Endurance athletes like Michael Phelps, here at the 2012 U.S. Olympic Swimming Team Trials in Omaha, can easily burn off stacks of pancakes. Jamie Squire/Getty Images hide caption

itoggle caption Jamie Squire/Getty Images

A New York subway ad from Zevia soda company, supporting the mayor's ban. Jason Decrow/Invision for Zevia/AP Images hide caption

itoggle caption Jason Decrow/Invision for Zevia/AP Images

Bacteroides species are some of the most common bacteria in the human gut. Enviornmental Health Perspectives hide caption

itoggle caption Enviornmental Health Perspectives