A recent study involving 53 healthy adults reveals that the ketogenic diet may aid in weight loss but does not improve heart health markers and could negatively impact gut microbiome diversity. Conducted over 12 weeks, the research compared three diet groups: ketogenic, low-sugar, and moderate-sugar, and found significant differences in outcomes related to fat mass, cholesterol levels, and gut health.
The ketogenic diet group consumed approximately 40% less dietary fiber than the control diet. Despite reducing fat mass by 2.9 kilograms, the diet did not improve heart health markers. In contrast, the low-free sugar diet reduced fat mass by 2.1 kilograms and achieved a 0.5 millimoles per liter (mmol/L) reduction in LDL cholesterol without negatively impacting gut microbiota.
Study author Javier Gonzalez highlighted the importance of considering the broader health impacts of diet choices. “The free sugar restriction achieves this with almost entirely favorable health effects, whereas the ketogenic diet achieves the weight loss with some trade-offs we may need to be cautious about,” Gonzalez stated.
How does the keto diet affect gut health?
The study found that the ketogenic diet significantly affected the gut microbiome, leading to a reduction in healthy gut bacteria. This reduction may negatively impact colonic health and contribute to risks of obesity, type 2 diabetes, and depression. Sarah Herrington noted, “Long-term effects of a ketogenic diet may include more significant changes to the gut microbiome, potentially leading to less overall diversity.”
In terms of glucose tolerance, the ketogenic diet may worsen the body’s sensitivity to sugars and carbohydrates when reintroduced into the diet. Herrington added, “It may also worsen glucose tolerance — the body will be more sensitive to sugars and carbohydrates when they are reintroduced into the diet.”
The World Health Organization recommends that free sugars make up less than 10% of total energy intake due to their links to chronic diseases. The low-free sugar diet in the study focused on nutrient-rich whole foods while limiting sugary snacks, beverages, and processed foods with added sugars. Lucia Aronica, PhD, emphasized this approach: “A healthy, free-sugar-restricted diet would focus on nutrient-rich whole foods such as fruits, vegetables, lean proteins, and whole grains.”
Existing dietary guidelines already advise reducing free sugars and added sugars to improve health. Alyssa Simpson, RDN, commented on the sustainability of such diets, stating, “A low-sugar diet might be a more sustainable and appropriate option for long-term weight loss and overall health.”
Gonzalez plans to continue this research and is actively seeking more funding for future studies. “We have just received a large Medical Research Council grant for some of this work and are actively seeking more funding for the rest,” he shared.
The findings suggest that while the ketogenic diet may support weight loss, it does not necessarily translate to better heart health or improved gut microbiome diversity. Researchers recommend a balanced approach that includes reducing free sugars and focusing on whole foods for overall health benefits.
Parts of this article has been sourced by Healthline and fact-checked by Jill Seladi-Schulman, Ph.D.
Featured Photo by Travis Yewell on Unsplash
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