• Kimmie Gilbert couldn't seem to lose weight despite trying diets, exercise, and medication. 
  • Research suggests that gut microbiome composition might play a role in a person's weight.
  • Gilbert got her stool analyzed in a lab and found that she was lacking some key microbes.

Kimmie Gilbert has one pressing question: "What in the world are y'all eating that I'm not eating that causes y'all to lose weight and not me?"

The answer to her problem, which many people will relate to, might lie in the composition of her gut microbiome, the trillions of microbes that live in the colon lining, experts told the Netflix documentary "Hack Your Health: The Secrets of Your Gut."

To find out whether her gut microbiomes were playing a role in her struggle to lose weight, she sent off a stool sample to be analyzed by a commercial lab, as growing evidence suggests that gut health impacts overall health.

Using healthcare tech like this is becoming increasingly mainstream. From tracking blood sugar levels with a wearable continuous glucose monitor to measuring VO2 max, the personalized medicine and health optimization industry is growing. In 2019, health tech had a global market value of approximately $350 billion, according to McKinsey.

Previously, Gilbert had tried it all, from expensive gym memberships to countless diets and even weight loss medication, but none of it helped her control her weight long-term.

"I would lose a lot of weight at first, but then it just comes right back," the single mom of three based in New Orleans told the documentary.

Even though she didn't have any health problems, Gilbert's BMI technically put her in the morbidly obese category. As diabetes runs in her family, and she wants to be around for as long as possible for her kids, she said she wanted to lose weight to prevent health conditions associated with excess weight.

Related stories

"You can be positive in the body that you're in but also be conscious of your health because you ultimately need that," she said.

Gilbert had low levels of microbes associated with weight loss and feeling full

Eran Segal, a computational biologist at the Weizmann Institute of Science, and Annie Gupta, an assistant professor at UCLA and co-director of the Goodman-Luskin Microbiome Center, talked Gilbert through the results in the documentary.

"Each teaspoon of stool contains terabytes and terabytes of information encoded in the DNA of the microbes," Rob Knight, a computer scientist at UC San Diego, said in the documentary.

An individual sample can't tell scientists much about a person's health, but by comparing it to thousands of other people's samples and seeing where it fits in, they can make strong predictions, Jack Gilbert, a microbial ecologist at UC San Diego, said.

"Does your microbiome look like people who are obese? Are you obese? If that's true, then I can find a signature that can help me unpin that," he said.

They found that Gilber's microbial community was less diverse than those of people who were considered a healthy weight. One large 2008 study found that people with obesity tended to have similar microbiomes with low diversity.

A microbe called Prevotella, which is associated with weight loss, wasn't found at all in her gut. "People who have that pattern of no Prevotella have a hard time losing weight," Gupta told the documentary. In a 2018 study based on 52 overweight people, those who had higher levels of Prevotella lost significantly more weight than those with low levels.

The researchers also found that she had low quantities of three other types of bacteria associated with a gut hormone that makes you feel full.

No bacteria acts alone, Segal said: "They act within an ecosystem, which is why we analyze the microbiome as a whole."

The experts recommended Gilbert make an enjoyable but sustainable lifestyle change that would help her repopulate her gut with more "good" bacteria. Eating 20 to 30 fruits and vegetables a week is usually considered beneficial, Gupta said.

"The good news is you got here, but you can also get out," she said.