The Rippetoe stuff should generally be applied such that you gradually increase your intake until you're putting on enough weight, and back off if you're gaining fat too quickly. And for the majority of Rippetoe's target audience, that is young skinny guys, getting enough calories is more important than the right calories.

I'm curious as to whether you just started drinking a gallon of milk every day from the get go? Because I imagine that adding ~2800 kCal to your maintenance diet would tend to pile on rather more fat than usual.

Also I'd assume that the average HNer could put together a diet that's pretty reasonable with minimal preparation, however, here's a few pointers I've followed...

General diet guidelines:

a) For optimal health, the fewer calories you eat without starving or failing to satisfy nutritional requirements the better (ie caloric restriction). Hence eating to gain weight, even muscle, probably necessitates a sub-optimal strategy.

b) Body transformation is made in the kitchen, not the gym. If you eat less than maintenance calories you'll lose weight, more than maintenance calories you'll gain weight and make better strength gains. Heavy weightlifting is a must to begin with, but your work in the kitchen determines your outcome.

c) Don't eat processed food. It's normally High GI and full of crap [1].

d) Eat six small meals each day, at even intervals. This seems to work better than three large meals. Of course, if you're bulking, then you'll be eating six large meals each day and feeling sick most of the time.

e) Eat lots of non-starchy vegetables and some fruit. Vegetables implies things like broccoli and spinach. For fruit aim for things like berries. More vegetables than fruit because you can overdo the fructose.

f) Eat plenty of fish, nuts, avocadoes and other healthy fats. If you need to boost your calories further a shot (30 mL) of olive oil is ~ 250 kCal and only takes a minute.

g) Eat fewer carbs, and make sure they're low GI. Hence things like lentils, brown rice, quinoa, etc. Eat carbs early in the day as they seem to give you more energy.

h) Another fine protein source is skinless chicken breasts. I boil mine and throw away the fat that floats to the top. Eggs [2] can also provide lots of protein.

i) Full fat milk is awesome for gaining weight as it is quick to drink and provides quick calories.

j) Diets continue in perpetuity. It's like showering or brushing your teeth. You don't brush your teeth twelve times a day for a month then say "well, that's taken care of" and never brush them again.

k) Post workout (for all the good post workout nutrition does) drink something with carbs and protein. I generally go for a liter of milk.

l) If you're trying to reduce your caloric intake, replace food with things that are calorically sparse. If you eat a big salad [3] before each meal you'll reduce the number of calories you can get through without feeling hungry.

m) If you're trying to eat more and can't get through the food, buy a really good blender and drink as much as possible.

[1] I'd chiefly be worried about salt and high-fructose corn syrup. A lot of the threatening looking stuff on the label isn't, but it's a pain in the ass to figure that out.

[2] I'm not sure whether they're good or bad for you today.

[3] With no dressing or something with minimal calories if you aren't hard enough.

Potentially many of these could be debated as nutrition is a bit of a clusterfuck of contradictory information, but I'm reasonably confident in them.