Abstract
The effect of a ketogenic diet (KD) on biochemical parameters and nutritional status has been the subject of debate over the years, as several randomized clinical trials (RCTs) obtained different results. Method: A systematic review and random-effects meta-analysis of RCTs comparing KD with a balanced diet was performed by means of a search of PubMed, Cochrane Library, Scopus, and Web of Science. Trials where the method for measuring the response variables was unclear, those that considered pathologies other than chronic non-communicable diseases and those with participants receiving pharmacological treatment for obesity were excluded from the comparison. Results: Of the studies included in the meta-analysis, no statistically significant standardized mean differences were observed for body mass index (BMI) (d = −0.457, p = 0.359), total cholesterol, COL-T (d = 0.230, p = 0.591), high-density lipoprotein, HDL (d = −0.028, p = 0.934), low-density lipoprotein, LDL (d = 0.528, p = 0.173), or triglycerides, TG (d = −0.283, p = 0.222), with high values of heterogeneity. The percentage of women included in the studies is a significant moderating variable in terms of BMI ratio (z = −6.68, p < 0.001) and TG (z = −2.27, p = 0.023). Conclusion: A KD shows no more benefits on nutritional parameters than a balanced diet, and adverse effects of being on the diet are sometimes reported.
Highlights
The impact of obesity on people’s well-being and the resulting increase in the risk of chronic non-communicable diseases [1,2,3,4] are well-known facts about the condition
Based on the controlled data of three clinical trials with the same duration of intervention (Figure 3), ketogenic diet (KD) was not found to provoke a significant change in body mass index (BMI) (d = −0.46, 95% CI −1.43 to 0.52 kg/mt2, p = 0.359), with a high heterogeneity value (Q = 35.25, p < 0.001, I2 = 94.33%)
In clinical trials whose samples include a higher percentage of women, the KD intervention decreases BMI, z = −6.68, p < 0.001 (Figure 4)
Summary
The impact of obesity on people’s well-being and the resulting increase in the risk of chronic non-communicable diseases [1,2,3,4] are well-known facts about the condition. The public often looks to take advantage of diets without understanding their primary objective or potential risks. One popular diet is the ketogenic diet (KD), developed in 1924 by Russell Wilder for the treatment of motor neuron diseases [6,7]; it has been successfully used for some types of epilepsy [8]. A very low carbohydrate ketogenic diet (VLCKD) intervention consists of an increased proportion of fat (44%) and protein (43%) and minimal glycemic intake (
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