The Biggest Loser trainer Bob Harper came perilously close to death when he suffered a heart attack in February 2017. The shocking health scare was seemingly unimaginable for Harper, who spent 18 seasons training contestants on The Biggest Loser to make their physical and emotional health a priority.

For years, Bob Harper and Jillian Michaels appeared to have great chemistry onscreen while filming "The Biggest Loser" together. But a new docuseries about the NBC weight-loss competition has fans wondering if the dynamic duo actually got along in real life.