Move over, ketosis.

Over the years, we have all seen our fair share of diet trends, nutritional guidelines, and tips and tricks that are supposed to bring us happier, healthier lives. 

Some say not to eat after 11 p.m. Others say intermittent fasting is the way to go. But Bill Gates -- billionaire, investor, and Microsoft co-founder -- says the next diet breakthrough will have to do with your gut.

During a conversation at the 92nd Street Y -- a world class cultural and community center in New York City -- Gates said, "One thing that people are not expecting a breakthrough in that I'm quite optimistic we will get a breakthrough in is understanding nutrition."

"Why is it that it's not easy to have some sort of broader approach that lets us control our appetite?" Gates asked. "The microbiome looks like it will give us a solution there."

What is the microbiome? It's the community of viruses, bacteria, and fungi that live inside our stomachs, and it may be the key to solving worldwide malnourishment and obesity.

In both developed and underdeveloped countries, for example, good nutrition is a growing issue needing to be properly addressed. Worldwide, a little more than one in every five children under the age of 5 is not developing or growing in healthy ways due to poor nutrition or infections. And, at the same time, almost 6 percent are overweight. 

The result, according to Gates is, "they don't develop physically; they don't develop mentally."

Part of the reason so many young children are falling behind in development is because their microbiomes are not robust, lacking certain bacterial strains that allow these children to get the maximum amount of nutrients from the foods they eat. And fully grown adults have much to improve with their microbiomes too.

Ultimately, Gates believes that within the next 10 years, special microbial therapy (whether it is in the form of a probiotic food or therapy) will resolve these nutritional issues.

As we wait for this breakthrough to arrive, however, you can try eating fermented foods like kefir, kombucha, yogurt, and kimchi to strengthen your gut.