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Dietary carbohydrate restriction augments weight loss-induced improvements in glycaemic control and liver fat in individuals with type 2 diabetes: a randomised controlled trial.
Thomsen, MN, Skytte, MJ, Samkani, A, Carl, MH, Weber, P, Astrup, A, Chabanova, E, Fenger, M, Frystyk, J, Hartmann, B, et al
Diabetologia. 2022;65(3):506-517
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The carbohydrate restricted diet has been shown to be beneficial for Type 2 diabetes (T2D) management and reducing cardiovascular disease risk. This open-label, parallel randomised controlled trial involved Type 2 diabetic patients taking antidiabetic medications who restricted their energy intake by following either a carbohydrate-reduced high protein diet or a conventional diabetic diet. Participants in both groups had a 5.9% reduction in body weight, similar changes in fasting NEFA, apoB, apoA-1, total cholesterol, LDL-cholesterol, HDL-cholesterol, and non-HDL cholesterol, and a significant reduction in fasting glucose, insulin, C-peptide, and HOMA2-IR after 6 weeks of intervention. Carbohydrate-reduced high protein diet group showed a greater reduction in HbA1c and diurnal mean glucose, glycaemic variability, fasting triacylglycerol concentration and liver fat content. Carbohydrate-reduced high protein diet caused an adverse reaction in some patients, and those following a carbohydrate-reduced high protein diet excreted more urea than those eating a conventional diabetic diet. To confirm the results of this study, long-term robust studies are needed. This study can assist healthcare professionals in understanding the benefits of following a carbohydrate-reduced high protein diet in improving glycaemic control, triglyceride levels, and reducing body weight in Type 2 diabetes patients.
Abstract
AIMS/HYPOTHESIS Lifestyle modification and weight loss are cornerstones of type 2 diabetes management. However, carbohydrate restriction may have weight-independent beneficial effects on glycaemic control. This has been difficult to demonstrate because low-carbohydrate diets readily decrease body weight. We hypothesised that carbohydrate restriction enhances the beneficial metabolic effects of weight loss in type 2 diabetes. METHODS This open-label, parallel RCT included adults with type 2 diabetes, HbA1c 48-97 mmol/mol (6.5-11%), BMI >25 kg/m2, eGFR >30 ml min-1 [1.73 m]-2 and glucose-lowering therapy restricted to metformin or dipeptidyl peptidase-4 inhibitors. Participants were randomised by a third party and assigned to 6 weeks of energy restriction (all foods were provided) aiming at ~6% weight loss with either a carbohydrate-reduced high-protein diet (CRHP, percentage of total energy intake [E%]: CH30/P30/F40) or a conventional diabetes diet (CD, E%: CH50/P17/F33). Fasting blood samples, continuous glucose monitoring and magnetic resonance spectroscopy were used to assess glycaemic control, lipid metabolism and intrahepatic fat. Change in HbA1c was the primary outcome; changes in circulating and intrahepatic triacylglycerol were secondary outcomes. Data were collected at Copenhagen University Hospital (Bispebjerg and Herlev). RESULTS Seventy-two adults (CD 36, CRHP 36, all white, 38 male sex) with type 2 diabetes (mean duration 8 years, mean HbA1c 57 mmol/mol [7.4%]) and mean BMI of 33 kg/m2 were enrolled, of which 67 (CD 33, CRHP 34) completed the study. Body weight decreased by 5.8 kg (5.9%) in both groups after 6 weeks. Compared with the CD diet, the CRHP diet further reduced HbA1c (mean [95% CI] -1.9 [-3.5, -0.3] mmol/mol [-0.18 (-0.32, -0.03)%], p = 0.018) and diurnal mean glucose (mean [95% CI] -0.8 [-1.2, -0.4] mmol/l, p < 0.001), stabilised glucose excursions by reducing glucose CV (mean [95% CI] -4.1 [-5.9, -2.2]%, p < 0.001), and augmented the reductions in fasting triacylglycerol concentration (by mean [95% CI] -18 [-29, -6]%, p < 0.01) and liver fat content (by mean [95% CI] -26 [-45, 0]%, p = 0.051). However, pancreatic fat content was decreased to a lesser extent by the CRHP than the CD diet (mean [95% CI] 33 [7, 65]%, p = 0.010). Fasting glucose, insulin, HOMA2-IR and cholesterol concentrations (total, LDL and HDL) were reduced significantly and similarly by both diets. CONCLUSIONS/INTERPRETATION Moderate carbohydrate restriction for 6 weeks modestly improved glycaemic control, and decreased circulating and intrahepatic triacylglycerol levels beyond the effects of weight loss itself compared with a CD diet in individuals with type 2 diabetes. Concurrent differences in protein and fat intakes, and the quality of dietary macronutrients, may have contributed to these results and should be explored in future studies. TRIAL REGISTRATION ClinicalTrials.gov NCT03814694. FUNDING The study was funded by Arla Foods amba, The Danish Dairy Research Foundation, and Copenhagen University Hospital Bispebjerg Frederiksberg.
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Diets with high or low protein content and glycemic index for weight-loss maintenance.
Larsen, TM, Dalskov, SM, van Baak, M, Jebb, SA, Papadaki, A, Pfeiffer, AF, Martinez, JA, Handjieva-Darlenska, T, Kunešová, M, Pihlsgård, M, et al
The New England journal of medicine. 2010;363(22):2102-13
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The recommended diet composition for best preventing and managing obesity has remained inconclusive. The aim of this trial is to test the efficacy of moderate fat diets that vary in protein content and glycaemic index for preventing weight regain after weight loss. After completing an 8-week low calorie diet, participants were assigned to a low protein and low-glycaemic-index diet, a low-protein and high-glycaemic-index diet, a high-protein and low-glycaemic index diet, a high-protein and high-glycaemic-index diet or a control diet. A total of 548 participants adhered to and completed the 26-week intervention following the 8-week intensive weight loss programme. This study found that participants assigned to the high-protein and low-glycaemic index diet maintained the initial weight loss and had a higher rate of completion compared with the other diets. The authors conclude that this diet composition appears to be ideal for prevention of weight regain in obese patients following successful weight loss.
Abstract
BACKGROUND Studies of weight-control diets that are high in protein or low in glycemic index have reached varied conclusions, probably owing to the fact that the studies had insufficient power. METHODS We enrolled overweight adults from eight European countries who had lost at least 8% of their initial body weight with a 3.3-MJ (800-kcal) low-calorie diet. Participants were randomly assigned, in a two-by-two factorial design, to one of five ad libitum diets to prevent weight regain over a 26-week period: a low-protein and low-glycemic-index diet, a low-protein and high-glycemic-index diet, a high-protein and low-glycemic-index diet, a high-protein and high-glycemic-index diet, or a control diet. RESULTS A total of 1209 adults were screened (mean age, 41 years; body-mass index [the weight in kilograms divided by the square of the height in meters], 34), of whom 938 entered the low-calorie-diet phase of the study. A total of 773 participants who completed that phase were randomly assigned to one of the five maintenance diets; 548 completed the intervention (71%). Fewer participants in the high-protein and the low-glycemic-index groups than in the low-protein-high-glycemic-index group dropped out of the study (26.4% and 25.6%, respectively, vs. 37.4%; P=0.02 and P=0.01 for the respective comparisons). The mean initial weight loss with the low-calorie diet was 11.0 kg. In the analysis of participants who completed the study, only the low-protein-high-glycemic-index diet was associated with subsequent significant weight regain (1.67 kg; 95% confidence interval [CI], 0.48 to 2.87). In an intention-to-treat analysis, the weight regain was 0.93 kg less (95% CI, 0.31 to 1.55) in the groups assigned to a high-protein diet than in those assigned to a low-protein diet (P=0.003) and 0.95 kg less (95% CI, 0.33 to 1.57) in the groups assigned to a low-glycemic-index diet than in those assigned to a high-glycemic-index diet (P=0.003). The analysis involving participants who completed the intervention produced similar results. The groups did not differ significantly with respect to diet-related adverse events. CONCLUSIONS In this large European study, a modest increase in protein content and a modest reduction in the glycemic index led to an improvement in study completion and maintenance of weight loss. (Funded by the European Commission; ClinicalTrials.gov number, NCT00390637.).