Ketogenic, intermittent fasting diets may be heart-healthy
There is modest evidence that the ketogenic and intermittent fasting diets may have favorable CV effects, according to a review published in the American Journal of Medicine.
While noting that “both allow foods that are known to increase the risk of cardiovascular disease,” Melroy S. D’Souza, MD, resident at Emory University School of Medicine, and colleagues wrote that “either dietary plan may be beneficial, if the general criteria of established ‘heart-healthy’ diets are also followed.”
The researchers wrote that clinicians may consider recommending a ketogenic or intermittent fasting diet to mitigate CV risk factors, but only “after a careful evaluation of a patient’s metabolic profile and comorbidities.”
“Both dietary approaches require better controlled and long-term studies to completely establish their role in mitigating the effects of the metabolic syndrome along with additional clarity on their efficacy and safety,” they wrote.
However, Andrew Freeman, MD, FACC, FACP, director of cardiovascular prevention and wellness at National Jewish Health in Denver and an author of the review, told Healio that more proven heart-healthy diets should be preferred.
“With diets like keto and intermittent fasting, social and popular media has been flooded with claims, promises and warnings that are at best unverified and at worst harmful to your health,” he said in an interview. “Diets recommended by health experts, such as plant- based and Mediterranean diets, have been extensively studied for safety and efficacy, and demonstrated conclusively to improve cardiovascular health.”
The ketogenic diet pattern, which limits daily carbohydrate intake to 50 g or less or 10% or less of daily calorie intake, has been shown to reduce weight in patients with obesity, but evidence of its effects on lipid levels is mixed and the quality of studies in this area has been poor, D’Souza and colleagues wrote.
There is evidence that low-carbohydrate diets reduce BP, but none of those studies evaluated the ketogenic diet specifically. However, the ketogenic diet has been shown to improve glucose metabolism in patients with type 2 diabetes or at risk for it, according to the authors.
There are no studies in humans on whether the ketogenic diet reduces risk for CVD, but mouse studies suggest it might, D’Souza and colleagues wrote. The diet has been shown to increase inflammatory markers, but it is unclear whether this is of any clinical significance, they wrote.
“The restrictive nature of the [ketogenic] diet might lead to an unregulated intake of foods that are known to cause harm,” the authors wrote. “Therefore, the recommendation to start the ketogenic diet for patients must be made prudently, as this dietary approach will likely not be appropriate for most people. In patients who are meticulous, disciplined and motivated, the ketogenic diet might be a reasonable approach to employ for cardiovascular disease prevention.”
Intermittent fasting diet
The intermittent fasting diet has been shown to reduce weight in patients with obesity, although evidence is mixed on effects on lipids, according to the researchers.
Alternate-day fasting and time-restricted eating have been associated with reduction in BP, and there is evidence that intermittent fasting can help prevent the onset of diabetes, but its effectiveness at management of diabetes is unknown, D’Souza and colleagues wrote.
Routine fasting has been associated with reduced risk for CAD, so intermittent fasting may help prevent CVD, although more research in this area is necessary, according to the authors.
Among patients with diabetes, intermittent fasting may raise risk for hypoglycemia or diabetic ketoacidosis.
“Further work to elucidate the circadian rhythm and its impact on metabolism may guide optimal fasting-feeding cycles,” D’Souza and colleagues wrote. “The concerns raised with the ketogenic diet also hold true for intermittent fasting, such as consuming saturated fats, red meat and refined sugar, which would negate the benefits of fasting.”
Freeman told Healio that “The potential risks of intermittent fasting that require further study include effects of starvation and how it may impact organ function. It is particularly important for diabetics to speak with their doctor before trying intermittent fasting to discuss how to control their disease and the risk of hypoglycemia that may come with skipping regular meals.”