My experience was that I was
scheduled 12 hours a day, the reality is that we all commuted 1h both ways and turnover often took 30-45 minutes. We were bussed in, and we arrived 15-20 minutes early. To put the final little bit in, we also had to commute to the bus depot. Whatever extraneous time I had was spent in the shower.
While I did manage to eat decently I also had the benefit of years of working in kitchens and I opted for vegetarianism years prior so I had to delve into a novel culinary discipline which served to broaden my horizons both in what I considered a meal, and what I was willing to eat, and how I was willing to eat. Looking at the rest of the cohort: yeah, it was bad. A lot of industries we interfaced with had a lot of very evident cases of poor diet. I expect among the whole the chronically single and childless were the few that could manage their health in the context of that schedule or any modern American regime, really.
Beyond diet it's physically taxing, especially considering that my industry, and every industry touching it worked some variation of swing shifts and if not that, 24/7 on-call. That alone is extremely taxing and has prolific long-term implications. Alcohol and drug abuse are commonplace, whether licit or illicit substances. And there's a huge emotional layer to it as well, if that isn't obvious. Mind you these are the people paid by the companies that keep your lights and heat on, transport all your food and fuel...
But even outside of that extreme edge case the other jobs I've had can have their own sets of challenges. It's not always overeating that gets you, but undereating is a hazard as well. And workplace injuries are not so avoidable as the institutions like to profess. If you're pressured, your peers are pressured, your customers are pressured, etc... the culture itself becomes go fast or die trying — they'll tell you to work safe but God forbid if you do you'll be punished for it, ask me how I know. And that's without factoring in RSIs, which in some occupations are virtually inextricable.