A group of health and nutrition experts from the University of Bath and collaborators from the University of Bristol, Teagasc Food Research Center, Oxford University Hospital Trusts, and Maastricht University conducted a study to explore the effects of the ketogenic diet on health. Their findings, published in *Cell Reports Medicine*, suggest that people on a ketogenic diet might experience higher levels of LDL cholesterol and apolipoprotein B, as well as a decrease in certain beneficial gut bacteria.
The study involved 53 healthy adults over 12 weeks. These participants followed one of three diets: a low-sugar diet with less than 5% of calories from sugar, a moderate-sugar diet used as a control, or a ketogenic (keto) diet with less than 8% of calories from carbohydrates.
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The results showed that those on the keto diet had increased cholesterol levels, particularly in smaller and medium-sized LDL particles. The diet also led to a rise in apolipoprotein B, a protein that can lead to plaque build-up in arteries, which is linked to heart disease. On the other hand, the low-sugar diet was found to reduce LDL cholesterol levels significantly.
Additionally, the keto diet was shown to alter the gut microbiome by decreasing Bifidobacteria, a type of beneficial bacteria often found in probiotics. These play an important role in lowering cholesterol, producing B vitamins, and preventing harmful bacteria from taking over. The low-sugar diet also did not cause significant changes in the gut microbiome.
Another significant finding was that the keto diet reduced the body’s glucose tolerance. This reduced the efficiency of the body at processing carbohydrates. On average, the keto diet participants lost 2.9 kg of fat, while the low-sugar diet ones lost 2.1 kg over the same period.
The researchers also observed that the keto diet caused major changes in how the body metabolizes fats and uses energy in muscles. This diet shifted the body’s energy source from glucose (sugar) to fats. Both diets led to fat loss without requiring participants to increase their physical activity, which is notable because earlier research had shown that skipping meals or fasting often led to reduced physical activity.
The study’s lead researcher, Dr. Aaron Hengist, expressed concerns about the cholesterol levels observed in participants on the keto diet. He pointed out that while the diet did help reduce body fat, it also increased levels of unhealthy fats in the blood. Over time, this could raise the risk of developing heart disease and stroke if these elevated fat levels persist.
Professor Javier Gonzalez, who also oversaw the research, noted that the keto diet lowered fasting glucose levels and impaired the body’s ability to manage carbohydrates after a meal. This change likely reflects an adaptive response to the low-carb intake, potentially leading to insulin resistance in muscles. This resistance might not be a problem for those strictly following a keto diet, but if the resistance persists when switching back to a diet higher in carbohydrates, it could increase the risk of type 2 diabetes in the long term.
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Dr. Russell Davies, who led the investigation into the gut microbiome, highlighted that dietary fiber is crucial for the survival of beneficial gut bacteria like Bifidobacteria. The keto diet significantly reduced fiber intake, which could have long-term health consequences, such as a higher risk of digestive disorders, infections, and weakened immune function.
Given these findings, the researchers suggest that a low-sugar diet might be a better choice for most people considering a diet change. They emphasize the need for more research to determine how different individuals might respond to each type of diet. The government recommends that free sugars make up less than 5% of total energy intake.
Professor Dylan Thompson, who was also involved in the study, commented that the keto diet is an effective diet for fat loss. But, it has varied effects on metabolism and gut health, which may not be suitable for everyone. In contrast, reducing sugar intake supports existing guidelines and promotes fat loss without apparent negative impacts on health.
Devon Andre has been involved in the health and dietary supplement industry for a number of years. Devon has written extensively for Bel Marra Health. He has a Bachelor of Forensic Science from the University of Windsor, and went on to complete a Juris Doctor from the University of Pittsburgh. Devon is keenly aware of trends and new developments in the area of health and wellness. He embraces an active lifestyle combining diet, exercise and healthy choices. By working to inform readers of the options available to them, he hopes to improve their health and quality of life.
