Ketogenic diets, which forgo carbohydrates to replace them with fats, have become extremely popular in recent years, rising to the top as the most-searched-for diet of 2020. Whilst these diets are effective in treating epilepsy and have applications in various other diseases, the evidence for use as a tool for weight loss in healthy individuals remains disputed. 

In a recent study performed on rats, researchers have suggested that keto diets are having a dramatic impact on people’s hearts. The results showed the high-fat-diet-induced changes within the rats’ hearts, reducing the production of mitochondria and creating scar tissue. Their work was published in the journal Signal Transduction and Targeted Therapy. 

The basis of ketogenic diets revolves around bringing the body into a state of ketosis through consuming mostly fats. Ketosis is a normal metabolic response that kicks in when the body doesn’t have enough glucose to ensure enough energy is provided. The liver begins turning fat molecules into ketones, which are released into the bloodstream and used as an alternative energy source.  

As this process consumes fat molecules and lowers blood glucose and insulin levels, the diet has become popular among people looking for weight loss. The jury is still out on whether ketogenic diets are safe and effective for long-term weight goals, with many swearing by the success they have had and others disputing it as an alternative to traditional weight-loss methods.

In the latest piece of research, a collaboration between Fudan University, Shanghai, and Sichuan University, Chengdu, the researchers delved deeper into the cellular impacts of ketosis on the heart. The most abundant ketone body formed during ketosis is β-OHB (70 percent of all ketones), which has been thought to have multiple secondary benefits for the immune system. However, research has suggested that elevated β-OHB is linked with poorer cardiac health, alongside various other concerning correlations between ketosis and mortality. 

The study involved three groups of six rats that were fed either a ketogenic diet, normal diet, or calorie-restricted diet over a period of four months. After the four months, the rats’ hearts were analyzed to look for cellular changes between each diet. In the ketogenic group, the rats demonstrated an increase in the ketone β-OHB levels and a resulting activation of the gene Sirt7, inhibiting the biogenesis of mitochondria. Furthermore, when this pathway was translated to human cultured cells, it led to apoptosis (cell death) of cardiac cells and fibrosis (scarring). 

These results do not provide clear evidence that ketogenic diets damage the human heart, nor that all ketogenic diets should be stopped. Cellular and animal models were used and there is no data on the long-term effects of ketosis on human organs, which would require more extensive testing and clinical trials. However, it does highlight an avenue of inquiry that should be followed to ensure ketogenic diets are safe for use as a weight-loss tool. The authors call for further trials over a longer period, but in the meantime suggest ketogenic diets should be avoided for weight loss unless required by a health condition.