I have thousands of miles on my old Paramount Series 5, but got to an age where drop bars were just too uncomfortable. Nice for racing, but kind of pointless if you're looking for comfort on a bike that you're using for exercise and calorie burning, not speed.

Consider one of the hybrid-type bikes like the Trek FX series.

Weight loss...calorie burning helps, but as long as you can eat more calories in 5 minutes (think glazed donut) than you can burn in an hour on the bike....weight loss is going to be about calorie intake, not calorie burning.