Well, I dunno. Bulking up with chalk, sawdust, or even white lead. Bit of arsenic to make everything a pretty green colour. If you've got plumbing, it will literally be plumbum, lead piping. No guarantees the water is clean and potable, either. Cholera, typhoid, etc...
The diet might be pretty monotonous. Depending on which bit of history you're looking at, there might not be much meat, unless you're rich, in which case it's mostly meat. Expensive spices were used in part to cover the taste of rotting meat. Risks of salmonella, listeria, botulism...
If you can't afford meat, then peas and beans. Seasonal veg - it's no coincidence that Lent, a time of fasting, coincides with the time of least food availability in the northern hemisphere. You could poach game and get meat that way, but you're risking mantraps up to the late 1820s, and transportation. 1 in 3 harvests failed during the 17th century. 1840s Ireland had the potato famine. People starved.
This week, I've had bananas, citrus, chocolate, peanuts, and probably other things we don't produce here. I do try to eat fairly seasonally and I try to buy British (brought up on a farm,) but I am glad I'm not totally reliant on that, and when I do get food in,it's fresh because it's been refrigerated most of the time since it was picked.
I'm in favour of eating less processed food, but I don't really want to go back to any earlier culinary period, though. I like the choice and freshness being available to me.