At this point, it is well established that a lot of health starts in the gut. But, scientists are still unraveling how our microbiomes control so much of our well-being. A new study has found that eating a large amount of the fiber that feeds the microbes in the gut appears to lower the brain’s reward response to high-calorie foods.
Prebiotics are the fiber that feeds the gut. A study gave overweight adults 30 grams of inulin — the prebiotic in chicory root — daily for two weeks. The researchers showed the participants photos of food during MRI scans, asked them what food they wanted most and then had them eat their desired dish after the scan. They performed the MRI scans four times: before the prebiotic treatment, after people had taken inulin for two weeks, then again before and after a placebo phase. The placebo they had people take had the same calories as inulin but none of the prebiotics.
After taking inulin, people’s reward centers in their brains had lower activity when looking at high-calorie foods. The change in their brains was reflected in the types of bacteria in their guts. Their microbiomes shifted over the course of two weeks.
Earlier animal studies had found a connection between prebiotics and turning off cravings. However, we always urge caution when reading too much into animal studies. Not everything seen in animal models is true for human health.
Megan Hilbert, a registered dietitian specializing in gut health nutrition, said, “Animal studies have found that prebiotics and probiotics can alter our cravings, metabolism and mental well-being, so seeing findings like this in human literature is an important next step in understanding how we can modulate the gut to improve human health.”
High-fat and high-sugar foods activate the reward center of the brain. But this study shows that prebiotics can change that. So much of what we call “willpower” is ignoring cues your brain is giving you. This study shows we might be able to retrain our brains through our gut to be less interested in high-calorie foods. It could be a huge step forward in making weight management easier.
A follow-up study has begun. A six-month trial is looking at how long-term high does of inulin will impact food choices, brain function and weight in people who are obese or overweight.
We write so much about how fiber benefits weight loss by filling you up. And, of course, fiber can help blood sugar by slowing the absorption of sugar. However, this study shows that fiber in the form of prebiotics may help retrain the brain to make better food choices. That could make weight management a more easily achievable task for those who struggle with it.