Impact of a Ketogenic Diet on Metabolic Parameters in Patients with Obesity or Overweight and with or without Type 2 Diabetes: A Meta-Analysis of Randomized Controlled Trials

Abstract

The aim of this meta-analysis was to explore the efficacy of a ketogenic diet in metabolic control in patients with overweight or obesity and with or without type 2 diabetes. Embase, PubMed, and Cochrane Library were searched for randomized controlled trials that enrolled patients with overweight or obesity on a ketogenic diet for metabolic control. Fourteen studies were included in meta-analysis. The effects of ketogenic diets on glycemic control were greater for diabetic patients relative to those of low-fat diets, indicated by lower glycated hemoglobin (SMD, -0.62; p < 0.001) and homeostatic model assessment index (SMD, -0.29; p = 0.02), while comparable effects were observed for nondiabetic patients. Ketogenic diets led to substantial weight reduction (SMD, -0.46; p = 0.04) irrespective of patients' diabetes status at baseline and improved lipid profiles in terms of lower triglyceride (SMD, -0.45; p = 0.01) and greater high-density lipoprotein (SMD, 0.31; p = 0.005) for diabetic patients. Other risk markers showed no substantial between-group difference post intervention. Our study findings confirmed that ketogenic diets were more effective in improving metabolic parameters associated with glycemic, weight, and lipid controls in patients with overweight or obesity, especially those with preexisting diabetes, as compared to low-fat diets. This effect may contribute to improvements in metabolic dysfunction-related morbidity and mortality in these patient populations.

Keywords: glycemic control; ketogenic diet; obesity; type 2 diabetes.

Figure 1

Study selection diagram. Abbreviation: RCT, randomized controlled trial.

Figure 2

Risk of bias summary.

Figure 3

Forest plots for association between glycemic control and ketogenic diet in patients with overweight or obesity and with or without T2DM: (a) Changes in fasting glucose; (b) changes in HbA1c; (c) changes in fasting insulin; (d) changes in C-peptide; (e) changes in HOMA. Abbreviations: CI, confidence interval; DM, diabetes mellitus; Non-DM, non-diabetes mellitus; HbA1c, glycated hemoglobin; HOMA, homeostatic model assessment; T2DM, type 2 diabetes mellitus.

Figure 4

Forest plots for association between weight control and ketogenic diet in patients with overweight or obesity and with or without T2DM: (a) Changes in body weight; (b) changes in BMI; (c) changes in waist circumference. Abbreviations: CI, confidence interval; BMI, body mass index; T2DM, type 2 diabetes mellitus.

Figure 5

Forest plots for association between lipid control and ketogenic diet in patients with overweight or obesity and with or without T2DM: (a) Changes in total cholesterol; (b) changes in triglyceride; (c) changes in LDL; (d) changes in HDL. Abbreviations: CI, confidence interval; DM, diabetes mellitus; Non-DM, non-diabetes mellitus; LDL, low-density lipoprotein; HDL, high-density lipoprotein; T2DM, type 2 diabetes mellitus.

Figure 6

Forest plots for association between other risk markers and ketogenic diet in patients with overweight or obesity and with or without T2DM: (a) Changes in systolic blood pressure; (b) changes in diastolic blood pressure; (c) changes in C-reactive protein; (d) changes in serum creatinine. Abbreviations: CI, confidence interval; T2DM, type 2 diabetes mellitus.