Some 749 million people worldwide go hungry every night, and almost two billion are overweight or obese. Our food system contributes substantially to greenhouse gas emissions. We overuse antibiotics.

It can be pretty depressing on this planet sometimes, when you think about it.

But Alessandro Demaio, a 30-year-old Australian whose medical work has taken him from Cambodia to Copenhagen, thinks we can solve these outsized challenges by connecting people through food and fun. He’s been a global health fellow at Harvard and in 2013 co-founded NCDFREE, a worldwide social movement for global health. Now he’s the mastermind behind festival21: a free, all-day celebration and festival on rethinking the future through food in Melbourne on December 11. (National Geographic is a partner.)

Before he settled into his latest