Researchers may have figured out why vegan diets lead to weight and fat loss even if dieters don’t cut calories

There's even more evidence to suggest switching to plant-based eating may be better for your health.

A new study found that overweight and obese adults who switched to a vegan diet had healthier microbiomes, or good gut bacteria, and better insulin sensitivity, which protects against diabetes, than non-vegans. As a result, they also lost weight and body fat without restricting calories. 

For the study, researchers from the Physicians Committee for Responsible Medicine looked at 148 overweight and obese adults over a period of 16 weeks, half of whom were instructed to follow a low-fat vegan diet.

Participants on the vegan diet lost a significant amount of weight compared with those who stuck with their ordinary, non-vegan eating habits, according to the research, which was presented at the 2019 annual meeting for the European Association for the Study of Diabetes.  

And, of the total weight loss by the vegan group, nearly two-thirds was body fat, researchers found. 

Read more: There's a keto diet for vegetarians that shuns meat and carbs. These 7 meals illustrate what foods are left.

These findings support previous research that plant-based diets can offer significant health benefits and boost weight-loss efforts. Importantly, though, the new research also provides evidence on how this works: The study found high levels of healthy gut bacteria were likely responsible for the health benefits of vegan diets.

Vegan diets lead to weight loss by boosting gut bacteria, researchers found

"Eating a plant-based diet with ample fiber changes the gut microbiome composition for the better by feeding the right kind of bacteria," Dr. Hana Kahleova, lead author and director of clinical research at the Physicians Committee for Responsible Medicine, told MedScape Medical News. 

She explained that the study's goal was to explain previous research showing that vegans lost up to twice as much weight as non-vegans while consuming the same number of calories. 

Kahleova's team found that participants on the vegan diet had more of a type of gut bacteria called bacteroidetes, which digest fiber and produce compounds called short-chain fatty acids. These fatty acids are associated with metabolic health.

A particular species called Faecalibacterium prausnitzii, which thrives on the fiber found in plant-based products, is linked to weight loss, especially a reduction in body fat. It can also improve insulin sensitivity, which is important for metabolic health and preventing diabetes.

More research is needed to understand how to maximize the health benefits of veganism 

This study specifically looked at how a low-fat vegan diet can improve metabolic health, but other studies have shown there are benefits to high-fat plant-based eating habits such as the Mediterrean diet. 

Kahleova told Medscape her future research will look at participants' gut bacteria to compare a low-fat vegan diet with other types of nutrition plans, including the Mediterranean diet, a high-fat vegan diet, and a meal plan recommended to manage diabetes. 

However, veganism can present its own challenges. It can be difficult for some people to sustain because it restricts the use of all animal products; nutritionists say sustainable diets are healthier in the long term. Veganism may also make it difficult to get enough of certain nutrients, such as B vitamins and iron, according to dietitians. 

Read more: 

There's a keto diet for vegetarians that shuns meat and carbs. These 7 meals illustrate what foods are left.

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