Some doctors say it. Many social media diet and fitness “experts” swear it’s the truth. But the idea that obesity is caused only by consuming more calories than you burn is a myth, according to UT Health San Antonio Marzieh Salehi, M.D.
“I have to actually have this discussion with my patients, because they’ve been told this for years and years, and they are ready to be yelled at again,” Salehi said. “They walk into my clinic, and I just say no, no, no. It's not one calorie in, one calorie out. That dynamic is absolutely not true.”
Salehi should know. She’s an endocrinologist and a professor of medicine with the Joe R. and Teresa Lozano Long School of Medicine who is an expert in obesity, diabetes, and polycystic ovary syndrome, a disorder that can cause obesity and infertility. She does what is known as translational research, which is when you apply the results of laboratory research to actual patients.
Professor of Medicine
Department of Medicine, Division of Diabetes
The University of Texas Health Science Center at San Antonio
“Part of my lab work over the 20 years has been understanding the cross communication between the guts and other organs,” Salehi said.
That communication starts before you even open your mouth.
“We know that by the time that you're smelling, you're looking at the food, and then you're swallowing the food … a lot of signals being triggered, which start affecting different organs, such as muscles, fat, liver, brain.”
This communication — or sometimes miscommunication — impacts how we metabolize nutrients. But the thing is, we don’t know exactly how. Salehi hopes to learn more about that by studying a population that is at greater risk of developing obesity and diabetes, people with spinal cord injuries.
“We have preliminary data showing that they do have problems with the cross-communication. So whether it's a neural signal which is affected, or some of the gut hormones are affected, we don't know.”
Salehi’s clinical trial will be the first to study the impact of semaglutide — the active ingredient in Ozempic and Wegovy — on the regulation of blood glucose levels in people with spinal cord injury and type 2 diabetes.
Drugs like semaglutide have changed the game for people with obesity around the world, but scientists don’t know exactly how it impacts this communication between “guts and other organs.” Salehi is digging in to try and figure that out, because that could lead to specialized treatments for so many different metabolic conditions.
“For example, we have patients that have fatty liver, but they do not have diabetes. We have people with extremely high glucose numbers, but don't have kidney function abnormality,” Salehi said. “We could change the recipe for individual people — something we call precision medicine — depending on what signal we need to target the outcome.”
But before that, Salehi’s research may change the game for people with diabetes and spinal cord injury. The study is being funded with $3 million from the National Institutes of Health.
Science & Medicine is a collaboration between TPR and The University of Texas Health Science Center at San Antonio that explores how scientific discovery in San Antonio advances the way medicine is practiced everywhere.
