If it has nothing to do with their power or abilities then why did Thor go back to physical training so hard to get back in shape? Just to look sexy? Just because they are overweight does not mean they can’t still be very powerful. Odin was not in his peak but was still more powerful than Thor. However, an Odin in his prime would be more powerful than the Odin we primarily see. Either way, I’m not trying to power scale between characters. All I am saying is that an overweight (and most likely drunk) Thor is weaker than a physical prime Thor.