Before diving into a new diet, think twice — consider the potential risks as well as the benefits. While the popular Keto diet is known for its weight loss results, it may not be the right choice for everyone. Recent research found that although the Keto diet can help shed pounds, it can also raise cholesterol levels and disrupt gut bacteria.

The research team from the Centre for Nutrition, Exercise, and Metabolism at the University of Bath, U.K., evaluated the impact of a keto diet and compared it with a low-sugar diet in a group of 53 healthy adults. The researchers examined how both diets affected cholesterol levels, blood sugar, weight loss, gut bacteria, and metabolism.

After tracking participants for 12 weeks, researchers observed weight loss from the low-sugar and low-carbohydrate Keto diet groups, while the control group followed a moderate-sugar diet. There was 2.9 kg fat mass loss per person for the keto diet and an average of 2.1 kg fat mass loss per person for the low-sugar diet.

However, researchers noticed that the keto diet reduced glucose tolerance levels, altered gut microbiome composition, and raised cholesterol levels, particularly small and medium-sized low-density lipoprotein (LDL) particles.

"Despite reducing fat mass, the ketogenic diet increased the levels of unfavorable fats in the blood of our participants, which, if sustained over years, could have long-term health implications such as increased risk of heart disease and stroke," lead researcher Dr. Aaron Hengist said in a news release.

In individuals who followed the keto diet, there was a reduction in beneficial bacteria, particularly Bifidobacteria, known for their probiotic benefits. These bacteria are vital for producing B vitamins, inhibiting pathogens and harmful bacteria, and lowering cholesterol.

"Dietary fiber is essential for the survival of beneficial gut bacteria like Bifidobacteria. The ketogenic diet reduced fiber intake to around 15 grams per day, half the NHS [National Health Service] recommended intake. This reduction in Bifidobacteria might contribute to significant long-term health consequences such as an increased risk of digestive disorders like irritable bowel disease, increased risk of intestinal infection and a weakened immune function," said Dr. Russell Davies, who led the microbiome research.

The keto diet also significantly altered lipid metabolism and muscle energy utilization. There was a shift in the body's fuel preference from glucose to fats.

"The ketogenic diet is effective for fat loss, but it comes with varied metabolic and microbiome effects that may not suit everyone. In contrast, sugar restriction supports government guidelines for reducing free sugar intake, promoting fat loss without apparen­­t negative health impacts," said Professor Dylan Thompson, the researcher who oversaw the work.

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