That experiment has been done ad nauseam ... as in, I am nauseated by how much weight I have gained.

Eighty pounds ago I could climb any hill anywhere at any time with a fully loaded touring bike----I might not have always been fast, but I used to be able to spin 120-130 rpm all day long, and my touring bikes had triples and endless gearing it seemed.

Now I can barely haul myself up Any hill, no matter the gearing. I have gained about what my full touring load used to weigh ... but in losing fitness in order to gain weight more quickly, I gave up lung capacity, cardio capacity (to almost a terminal level) and strength. I probably couldn't climb a mile-long five-percent hill in 22x36 right now .... i'd pass out half way up from oxygen debt, or insufficient blood to the brain and lungs, or I would just fall over because of no more strength in the muscles.

Sorry I didn't keep a log of what I lost with ever ten pounds gained.

In the interest of science, I guess you should repeat my experiment to see if my results are valid ... but get good health insurance first.