This is kind of a spin off from the thread started by the trainer who worried how to tell her student she was too heavy for the school horse she wanted to ride.
There was a lot of dubious advice to overweight riders, but the advice to the trainer was just to be polite and upfront about it. Funnily enough I ust had the same conversation with my own trainer last night.
Long story short, my friend got hurt a few months ago and can’t ride - has been asking me to ride her horse. Horse is in full training with our trainer so I didn’t think my limited amateur skills would be too beneficial so I declined at the time and trainer agreed with me that it wasn’t a good idea.
Fast forward a few months, my friend is now nervous of her horse and wants as many other amateurs riding her so she can see that the horse is just fine with them (which she totally is). My horse has been lame for a week so again she’s been pushing me to ride her mare instead. When I brought it up to the trainer she acted very strange about it and clearly was against the idea but didn’t say why.
Last night the topic came up again and I could see my trainer really struggling with what to say. She was so worried about hurting my feeling and offending me but finally said I was too heavy to ride that horse.
Though it’s not what anyone wants to hear, I wasn’t offended in the slightest. I know how much I weigh and though I wouldn’t have thought it was an issue on this horse as she’s quite tall, the trainer knows her better than I do and explained why her height is not the only factor. If she thought I was such a crappy rider that I would ruin the horse in just a few rides, then I would have been really offended LOL. I know I’m fat but I’m pretty sure I’m not that terrible a rider 
Other than delaying telling me, here’s how I think the trainer handled it well. She was upfront and explained what about this horse’s confirmation and sensitivity made her not appropriate for me. She didn’t say I was too fat to ride, and made a point of confirming how well matched I am with my own horse. She didnt suggest there was anything wrong with me, offer health advice or tell me to lose weight. She kept it to the simple fact that I am too heavy for this particular horse.
I hope this helps that trainer who originally posted the question, and also any others in similar situations. Trainers / coaches / owners have to put their horse’s welfare first and riders have to make sure they are honest about their weight to be matched with a suitable horse. There are lots of appropriate horses out there for overweight riders (contrary to what some on this board will tell you).
