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.
We now know you want a robust assortment of microbes in your gut, especially in the lower gut, your colon. They feast on fiber from the food you eat and turn it into substances your body needs. Those substances send signals all over your body.
If you don’t have enough microbes or have too many of the wrong kinds, it influences those signals, which can lead to health problems.
Thanks to these efforts, we know a lot about the interactions between your gut and the rest of your body, but we don’t know exactly how many things happen — whether some teeny critters within your microbiome cause the issues or vice versa.
“That’s the problem with so much of the microbiome stuff,” said Elizabeth Hohmann, MD, a physician investigator at the Massachusetts General Research Institute. “Olympic athletes have a better gut microbiome than most people. Well, sure they do — because they’re paying attention to their diet, they’re getting enough rest. Correlation does not causation make.”
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,” Dr. 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:
“Think about a Coke. When you drink it, all the sugar goes to your bloodstream, and the microbes in your gut don’t even know you’ve had it. Instead of drinking a Coke, if you eat an apple or something with fiber, some will go to you and some to the microbes. You’re feeding them, giving them energy.”