What if you could eat whatever you want and never worry about your waistline?
It may not be as far-fetched as it sounds.
Researchers at the University of Colorado Boulder may have found the mechanisms for a groundbreaking vaccine that could help people keep their weight in check by tapping into the power of healthy bacteria.
In a study published this week in the journal Brain, Behavior and Immunity, mice injected with a micro-organism found in cow’s milk and soil were essentially immune to the weight gain typically caused by a high-fat, high-sugar diet.
“What is so striking about this study is that we saw a complete prevention of diet-related weight gain in these animals,” said senior author Christopher Lowry, professor of integrative physiology.
“This suggests that exposure to beneficial bacteria can protect us against some of the negative health outcomes of the typical Western diet.”
Happy accidents: from stress to weight loss
Lowry didn’t set out to create a weight loss vaccine.
In earlier studies, he discovered that Mycobacterium vaccae (M. vaccae), a microorganism found in soil and cow’s milk, could reduce stress-induced inflammation in mice. This led him to explore the idea of a “stress vaccine” made from dirt-dwelling bacteria.
For the new study, Lowry and his team tested whether M. vaccae could also help counter the brain inflammation and anxiety that often accompany a poor diet.
One group of adolescent mice was fed a healthy diet, while the other indulged in the rodent equivalent of Big Macs and fries for 10 weeks. Half of each group also received weekly injections of M. vaccae.
By the end of the study, the untreated junk-food-only group had gained 16% more weight than the healthy eaters.
They had also accumulated significantly more visceral fat, the “bad” fat that wraps around organs and raises the risk of heart disease and diabetes.
But here’s the real kicker: The junk food group that received the M. vaccae injections didn’t gain extra weight. In fact, they even had less visceral fat than the healthy eaters by the study’s end.
The study is the latest in a growing body of evidence on the benefits of healthy forms of bacteria known as “old friends,” which evolved alongside humans but have fallen to the wayside in our modern, sanitized world.
“As we have lost contact with these old friends that served to regulate our immune system and suppress inappropriate inflammation, it has put us at higher risk for inflammatory diseases,” said Lowry.
Chronic inflammation is a major health threat. It can wreak havoc on healthy cells, tissues and organs, and is often a precursor to serious conditions such as Type 2 diabetes, cancer and heart disease.
It has also been linked to an imbalance in the gut microbiome, which aids in digestion, destroys harmful bacteria and helps control your immune system.
What’s next?
The idea of a vaccine to fight weight gain may sound like science fiction, but if it works, it could be the next big thing in medicine.
Further study is needed to understand how M. vaccae prevents weight gain and whether the same effects can be replicated in humans. Researchers suspect it may work by reducing inflammation, improving fat tissue health and boosting metabolism.
If proven effective, the M. vaccae shot could offer a new weight-loss solution for those battling America’s obesity crisis, which affects an estimated 40% of adults and 20% of children, according to federal data.
That could be especially valuable as many Americans continue to struggle with accessing next-generation weight loss drugs like Ozempic and Wegovy, due to barriers such as high costs and supply chain issues. Unlike the M. vaccae shot, these medications work by mimicking a natural hormone in the body that signals to the brain you’re full, helping to curb your appetite.
For now, Lowry suggests that the best way to boost your exposure to “good” bacteria is to spend time in nature — whether it’s working in the garden, taking a walk or relaxing outdoors. You should also eat lots of fresh vegetables, which soak up healthy microbes from the soil.
And don’t forget: Much of the food sold in grocery stores is junk. Studies have found that roughly 70% of the items available in checkout aisles are unhealthy, with the majority being candy, sugary beverages and salty snacks.
