Lightweight strongman classes are usually <90kg or under <105kg. Here are the events and weights for the Englands strongest man qualifier to give you an idea of what you'll be up against. It was an under 90kg comp:
If you really want to give it a try then I say gain as much weight as you can afford to for your martial art and try and get strong as hell for your bodyweight. If you can, try and train some events to get an idea of how far you need to come to be strong enough to participate.
The LW division (Under 231.5 lbs) does have subcategories:
LW Open / 231.5 lbs Class <200 lbs Class <175 lbs Class
Generally you will see these weight divisions at most larger (regional) contests, and sometimes at smaller events although they tend to consolidate to make things easier.
There are national championships for all weight classes including 175, 200, and 231.
In terms of being able to handle the weights, depending on your strength levels it is still possible to train with strongman implements and perhaps even compete at 150 lbs - I have seen a few guys out there at that size previously.
If you are just looking for a sport to give you a chance to push yourself and to try something new for training then it would be a great idea. If you are looking for a sport where you will be dominant then you may want to look to something with a different weight class breakdown (such as powerlifting).
Strongman is a lot of fun even if you are not competing.
Thanks for the replies. I don't mind putting on some weight since it won't be fat or anything but 50lbs is a lot of weight. Good to know there are these somewhat smaller classes I could try and aim for.
I just dropped to ~175 from 205 and I remain competive. There are some contests with a 200lb weight class, and I'm usually at the top in these contests, and others with a 231lb weight class, and even in these I'm competitive. Strongman isn't based on weight, it's based on weight moved.
I will say that losing that weight, while I kept my strength, totally fucked up my stone loading because I don't have a belly to wedge.
There is an athlete in New Jersey who I used to train with and he weights between 175-185 lbs yet is an outstanding 200 lbs class competitor who is probably top 3 in the nation when healthy. He is also a great athlete and typically wins because he has many of the important tools in strongman - grip strength, technique, and conditioning.
One guy named Max used to compete at around 150 lbs and was able to complete most of the events. He posts a lot on Youtube but haven't heard much from him lately.
I would say to give it a try and see what you can do. Worst case you decide that it is just something to include in your training once in a while to mix things up or you can come back to the sport later once you have more time in the gym. When I first started training I was 150-155 lbs and now years later walk around comfortably at 225 lbs (same height, unfortunately).
Thanks I guess its just slightly daunting where I'm currently at in my training but I want to push myself to get to the point I can try to enter. I found a website with some listings and looks like Novice might be a good place to start but those numbers are well out of my range at this point. I'm currently deadlifting 250 but I only really started lifting about 5 months ago and deadlifting about 3 weeks ago. I'm not sure how it will work because I'm planning on applying to be an Officer in the Marine Corps but if possible I'm hoping to continue training and maybe enter my first novice competition late next year, think I can make it to those numbers if I push myself - and that is what its all about.