General

I have to keep under a point for my job. I usually gain like crazy when I'm in my off season.

Implicit or explicit?

At say my retail job, I would say there's an implicit limit subject to individual capability, due to the physical nature of the job.

Retail is definitely a pain while gaining, I work in retail on the weekends and my ankles are killing me by the end of the day. And bending down to stock shelves is becoming more and more difficult

Fortunately, not me. That being the case for most jobs. I'm assuming you're asking about hard, explicit limits where actual numbers and measurements are used as a limit.

I suppose there might be an implicit limit in the sense of a sheer inability to perform the essential functions of the job. But, this number will vary from person and will also be very large. For most jobs, I doubt that'd be a problem unless you're in the top 0.5-1% "most heavy," and at that point you might be having problems in your personal life. At that point I'm talking well over 500-550, even 600+.

That said, there are a small number of jobs that could have such a limit, or where being beyond such a limit could cause hassle, and I'll list some examples.

One of the latest trends I've heard is of long haul truck drivers (company drivers) who have a neck circumference above a certain number, perhaps 18" or 18.5" being forced to use CPAP machines out of concerns over sleep apnea. Thing is, unless you really have sleep apnea it not only doesn't help but just causes a whole lot of hassles and problems. I've been told I snore, and I'm nowhere as large as that. Big deal. Anyway, this new requirement only increased the rate of churn for a job that already experiences extremely high rates of churn (the average new driver doesn't last beyond the first year). Why this is, is beyond the scope of this post.

I suppose anything which might require the wearing of a safety harness, perhaps because of working from great heights. An example of this would be radio tower technician, since someone has to be able to go up there to repair and replace the equipment up top. For a long time, those safety harnesses topped out at 250 lbs, which also had to include the weight of tools and replacement parts. Although I would expect safety harnesses with higher capacities have been introduced.

Anything that requires the use of an extension ladder. Last I saw, it's still possible to buy models that are only rated for 250 lbs, although models that support 400 lbs are far more common. Now that said, in the professional trades world, they're moving more towards bucket trucks and other lifts with railings, as those are considerably safer than ladders. Those lifts presumably have a much higher weight capacity.

Perhaps obviously, anything that involves modeling and acting, which are also the only occupations in the U.S. that are exempt from anti-racial discrimination laws, and are part of an extremely short list of exemptions from anti-age discrimination laws.

That said, I would be be interested to see what other jobs, if any might have explicit weight limits like this. I'm not really aware of very many. In other thread, I pointed out there was a 700+ lb owner of a tow truck business, and he was apparently able to perform those tasks just fine, despite the physical nature of the job.

Well, I'm just starting my weight gain journey. I'm still at a normal weight. But my destiny is to be a very obese person. I work in an office, so I could become excessively obese without any problems. Perhaps the only effect will be that they'll have to give me a bigger chair. (Which really turns me on.)