Can a saliva test predict the best way to manage obesity?
May 23, 2023 – Sounds like a simple solution to a complicated problem: Check out this kind obesity you have based on a unique genetic saliva test. Then you and your doctor can get a better idea of whether anti-obesity drugs or other treatments are more likely to work for you.
The goal of creating obesity types and tests is to increase your chances of losing weight and improving your health and well-being, compared to a one-strategy approach. That’s what Mayo Clinic researchers had in mind when they created four obesity phenotypes.
Obesity experts unaffiliated with the research have concerns and say independent studies are needed to verify the strategy’s potential.
This research could help predict who will respond best to popular anti-obesity drugs, said Andres Acosta, MD, PhD, co-founder of Phenomix Sciences, the company behind the tests. These drugs include the class of drugs called glucagon-like peptide receptor (GLP-1) agonists such as liraglutide (Saxenda, Victoza) and semaglutide (Ozempic, Wegovy).
“We know not everyone on a GLP-1 will respond. In fact, about a third of patients do not do well on GLP-1s,” said Acosta, assistant professor of medicine and researcher in the Division of Gastroenterology and Hepatology at the Mayo Clinic in Rochester, MN.
The “My Phenome Hungry Gut” test is the most advanced in development to predict the GLP-1 response. People in this Hungry Gut group tend to empty their stomachs faster after a meal and are more likely to feel hungry again soon after, as explained on the company’s website.
A pilot study to test how well it works began in April in three primary care practices. There are plans to expand real-world testing for this type of obesity and others later this year.
The other categories of obesity are:
- “Hungry Brain”, where the brain does not recognize signals that the stomach is full
- “Emotional hunger”, where food cravings are driven by emotions, anxiety, and negative feelings
- “Slow Burn”, where people have a slow metabolism and low energy levels
People in these categories may be more likely to benefit from other obesity management strategies, such as changes to their diet or implementing a intragastric balloon.
A few things to consider
While applauding their efforts to be more specific in treating obese people, not all experts are convinced that this saliva test will be the answer. The company’s research may look promising, but checking the results is warranted.
“Can we get better results with things like this? Well, that’s the hope,” said Jaime Almandoz, MD, medical director of Weight Wellness at the University of Texas Southwestern Medical Center at Dallas.
“We still don’t have randomized trials where we look at obesity phenotyping,” said Almandoz, who is also a spokesperson for The Obesity Society, a professional group of clinicians, researchers, educators and others focused on obesity science, treatment and prevention.
There are always concerns when a diagnostic test is developed for commercial use, said Daniel Bessesen, MD, professor of medicine-endocrinology, metabolism and diabetes at the University of Colorado Denver School of Medicine. “What they talk about doing is super important. But it’s a business. It’s a company that I think sells a product.
In an online search, Bessesen found no external studies showing how well the saliva test worked. But referring to the work of Acosta and Michael Camilleri, MD, Phenomix’s other co-founder, he said, “I found articles they wrote that I hadn’t read before that are good.”
“These guys are smart guys. And they did a lot of work on [the movement of food through the gut] and how it correlates with obesity and response to certain therapies,” said Bessesen, who is also a spokesperson for The Obesity Society. “So their scientific work aligns with that area.”
Validation of any research is important because the obesity industry is known for many rapid weight loss strategies, some with little or no science behind them, he said.
It’s also critical, he said, because “anytime you do anything commercial in the area of obesity, you have to recognize that obese people are a vulnerable population. These people constantly face stigma and prejudice.
Remove the stigma
If knowing your type of obesity ends up making a difference, it could change the conversation people have with their doctor, Acosta said. It could also help remove some of the stigma surrounding obesity.
“We’re going to change the conversation because now we can say, ‘Hey, you’re obese because you have the ‘Hungry Gut’ phenotype. And because of that, you’re going to react to this drug,” Acosta said. The phenotyping suggests a strong genetic tendency – a biological basis for obesity.
“So it’s not just a way of shifting blame, but it’s also a way of explaining that there’s a reason you’re obese,” Acosta said. He tells people, “You’re not a failure.”
A more cost-effective treatment?
Targeting obesity treatment could also save on overall health care costs, Almandoz said. He estimated a cost of $1,400 per month “forever and ever semaglutide” or at least $1,400 per month for a 3-month trial to see if this drug works in a particular obese person.
“That’s a lot of money when you extrapolate that to the number of people who probably meet the treatment criteria,” he said. In total, 42% of Americans answer the CDC definition for obesity.
“You can imagine the potential cost if we had to provide anti-obesity therapies to everyone and we had to use the most effective class of drugs, over a thousand dollars a month, indefinitely,” Almandoz said. “Not that we shouldn’t treat everyone. That’s not the message I’m saying. But if we are looking at the return or value in terms of treating obesity in a resource-limited setting, it may be best to start with who is most likely to benefit.
How They Created Four Types of Obesity
Beginning in 2015, Acosta and his colleagues began comparing testing in people with normal weight versus obesity. They used artificial intelligence and machine learning to first classify obesity into 11 types. They realized that these many obesity types were inconvenient for doctors and obese people, so they combined them into four phenotypes.
“AI machine learning was followed, as I like to call it, by HI, or human intelligence,” he said.
The saliva test checks about 6,000 Genetic SNPs. SNPs are “single nucleotide polymorphisms” or changes in genes. Six thousand genetic changes might seem like a lot to check until you learn that people are walking around with between 5 and 6 million SNPs in their DNA.
The results are translated into a score that gives low or high risk for Hungry Gut or other types of obesity. “You can have all six thousand genetic mutations, or you can have zero,” Acosta said.
Following the soft launch of the Hungry Gut test in April, Phenomix plans to continue studying its saliva test in other types of obesity.
Acosta is not aware of any direct competitors to Phenomix, although this may change. “I think we’re the only diagnostics company in the business right now. But if it’s really a $14.8 billion market, we’re going to see a lot of diagnostic companies trying to do what we’re doing — if we’re successful,” he said.
A October 2022 Report from Polaris Market Research estimates that the global market for obesity treatment – drugs, surgery and all others – was around $14 billion in 2021. The same report predicts that the market will reach $32 billion by 2030.