Keto Diet: Gut Health & Cholesterol Risks
- A ketogenic, or keto, diet, while effective for fat loss, may come with health risks, including increased cholesterol levels and reduced beneficial gut bacteria, according to new research.
- The research indicated that the keto diet, which restricts carbohydrate intake to less than 8% of calories, raised cholesterol levels, particularly small and medium LDL particles.
- Furthermore, the keto diet altered the gut microbiome composition, decreasing Bifidobacteria, a beneficial bacteria often found in probiotics.
A new study reveals the keto diet’s potential downsides: increased cholesterol and gut health risks. Researchers found the keto diet, effective for fat loss, elevates LDL particles and reduces beneficial gut bacteria like Bifidobacteria, vital for overall health. The study, published in Cell Reports Medicine, pitted keto against low-sugar diets, showing the keto diet impaired glucose tolerance. While both promoted fat loss,the keto approach altered the gut microbiome,impacting vitamin production and cholesterol balance. The low-sugar approach seemed more promising.For detailed health breakdowns, explore this crucial data, brought to you by News Directory 3, and discover how diet impacts long-term wellbeing. Discover what’s next in dietary science.
Keto Diet Linked to Increased Cholesterol and Gut Health Risks
Updated June 11, 2025
A ketogenic, or keto, diet, while effective for fat loss, may come with health risks, including increased cholesterol levels and reduced beneficial gut bacteria, according to new research. The study, published in Cell Reports medicine, examined the effects of moderate sugar, low-sugar, and keto diets on 53 healthy adults over 12 weeks.
The research indicated that the keto diet, which restricts carbohydrate intake to less than 8% of calories, raised cholesterol levels, particularly small and medium LDL particles. It also increased apolipoprotein B (apoB),a substance that can lead to plaque buildup in arteries. In contrast, a low-sugar diet, with less than 5% of calories from sugar, considerably reduced cholesterol in LDL particles.
Furthermore, the keto diet altered the gut microbiome composition, decreasing Bifidobacteria, a beneficial bacteria often found in probiotics. This bacteria aids in producing B vitamins, inhibiting harmful bacteria, and lowering cholesterol. Sugar restriction did not significantly impact gut microbiome composition. The study also found that the keto diet reduced glucose tolerance, making the body less efficient at processing carbohydrates.
Both the keto diet and the sugar restricted diet resulted in fat loss, with the keto diet averaging 2.9 kg of fat mass loss per person and the sugar restricted diet averaging 2.1 kg. Researchers also observed that the keto diet caused changes in lipid metabolism and muscle energy use, shifting the body’s fuel preference from glucose to fats. Fat loss was achieved without changes in physical activity levels.
“Despite reducing fat mass, the ketogenic diet increased the levels of unfavourable 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,” said Dr. Aaron Hengist, lead researcher.
“Dietary fibre is essential for the survival of beneficial gut bacteria like Bifidobacteria. The ketogenic diet reduced fibre intake to around 15 grams per day, half the NHS recommended intake… this reduction in Bifidobacteria might contribute to critically important 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,” explained Dr. Russell Davies, who led the microbiome research.
“The ketogenic diet reduced fasting glucose levels but also reduced the body’s ability to handle carbs from a meal… This insulin resistance is not necessarily a bad thing if people are following a ketogenic diet, but if these changes persist when people switch back to a higher carbohydrate diet it could increase the risk of developing type 2 diabetes in the long-term,” commented Professor javier Gonzalez, who oversaw the research.
What’s next
The researchers suggest that a low-sugar diet may be a better option for most people, aligning with government guidelines for reducing free sugar intake. Further research is needed to understand how individuals may benefit from each type of diet.