By digesting our food and helping us get the maximum energy out of each calorie, getting new gut bacteria decreases our appetite and even changes the foods we crave.
Scientists are discovering changing a person’s gut bacteria transforms everything about them, including their weight.
In a recent study, scientists took the microbes from obese mice and lean mice and transferred them to normal-sized “germ-free” mice who had all their own bacteria wiped out with broad spectrum antibiotics.
The “germ free” mice who received microbes from obese mice became obese. The “germ-free” mice who received microbes from lean mice became lean.
Scientists have since repeated the experiment with microbes taken from humans and given to mice, with the same results.
Apparently, the gut microbes of the lean mice help them extract more nutrients from the same food the fat mice are eating, says Rob Knight, founder of the American Gut Project in a Ted Talk titled How our Microbes Make Us Who We Are
“Sometimes what’s going on is the microbes are helping them digest more efficiently, so they’re taking more energy from the same diet,” Knight says.
“But other times the microbes are actually affecting their behavior. They are eating more than a normal mouse.”
While mainstream medicine often tries to pawn off the blame for obesity on genetics, Knight says scientists are learning our gut bacteria are far more to blame than our genes.
“Today, we can tell whether you’re lean or obese, with 90 percent accuracy, just by looking at the microbes in your gut,” Knight says.
“We can only predict obesity with 60 percent accuracy using genetic testing.”
New frontiers in microbiology have made the waters a little muddy as to what we can blame on “genetics,” as 90 percent of the cells in our bodies and 99 percent of the genetic material (DNA) in our bodies are bacterial. Change the bacteria, and you change the whole person, scientists say.
Knight says most of our bacterial blueprint is determined in the first six months of life. Those who are born via c-section, formula-fed, or who received antibiotics in the first six months are significantly more likely to be obese later in life.
While our microbiome remains somewhat stable in adulthood, more and more animal experiments indicate we can change it up with antibiotics, probiotics, dietary changes and even fecal transplants.
In a project funded by the Gates Foundation, mice who got microbes from starving children in Malawi lost 30 percent of their body mass in just three weeks, Knight says. But their health was restored using the same peanut-butter-based supplement used for the children in the clinic.
But changing your microbiome isn’t as simple as taking a few bottles of probiotics and then resuming your normal lifestyle. If you want a certain type of gut bacteria to remain and flourish, you have to nurture it with the right types of food, aka prebiotics.
Recently a British professor completely transformed his gut flora by living and eating among the Hadza hunter-gatherers of Tanzania for just three days. But he began losing his new microbes when he returned to his normal diet in England.
High-quality protein, saturated fats and fermented vegetables are essential to a balanced gut biome, says Dr. Warren Peters, an epidemiologist, in another Ted Talk.
While Peters recommends avoiding refined carbs and sugars in general, he says artificial sweetners are particularly detrimental.
Marketed to diabetics and people trying to lose weight, these zero-calorie sweetners, transform the composition of the gut flora in a bad way.
“They gave artificial sweetner to thin mice and they became fat,” Peters said. “Then they gave other thin mice a fecal transplant from the fat mouse and they became obese. Why? Because artificial sweetner changes the microbiome.”
If you’re not into pills, there are plenty of other delicious ways to get good bacteria, including kombucha, water kefir, milk kefir, yogurt and fermented veggies.