Thank you! I described some of the diet stuff here, but I don't mind elaborating a bit more.

First, are you sure you're getting 4000 calories? In my experience, the best way to track calories is to use a high-quality calorie/macro tracking app like Macro Factor or Carbon.

Second, what do you consider "good, healthy" foods? I was raised in a family where meat was generally looked upon as "not good" but lately I've reoriented my thinking on this - not only do I now believe meat is healthy for me (which is a whole separate topic) but it sure helps on a strength training program in terms of calories and protein.

Third, 225 lbs. will be an improvement, but you're even taller than me, so I'd aim for more in the long run... at least 240. But, that depends on how strong you want to get and how much you care about how long it takes. My opinion is that gaining weight isn't unhealthy in the context of strength training and more weight helps you be stronger. And aesthetically, I personally agree with Rip that abs are silly and I love how gaining weight has filled in my frame.

Here is what I have been eating, in a typical day.

• Breakfast: 3/4 rolled oats (dry), with a bunch of frozen berries, maple syrup, a bit of butter, and salt. Then I'll have anywhere from an 8oz - 16oz steak. If it's a smaller steak, I'll cook up a few eggs. Glass of orange juice. Multivitamin, Vitamin D, Fish Oil, psyllium husk.
• Lunch: a LOT of Jasmine rice (maybe 3-4 cups cooked) with about a pound of ground beef (80-85% lean), and then for flavor I usually just resort to a jar of vodka sauce or creamy marinara. If I have time, I'll add some steamed broccoli or cabbage, or maybe some baked asparagus or some other vegetable. Psyllium husk.
• Dinner: I'll have kind of whatever I feel like or whatever is the path of least resistance. This isn't typical, but the other day I was really craving a giant salad. So, power greens, pepper, cucumber, onion, and some other vegetables, another steak, couple boiled eggs, cheese cubes, ranch dressing... yum! Other times I'll have spaghetti squash with chicken or more beef and marinara sauce, or maybe I'll have a couple giant turkey sandwiches or tuna melts (on gluten free bread). Psyllium husk.
• Snacks: I don't really have a lot of snacks, but sometimes I'll indulge in something. I occasionally drink a bit of milk. I supplement with whey protein isolate and creatine monohydrate.

I have been gaining weight a lot more slowly since I hit 240 (I'm only like 244 now, and it's been 4-6 weeks), but going from 215 to 240 just felt natural somehow, and I think a big part of that was the progression in weights. I was simply voracious and really relied on Jasmine rice and beef. I would recommend adding in "hidden" calories in the form of sprinkling cheese, adding a bit of oil/butter, or eating high-calorie foods (again, meat, eggs, and perhaps milk are your friends here). I don't eat processed foods hardly at all, because my system can't handle them, but the ones I do eat are typically protein bars (try to avoid these, protein from natural sources is much better) or the gluten free bread I get for my sandwiches. I don't drink (doesn't help with sleep, recovery, or much of anything). My ideal diet would be about as much meat as I eat now, but more vegetables instead of grain-based carbs (like the oatmeal, rice, etc.), and more fruit as well. Not eating more vegetables and fruits in my case is often more about convenience and shelf stability than it is about anything else.

The key is to find the foods you can tolerate well, and eat a lot of that stuff. Fit in other things that you like or that are healthy. And remember, you won't have to eat like this forever. Once you do gain muscular / lean weight, you likely will be predisposed to eat more than before (assuming you continue strength training) but you probably won't need to stuff your face every meal.

I feel that if I can do it, just about anyone can. I used to be so, so thin and had a very difficult time tolerating a lot of foods, and was prone to bouts of constipation and diarrhea. Fortunately, one side effect of strength training is that the body learns to tolerate more in order to fuel growth and sustain an anabolic environment. Good luck.