Have you considered that muscle atrophy might be part of your weight less as well? It sounds like you were bound to a hospital bed.
Though the part of the body that uses the most calories is in many respects the brain, and I know I think too much.
Also aware that my glicogen(probably spelling that wrong) levels can account for nearly 2 stone in my case - everybody different though and I'll admit due to my frame and size I'm not normal.
When I was doing competitive swimming and in peak form I could happily walk on the bottom of a swimming pool instead of being boyant and was due to muscle weighing more than fat. Just something I accept as normal too me.