SummaryThere are few studies comparing the effects of low-carbohydrate/high-protein diets with low-fat/high-carbohydrate diets for obesity and cardiovascular disease risk. This systematic review focuses on randomized controlled trials of lowcarbohydrate diets compared with low-fat/low-calorie diets. Studies conducted in adult populations with mean or median body mass index of Ն28 kg m -2 were included. Thirteen electronic databases were searched and randomized controlled trials from January 2000 to March 2007 were evaluated. Trials were included if they lasted at least 6 months and assessed the weight-loss effects of lowcarbohydrate diets against low-fat/low-calorie diets. For each study, data were abstracted and checked by two researchers prior to electronic data entry. The computer program Review Manager 4.2.2 was used for the data analysis. Thirteen articles met the inclusion criteria. There were significant differences between the groups for weight, high-density lipoprotein cholesterol, triacylglycerols and systolic blood pressure, favouring the low-carbohydrate diet. There was a higher attrition rate in the low-fat compared with the low-carbohydrate groups suggesting a patient preference for a low-carbohydrate/high-protein approach as opposed to the Public Health preference of a low-fat/high-carbohydrate diet. Evidence from this systematic review demonstrates that low-carbohydrate/high-protein diets are more effective at 6 months and are as effective, if not more, as low-fat diets in reducing weight and cardiovascular disease risk up to 1 year. More evidence and longer-term studies are needed to assess the long-term cardiovascular benefits from the weight loss achieved using these diets.

ObjectivesTo evaluate effectiveness of a structured one-to-one behaviour change programme on weight loss in obese and overweight individuals.DesignRandomised controlled trial.Setting23 general practices in Camden, London.Participants381 adults with body mass index ≥25 kg/m2 randomly assigned to intervention (n=191) or control (n=190) group.InterventionsA structured one-to-one programme, delivered over 14 visits during 12 months by trained advisors in three primary care centres compared with usual care in general practice.Outcome measuresChanges in weight, per cent body fat, waist circumference, blood pressure and heart rate between baseline and 12 months.Results217/381 (57.0%) participants were assessed at 12 months: missing values were imputed. The difference in mean weight change between the intervention and control groups was not statistically significant (0.70 kg (0.67 to 2.17, p=0.35)), although a higher proportion of the intervention group (32.7%) than the control group (20.4%) lost 5% or more of their baseline weight (OR: 1.80 (1.02 to 3.18, p=0.04)). The intervention group achieved a lower mean heart rate (mean difference 3.68 beats per minute (0.31 to 7.04, p=0.03)) than the control group. Participants in the intervention group reported higher satisfaction and more positive experiences of their care compared with the control group.ConclusionsAlthough there is no significant difference in mean weight loss between the intervention and control groups, trained non-specialist advisors can deliver a structured programme and achieve clinically beneficial weight loss in some patients in primary care. The intervention group also reported a higher level of satisfaction with the support received. Primary care interventions are unlikely to be sufficient to tackle the obesity epidemic and effective population-wide measures are also necessary.Clinical trial registration numberTrial registrationClincaltrials.gov NCT00891943.

Background:  With the current obesity epidemic, the search for effective weight loss approaches is required. In the present study, changes in weight, body composition and cardiovascular (CV) risk in response to a low‐fat, reduced‐energy diet (LFRE), a low‐carbohydrate/high‐protein diet (LCHP), or a commercially available very low‐calorie diet (LighterLife; LL) were assessed. Methods:  One hundred and twenty obese patients (body mass index ≥35 kg/m2) underwent a screening period of 3 months on the LFRE. Those who lost >5% of their body weight were maintained on this approach for an additional 3 months, whereas those who lost >10% at this time were maintained for 1 year. Patients failing to achieve these targets were randomly allocated to either the LCHP (n = 38) or LL (n = 34) for a period of 9 months. Results:  Significantly greater weight loss was seen for patients on the LL than the LCHP at 3 (mean (±SD) −11.6 ± 12.9 vs −2.8 ± 4.5 kg, respectively; P < 0.0001) and 9 months (−15.1 ± 21.1 vs −1.9 ± 5.0 kg, respectively; P < 0.0001) after screening. Significantly greater improvement in total cholesterol, low‐density lipoprotein–cholesterol, fasting glucose, and diastolic blood pressure was seen at 3 months in patients on the LL compared with the LCHP (P < 0.05). These differences were no longer significant at 9 months, with the exception of fasting glucose. The attrition rate was elevated in the LCHP group, but did not differ significantly from the LL group. Conclusion:  Greater weight loss and improved CV risk were achieved with the LL, which mostly reflects the patient support provided for each dietary treatment.

Background:Adipose tissue functions as an endocrine organ by releasing adipokines which have important roles in the regulation of inflammation and insulin sensitivity. Although there is evidence of improvement in circulating levels of adipokines with weight loss, few studies relate such changes to specific diets. We investigated the effects of weight loss achieved by two different diets on circulating adipokine levels in obese individuals.Methods:A total of 120 obese patients (body mass index ≥ 35 kg/m2) underwent a three-month screening period on a low-fat, reduced-calorie diet. Patients failing to achieve a 5% weight loss using this approach were randomly allocated to either a low carbohydrate/high protein diet (n = 17) or to a commercial very low calorie diet (LighterLife®, n = 14) for a period of nine months.Results:At nine months, a significant weight loss was only maintained for Lighter-Life® (−32.3 ± 22.7 kg, P < 0.0001) but not on the low carbohydrate/high protein diet. Changes in adiponectin (15.8 ± 17.1 ng/mL versus −0.8 ± 6.2 ng/mL, P = 0.003) and leptin (−17.6 ± 24.3 ng/mL versus −3.0 ± 9.2 ng/mL, P = 0.049) at nine months were significantly greater for LighterLife® than for the low carbohydrate/high protein diet, which may reflect greater weight loss and decrease in fat mass. Changes in tumor necrosis factor-alpha, interleukin-6, and plasminogen activator inhibitor type 1 did not differ significantly between the dietary interventions at nine months.Conclusion:A significant weight loss of 23.8% from baseline weight was observed using a very low calorie diet and resulted in significant improvements in circulating levels of leptin, plasminogen activator inhibitor type 1, and adiponectin, which are likely to be due to weight loss and not macronutrient intake.