Because working out, alone, is not the solution. You could work out all day and still not lose a pound. Plenty of studies have shown this.

Moreover, have you ever tried to work out at 450 lbs? No? It is an immense effort, often literally impossible for most people at that weight, and the best they can manage is a walk around the block before their cardio can’t keep up.

What then?

See above, where I reminded people (which includes you) that things are rarely binary.