric low-fat diets, high in protein with moderate carbohydrate (HP) can enhance weight loss, improve glycaemic control and improve cardiometabolic health risk factors in type 2 diabetes mellitus (T2DM). However, it is unclear whether the metabolic benefits observed during weight loss are sustained during energy-balance and weight maintenance. Furthermore, there is a lack of evidence regarding the effect of HP diets on food cravings, cognitive function and psychological wellbeing in T2DM, despite carbohydrate food cravings, cognitive impairment and depression being associated with hyperglycaemia. METHODS/DESIGN: Overweight/obese adults with T2DM were randomised to consume either a HP diet (n=32, ~32% protein, 33% carbohydrate, 30% fat) or a higher-carbohydrate diet (HC, n=29, ~22% protein, 51% carbohydrate, 22% fat) for 24 weeks with 30 min of moderate intensity exercise five days/week for the study duration. There were 2 phases: a 12 week weight loss phase followed by a 12 week weight maintenance phase. Primary outcome was glycaemic control (glycosylated haemoglobin; HbA1c). Secondary outcomes were cardiometabolic risk factors (body composition, fasting blood pressure, blood lipids, glucose, insulin and C-reactive protein), food cravings, cognitive function (memory; psychomotor and executive function and psychological well-being. Outcomes were measured at baseline and the end of each 12-week intervention phase. Data will be analysed as intention-to-treat using linear mixed effects models. CONCLUSION: This study will examine the effects of two dietary interventions on health outcomes in T2DM during weight loss and notably following weight maintenance where there is a paucity of evidence.

Weight loss on a structured hypocaloric diet with or without exercise improves emotional distress and quality of life in overweight and obese patients with type 2 diabetes.

AIMS/INTRODUCTION: To evaluate the effects of a caloric restricted weight loss program with or without supervised resistance exercise training (EX) on diabetes-related emotional distress and quality of life (QOL) in overweight and obese patients with type 2 diabetes. MATERIALS AND METHODS: In a parallel design, 106 men and women with type 2 diabetes were randomized to a prescriptive 16-week caloric restricted diet (D; 6,000-7,000 kJ/day), with (n = 65) or without (n = 41) EX (three times per week). Bodyweight, glycated hemoglobin, diabetes-specific emotional distress (Problem Areas in Diabetes [PAID] questionnaire) and QOL (Diabetes-39 [D-39] questionnaire) was assessed pre- and post-intervention. RESULTS: A total of 84 participants completed the study (D n = 33, D + EX n = 51). Weight loss was significantly greater in D + EX compared with D (-11.4 ± 5.8 vs -8.8 ± 5.8 kg, P = 0.04 time × diet). Overall, there were significant improvements in glycated hemoglobin, PAID total score and the D-39 dimensions of 'diabetes control', 'anxiety and worry', 'sexual functioning', 'energy and mobility', 'overall rating of QOL' and 'severity of diabetes' (P ≤ 0.01 for time). The D-39 dimension, 'social burden', did not change (P = 0.07 for time). There was no difference between groups in the response for any of these variables (P ≥ 0.10). CONCLUSION: A structured caloric restricted diet with or without EX improves emotional distress and QOL in overweight and obese patients with type 2 diabetes. This trial was registered with Australian New Zealand Clinical Trials Registry (http://www.anzctr.org.au; ACTR No: ACTRN12608000206325).

Oral bovine colostrum supplementation enhances buffer capacity but not rowing performance in elite female rowers.

A randomized, double-blind, placebo controlled design was used in which 13 elite female rowers, all of whom had competed at World Championships, were supplemented with 60 g day-1 of either bovine colostrum (BC; n = 6) or concentrated whey protein powder (WP; n = 7) during 9 weeks of pre-competition training. All subjects undertook the study as a group and completed the same training program. Prior to, and after 9 weeks of supplementation and training, subjects completed an incremental rowing test (ROW1) on a rowing ergometer consisting of 3 3 4-min submaximal workloads and a 4-min maximal effort (4 max), each separated by a 1-min recovery period. The rowing test was repeated after a 15-min period of passive recovery (ROW2). The 4 max for ROW1 provided a measure of performance, and the difference between the 4 max efforts of ROW1 and ROW2 provided an index of recovery. Blood lactate concentrations and pH measured prior to exercise and at the end of each workload were used to estimate blood buffer capacity (beta). Food intake was recorded daily for dietary analysis. There were no differences in macronutrient intakes (p >.56) or training volumes (p >.99) between BC and WP during the study period. Rowing performance (distance rowed and work done) during 4 max of ROW2 was less than ROW1 at baseline (p <.05) but not different between groups (p >.05). Performance increased in both rows by Week 9 (p <.001), with no difference between groups (p >.75). However, the increase was greatest in ROW2 (p <.05), such that by Week 9 there was no longer a difference in performance between the two rows in either group (p >.05). b was not different between groups for ROW1 at baseline (BC 38.3 5.0, WP 38.2 7.2 slykes; p >.05) but was higher in BC by Week 9 (BC 40.8 5.9, WP 33.4 5.3 slykes; p <.05). b for ROW2 followed the same pattern of change as for ROW1. We conclude that supplementation with BC improves b, but not performance, in elite female rowers. It was not possible to determine whether b had any effect on recovery.