The effects of low-fat, high-carbohydrate diets vs. low-carbohydrate, high-fat diets on weight, blood pressure, serum liquids and blood glucose: a systematic review and meta-analysis

Our aim was to determine the relative effectiveness of two dietary macronutrient patterns (LFHC (low-fat, high-carbohydrate) diets and LCHF (low-carbohydrate, high-fat) diets) on weight loss and cardiovascular risk factors. We searched four databases including MEDLINE, EMBASE, Cochrane Library, and Web of Science to identify the eligible studies on March 13, 2020. Randomized clinical trials (RCT) were included which compared the effect of two diets (LFHC and LCHF) on weight loss, blood pressure, serum liquids, and blood glucose in overweight or obesity adults. Standardized mean difference (SMD) and 95% confidence interval (CI) were used for the pooled results. This paper included eleven studies involving 739 participants. Compared with LFHC diets, LCHF diets had a greater effect on weight loss (SMD = -1.01 kg; 95% CI -1.99 to -0.04, p = 0.04) and HDL-cholesterol changes (SMD = 0.82 mmol/l; 95% CI 0.43 to 1.21, p < 0.0001), but a smaller effect on total cholesterol decrease (SMD = 0.63 mmol/l; 95% CI 0.18-1.08, p = 0.006) and LDL-cholesterol decrease (SMD = 0.59 mmol/l; 95% CI 0.11-1.18, p = 0.05). Between the two groups, changes in lean mass, fat mass, systolic blood pressure, diastolic blood pressure, triglycerides, and glucose were non-significant. To conclude, both diets are effective for weight control and reduction of cardiovascular risk factors. And further studies with long-term follow-up are needed to confirm our results.

Automated summary

The study found that the low-carbohydrate, high-fat diet had a more significant impact on weight loss and HDL cholesterol, but a lower effect on total cholesterol and LDL cholesterol. There were no significant differences between the two diets in terms of lean mass, fat mass, blood pressure, and blood glucose.