To keto or not to keto?

On the one hand, keto has been shown to help with body fat reduction — particularly the visceral fat in your belly that can raise your risk of heart disease. It also has been connected to lower blood pressure and reduced inflammation in the body and brain.

On the other, low carbohydrate diets like keto have been linked to atrial fibrillation and diabetic ketoacidosis. And while it can help with weight loss in the short term, its high fat and caloric content make it difficult to maintain that weight loss over the long term.

Now there’s even more evidence keto isn’t all it’s chalked up to be…

That’s because it can increase the risks of developing high cholesterol and type 2 diabetes — both risk factors for stroke — by disrupting your gut microbiome.

Keto’s triple whammy

University of Bath researchers studied 53 healthy adults for up to 12 weeks. Participants followed one of three diets: a moderate sugar diet (the control group); a low-sugar diet where less than 5 percent of calories came from sugar; and a ketogenic low-carbohydrate diet where less than 8 percent of calories came from carbs.

After 12 weeks, the researchers found the keto diet raised cholesterol levels, particularly LDL (bad cholesterol), and increased apolipoprotein B (apoB), which causes plaque buildup in arteries. By contrast, the low-sugar diet significantly reduced LDL particle cholesterol.

Lead researcher Dr. Aaron Hengist noted that if this increase in cholesterol is sustained over years, it “could have long-term health implications such as increased risk of heart disease and stroke.”

The keto diet also altered the composition of the gut microbiome, including a decrease in Bifidobacteria. Often found in probiotics, Bifidobacteria produce B vitamins, inhibit pathogens and harmful bacteria and lower cholesterol. Sugar restriction, by contrast, did not significantly impact gut microbiome composition.

“Dietary fiber is essential for the survival of beneficial gut bacteria like Bifidobacteria,” says Dr. Russell Davies, who led the microbiome research. He noted the keto diet reduced fiber intake to around 15 grams which is half the recommended daily 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,” Davies adds.

Finally, the keto diet reduced glucose tolerance. This means the participants’ bodies became less efficient at handling carbs.

Javier Gonzalez, who oversaw the research, notes while the keto diet lowered fasting glucose levels, it also reduced the body’s ability to handle carbs from a meal.

“By measuring proteins in muscle samples taken from participants’ legs, we think this is probably an adaptive response to eating less carbohydrates day to day and reflects insulin resistance to storing carbs in muscle,” Gonzales says. “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.”

Still good for weight loss

Now for the good news: both the low-sugar and keto diets resulted in fat loss. At 12 weeks, the keto diet resulted in an average of 2.9 kg in fat loss per person, while individuals on the sugar-restricted diet had an average fat loss of 2.1 kg. Both these diets achieved fat loss without changing physical activity levels.

Researchers also observed the keto diet shifted the body’s fuel preference from glucose to fat, which resulted in significant changes in lipid metabolism and muscle energy use.

Based on these results, the researchers conclude that if you’re looking to lose weight, a low-sugar diet will be better for most people than a keto diet, since it promotes fat loss without any apparent negative health impacts.

Whichever of these diets you choose, it couldn’t hurt to supplement it with probiotics to protect your gut health. While probiotic supplements in pill form are good for convenience (as long as the bacteria are live), it’s even better to get your probiotics from fermented foods like yogurt, kefir, sauerkraut, kimchi and kombucha. These foods come with additional nutrients like vitamins, minerals and fiber, which can further support good health.

Sources:

Ketogenic Diet reduces friendly gut bacteria and raises cholesterol levels – University of Bath study — EurekAlert!

Ketogenic diet but not free-sugar restriction alters glucose tolerance, lipid metabolism, peripheral tissue phenotype, and gut microbiome: RCT — Cell Reports Medicine

The effects of probiotics on cholesterol levels — Easy Health Options

Low-carb diet tied to common heart rhythm disorder — Science Daily