Beyond the Shots: Focusing on Gut Health Can Aid Weight Loss

Feb. 22, 2024 -- Injectable weight loss drugs like Wegovy, Saxenda, and Zepbound have been getting all the glory lately, but they’re not for everyone. If the inconvenience or cost of weight-loss drugs isn't for you, another approach may be boosting your gut microbiome.

So how does one do that, and how does it work?

“There are a lot of different factors naturally in weight gain and weight loss, so the gut microbiome is certainly not the only thing,” said Chris Damman, MD, a gastroenterologist at the University of Washington. He studies how food and the microbiome affect your health. “With that caveat, it probably is playing an important role.”

Trillions of Microbes

The idea that your gut is home to an enormous range of tiny organisms -- microbes -- has existed for more than 100 years, but only in the 21st century have scientists had the ability to delve into specifics. 

The American Diet Messes With Your Gut

If you’re a typical American, you eat a lot of ultra-processed foods -- manufactured with a long ingredients list that includes additives or preservatives. According to one study, those foods make up 73% of our food supply. That can have a serious impact on gut health.

“When you process a food and mill it, it turns a whole food into tiny particles,” Damman said. “That makes the food highly digestible. But if you eat a stalk of broccoli, a large amount of that broccoli in the form of fiber and other things will make its way to your lower gut, where it will feed microbes.” 

With heavily processed foods, on the other hand, most of it gets digested before it can reach your lower gut, which leaves your microbes without the energy they need to survive. 

Rosa Krajmalnik-Brown, PhD, is director of the Biodesign Center for Health Through Microbiomes at Arizona State University. Her lab has done research into how microbes use the undigested food that reaches your gut. She describes the problem with processed foods this way: 

“We found that when you feed subjects a diet designed to provide more energy to the microbes and not to the [body], our subjects lost a little weight,” Krajmalnik-Brown said. “It looks like by feeding your microbes, it seems to make people healthier and potentially even lose a little.”

Another possible mechanism involves the same hormone that powers those injectable weight loss drugs. The lower part of your gut makes hormones that tell the entire gut to slow down and also help orchestrate metabolism and appetite. Among them is GLP-1. The drugs use a synthetic version, semaglutide or tirzepatide, to trigger the same effect. 

According to Damman, you can stimulate your gut to make those helpful hormones with the food you eat -- by giving your microbes the right fuel.

Eat to Feed Your Microbes

Eating for gut health isn’t a magic bullet in terms of weight loss. But the benefits of a healthy gut go far beyond shedding a few pounds.

“I think we need to strive for health, not weight loss.” Krajmalnik-Brown said. “Keep your gut healthy and your microbes healthy, and that should eventually lead to a healthy weight. You’ll make your microbes happy, and your microbes do a lot for your health.”