Obviously we are not going to be comparing a fit triathlete to a coach potato that is 70 pounds heavier here. I am really interested in what happens to strength when a person gains weight yet keeps up the same activity level as before. Lets say a change in medication helps induce a weight gain of say 30 pounds over the course of a year. Would you get stronger in general? I figure your legs would just by carrying around the extra weight. It seems like lots of exercises use body weight as a benchmark.
Carrying more weight takes more energy, so you do get stronger. But since most people who gain weight gain much more fat than muscle, if you express a lift as percentage of body weight, it would be less.
More muscle mass= more strength potential. Those heavyweight Olympic champions aren’t "lightweights’. But more fat won’t help.
More fat helps in the sense that your muscles do more work to move a 280 pound load up a flight of stairs than they do to move a 175 pound load. People tend to get stronger as they gain weight, provided they do not live a sedentary life style. It is NOT a good strength building method, obviously. Adding fat only allows for strength gain in as much as it means you are always moving a heavier load around. I remember disussing this in kinesiology classes in college…the general point made by the professor was that leg and back muscles have to most to gain due to the added weight, and arms/shoulders not as much.
Bear in mind that as your weight goes up, the amount of weight you have to lift to match your bodyweight goes up too. So you might see an increase in absolute strength, but a decrease in relative strength.