The ketogenic diet, a very-low-carbohydrate and high-fat diet, has been shown to effectively promote weight loss and improve metabolic profiles, gaining increasing attention among the diabetic community.1,2 This article will focus on the current understanding of the effect of ketogenic diet on insulin resistance.
Improvements in Body Weight & Other Metabolic Profiles
Although there is a need for more rigorous trials to specifically study the effect of the ketogenic diet on insulin resistance among individuals with type 2 diabetes mellitus (T2DM), various studies have demonstrated that the ketogenic diet improves insulin resistance among obese individuals.3 A 2020 meta-analysis of 13 trials studying the effect of the ketogenic diet on individuals with T2DM found that the diet significantly improved fasting blood glucose, hemoglobin A1c, triglyceride, lipid profiles, weight, waist circumference, and body mass index. Additionally, insulin resistance measured by the homeostatic model assessment showed improvements after the ketogenic diet intervention.
As insulin resistance – a key clinical characteristic of T2DM – is closely related to obesity, it has been postulated that the ketogenic diet’s effectiveness in reducing body weight may confer beneficial effects on insulin resistance among obese individuals with T2DM.3,4
Improvements in Insulin Sensitivity, Independent of Weight Loss
In addition to improving weight and other metabolic profiles, studies have shown that the diet may reduce insulin resistance independent of weight loss.4–7 For instance, a study comparing the effect of carbohydrate-restricted diet to calorie- and fat-restricted diet in obese individuals found that in addition to other metabolic improvements (eg, weight loss and triglyceride levels), individuals assigned to the carbohydrate-restricted diet had significantly greater improvements in insulin sensitivity than those assigned to the calorie- and fat-restricted diet.5 Importantly, insulin sensitivity was shown to be improved even after adjusting for weight loss. Other studies have demonstrated that the carbohydrate-restricted diet reduces hyperinsulinemia independent of weight loss.4
The exact mechanisms of how the ketogenic diet improves insulin resistance independent of weight loss is still being elucidated, but it is hypothesized that by reducing carbohydrate intake, the ketogenic diet reduces circulating glucose and induces ketogenesis.8 This promotes the sensitivity of insulin receptors and also leads to a decreased fluctuation and secretion of insulin, eventually resulting in increased insulin sensitivity.3,8