GNC on Youtube has a test about light vs heavy bike. They test two people on a ride, with and without extra weight to carry, I think it is 5kg. There is definitely an increase in time to complete the ride with extra weight.
That test was done by in-shape cyclists. We all know that we are our engine, so extra fat goes along with reduced efficiency. So expect lower strength, lower lung and heart capacity.
As for your mood, there are certainly links to that as well. I have heard that toxins build up when not excersizing, which tracks with what you have experienced.