I can’t lose weight, I can only lose mass. Weight is a function of the gravity well I am in.
Not so. F = ma. Your weight is proportional to your mass (and the local depth of your gravity well. Lose mass and yes, my friend, you will indeed lose weight. (or just find a shallower well, but put preferably with an oxygen atmosphere, job opportunities, and knowing you, girls!)
You could telecommute from a smaller planet.
And on Mars you could bench press 8 pounds of mass.