The keto diet has been linked to weight loss and other health benefits

Concerned About Your Gut or Heart Health? You May Want to Avoid the Keto Diet However, it may not be the best eating pattern for your gut or heart health

The keto diet has been linked to weight loss and other health benefits

• Though it can be helpful for weight loss, the keto diet might also reduce beneficial gut bacteria and increase cholesterol levels, a new study found.
• In contrast, a low-sugar diet did not impact microbiome diversity and lowered LDL cholesterol.
• The keto diet tends to be lower in fiber and prioritize fats, which could explain why it’s not as beneficial for heart and gut health, experts said.

A keto diet might help you lose weight, but it may not be the best choice for cardiac or gut health—instead, a low-sugar diet might be a better option. 

A new study—published on August 20 in Cell Reports Medicine—found that people who followed a keto diet had decreased gut microbiome diversity and increased total cholesterol. However, those who followed a diet that was simply low in sugar saw fewer effects on their gut microbiome and also had lower amounts of LDL (or “bad”) cholesterol.

The keto diet has been linked to weight loss and improved blood sugar control, which is achieved by eating lots of fats and very few carbohydrates. However, eating this way could have unintended consequences on a person’s heart and gut health.

Here’s what experts had to say about the new research and why choosing a low-sugar diet could be a healthier alternative to keto.

How a Keto Diet Affects the Body

For this study, researchers originally started wanted to look at why low-carb diets result in weight loss and how many calories people burn while following these diets in their normal lives, explained study author Javier Gonzalez, PhD, professor at the University of Bath Centre for Nutrition, Exercise, and Metabolism.

But as Gonzalez and his colleagues explored these questions, they uncovered interesting results on the ways in which low-carb diets affect other health measures.

The team recruited 53 healthy adults between ages 18 and 65 and split them into three groups—one cohort followed a normal moderate-sugar diet, while the other two were assigned to either a low-sugar or ketogenic diet.

There are no definitive parameters around these diets, but the American Heart Association recommends that a low-sugar diet should contain no more than 6% of calories from added sugars. A keto diet, on the other hand, dictates a stricter macronutrient breakdown.

“The ketogenic diet is characterized by a very low intake of carbohydrates and a moderate intake of protein, which means individuals rely heavily on fats to meet their calorie needs,” Veronica Rouse, MAN, RD, cookbook author and owner of The Heart Dietitian, told Health. This macronutrient breakdown varies but usually involves eating 55–60% of daily calories from fat, 30–35% from protein, and 5–10% from carbohydrates.

For the purpose of this Cell Reports Medicine study, Gonzalez’s team defined a low-sugar diet as one that contained less than 5% of calories from added sugars, while a keto diet was defined as a carbohydrate intake below 8% of total calories.

Over 12 weeks, the researchers analyzed the study participants’ urine, fecal, and blood samples to measure their metabolic, cardiovascular, and gastrointestinal health.

They found that the keto diet elevated subjects’ levels of cholesterol and apolipoprotein B, a protein often used to detect the risk of atherosclerotic cardiovascular disease. People who followed this diet also had a decreased abundance of Bifidobacteria and other beneficial bacterial strains in their guts.

A low-sugar diet, however, had different effects—sugar restriction reduced LDL cholesterol and total cholesterol and did not alter the microbial diversity of the gut.

Both the keto and low-sugar diets yielded weight loss, with the most dramatic losses occurring in the first four weeks of the study and plateauing thereafter.

Why Might Lowering Carbs Impact Gut and Heart Health?

Some health experts say they’re not surprised that this new research found keto diets could adversely impact the gut and heart (and low-sugar diets could do the opposite). 

The keto diet has long been dogged by a reputation for being less than cardiac-friendly, largely due to its focus on consuming a high percentage of calories from fats—especially the saturated kind.

“Diets that are excessively high in saturated fats can increase LDL cholesterol levels, which contributes to arterial plaque formation and elevates the risk of heart disease,” said Rouse. “This is exactly what this study showed.”

Reducing sugar, however, is associated with positive changes for heart health. A 2022 study, for example, concluded that restricting sugar to lower than 10% of a person’s daily calorie intake is “vital” to reducing cardiovascular disease risk. 

Additionally, the keto diet tends to be low in fiber, which can be a red flag for both heart health and gut health.

“The lack of fiber in a ketogenic diet can negatively affect LDL cholesterol levels, as soluble fiber is helpful for lowering cholesterol,” said Rouse.

Similarly, this low fiber intake is also likely responsible for the negative changes in gut microbial diversity that Gonzalez and his team noticed among participants on the keto diet.

“Diversity in plant foods creates diversity in the gut microbiome,” Kim Kulp, RDN, gut health expert and owner of the Gut Health Connection, told Health. “Since the keto diet limits so many plant foods including fruit, whole grains, and legumes, there is much less available to feed the gut microbes, which decreases their number and variety.”

But low-sugar diets don’t usually restrict these nutritious foods, making them less likely to have the same negative effects on the gut.

“A low-sugar diet tends to emphasize the whole, unprocessed foods that we like to encourage for a healthy microbiome: a variety of fruits, vegetables, whole grains, and fibers,” Ritu Nahar, MD, a gastroenterologist with Allied Digestive Health, told Health.

“Having a diverse microbiome is so important for balancing the gut environment,” she said. “It’s even been linked in other research to improved digestive health, stronger immune systems, and lower inflammation levels.”

Should You Opt for a Low-Sugar Diet Over Keto?

Research on keto diets in general is mixed—other experts have even hypothesized that going on a keto diet could actually positively impact a person’s gut microbiome and improve certain markers of heart disease.

Because of this—and because this Cell Reports Medicine study was limited in scope—further research is needed to provide more answers about how a keto diet affects cardiovascular and gut health in particular.

For now, though, if these areas of health are top concerns for you, it’s best to weigh the pros and cons of a keto diet with your doctor and discuss whether a low-sugar diet might be a better option.

“While the keto diet can offer benefits for specific health concerns, the long-term impact of a lower fiber intake and higher fat consumption on your gut health might be unfavorable,” said Nahar.

Rouse said the same is true for your heart.

“A low-sugar diet would be more favorable for heart health compared to a ketogenic diet because it allows for the inclusion of a variety of fruits, vegetables, and whole grains, which provide essential soluble fiber that can lower LDL cholesterol levels,” she said.

This story originally appeared on: Health News - Author:Sarah Garone