Yes, that is correct. I hate it that you are right.
I started weightwatchers in January. I was 234 pounds, and very insistent that I was fine riding at that weight. My horse has no problems with me, and my riding wasn't affected.
Now, three months later, I'm down to 203 pounds, and as much as I hate to admit it, riding is much easier for me. My horse is exactly the same as he was when I was heavier, I don't know how much he really cares about that 30 pounds, however there is a big difference in how I feel.
I can get on easier. Riding the spook is easier. I trotted for 10 minutes without getting winded, and would have kept going but my pony who is NOT in shape informed me that walking was a great idea. Barn chores are easier, cantering is less scary, and I'm less tippy.
I have noticed my balance is different, and I may need a few lessons to help me deal with the difference in how I can ride now, but overall I'm more confident and more secure.
I really, really hate it when you are right. Of course, by the time I lose the other 60 pounds I need to lose, I'll be the best rider in the world.
Well done! Congratulations! You are an inspiration...I am about to start a 30 day paleo-ish cleanse (doctor ordered and supervised) in an effort to pinpoint the reasons behind some gut issues I'm having. I've been told I should expect a 10 lb loss in the initial 30 days and I'd love it if it has a positive effect on my riding!