Try getting into biking. I burn 1500-2000 calories (I’m not a small dude) in like 2 hours of road cycling. It’s relatively easy on the body compared to running as a bonus.
Oh also another thing to check is weather your fitness tracker is reporting active calories or total calories burned. If it is the second one it’s giving you a feel-good number that includes calories you would have burned just by sitting on the couch staying alive. If your fitness tracker isn’t calculating a BMR you can estimate your Base Metabolic Rate fairly accurately with a calculator like this one.
Are you sure about that number?
According to my tracker, I burn about 1000kcal per 60km, and I’m an normal dude. You probably won’t average 50km/h over 2h or something.
Given weight and road grade plays a role, they don’t need to average 50km/h necessarily. Still, 1kcal/hour seems quite intense for a regular exercise for me, but similarly large professional-level endurance athletes probably burn far more during serious training or competitions. 750kcal/hr seems manageable to me as a non-athletic person (supposedly I’ve burned 2340 calories over 2.7hours once… but I was totally wiped out afterwards IIRC). 1K/hr isn’t something I could maintain for more than about 1.5 hours even on the best of days.