However, these diets also allow consumption of foods that are known to increase cardiovascular risk and are unlikely to be as effective at preventing heart disease as well-established nutritional guidelines currently recommended by health experts.
“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,” said study co-author Andrew Freeman, MD, in a press release. “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.”
Although limited data surrounding the keto diet show those who follow it initially lose weight, it tends to not be sustainable, according to 12-month data. Further, it is unclear whether the weight loss is caused by ketosis or simply by calorie restriction.
Researchers have expressed concern about the type and amount of fat consumed by those following a keto diet. Existing studies strictly controlled the type of fat and foods participants consumed. Further, many who try keto consume high amounts of unhealthy saturated fat, which is associated with an increased risk of heart disease and high lipid levels in the blood.
There is additional evidence that following a keto diet for an extended period of time may lead to stiffening of the arteries, with several studies finding that those who eat a keto diet have a greater risk of death, according to the current study.
Keto does show promise as a potential treatment for diabetes, with studies showing improved glucose levels and lower fasting glucose and insulin levels in mice, the researchers noted. However, further research is needed to confirm these benefits and assess risk before keto is clinically recommended, according to the study authors.
In terms of intermittent fasting, researchers are optimistic about the potential health benefits but are concerned about the possible pitfalls. Although some practices fast without food for an entire day, others restrict meals to certain hours of the day. This has caused researchers to worry that the hunger induced by these practices causes many people to overeat when it is time for meals or make unhealthier choices that have adverse effects on their cardiovascular health.
The current evidence surrounding the potential benefits of intermittent fasting comes from animal studies, which have shown increased longevity, weight loss, decreased blood pressure, improved glucose tolerance, and controlled lipid levels.
“The potential risks of intermittent fasting that require further study include effects of starvation and how it may impact organ function,” Freeman said in a press release. “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.”
Even with this evidence, neither the keto nor intermittent fasting dietary approach is recommended for the treatment or prevention of any condition until large, long-term studies can more definitively examine their impact, according to the study authors. Researchers recommend diets that have been extensively studied and scientifically proven to prevent or reverse cardiovascular issues, including the Mediterranean diet and the National Institutes of Health’s Dietary Approaches to Stop Hypertension.
Study examines the heart risks and benefits of today’s most popular fad diets. National Jewish Health. https://www.nationaljewish.org/about/news/press-releases/2020/study-examines-heart-risks-and-benefits-of-todays-most-popular-fad-diets#:~:text=DENVER%20%E2%80%94%20In%20a%20review%20of,may%20contribute%20to%20cardiovascular%20health. Published September 1, 2020. Accessed September 2, 2020.