Distance covered, rather than speed, is the major factor in calories burned. A very rough guide is that you burn about 100 calories per mile walked, with a 5% incline burning 65% more than this.
You don't mention the specific incline , but 400 calories in an hour does not seem unreasonable on this basis.
What you do in terms of exercise is less important than just that you do it regularly. And if walking is something you can do to build up a habit of regular exercise, then that is what you should do.
Perhaps over time you can slowly increase the speed to 2.6, 2.7, etc mph to gradually increase the intensity.
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.
| current weight: 178.0