Sounds like he's going to have to make some hard decisions about what he really wants. If he really wants to take weight off and keep it off, he's going to have to learn to live with whole grains in place of white. Honestly, white flour and things made from it, white pastas, white rice -- those things will make him fat faster than fat will. They cause a spike in glucose that the body cannot process fast enough. And glucose that doesn't get used for fuel gets stored in the body as fat.
And he's going to have to branch out with the veggies. Visit the veggie forum for some ideas about ways to get carnivores interested in vegetables. For instance, I make a lasagne that uses eggplant slices in place of lasagne noodles, and my DH (who hates eggplant) and kids (ditto) love it! This will require some new skills and creativity on your part, but you don't have to be Betty Crocker!
Okay, so he likes potatoes. Switch to red skinned potatoes -- they have a lower glycemic index (measure of sugar and the body's insulin response) than brown skinned potatoes. Don't ask me why, they just do.
There's a brown rice pasta, made by the company Tinkyada, that is nearly identical in taste and flavor to white pasta. However, it's a whole grain pasta, which will increase his fiber intake, making him feel full quicker and helping his digestion, and it will not cause such an immediate glucose surge in his blood. They make spaghetti, swirls, macaroni, lasagne, etc.
You say he eats oatmeal for breakfast. Is it homemade, or is it the instant stuff? Because, again, that instant stuff is packed with sugar! Combine the sugar with the oats that have been pretty much stripped to a simple carb themselves, he's getting a nice, big glucose rush first thing in the morning. Fat headed straight to his ____ (insert wherever he gains first here).
Meatloaf is fine. Meat is not the issue. Even the saturated fat in meat is not the issue. It's the hydrogenated fats and rancid oils that make you fat!
(Along with sugar. Did I mention sugar?!?
) Portion control would be a good thing to institute here, but he can still eat those meats that he likes. You can even sneak stuff into his meat dishes -- I grate and puree zucchini and yellow squash, then add it to my spaghetti sauce, and my family is none the wiser. Makes it go farther, too. (I add it to meatloaf, too.) He needs to keep eating protiens and fats, in moderation, in order for him to 1) not be hungry all the time and 2) keep his body burning fat as fuel and 3) be able to use the vitamins and minerals he's ingesting.
How about fermented foods? Does he like sauerkraut? Fermented foods really, really make a difference in helping to stop my sugar cravings. In fact, they help to keep my appetite in check in general. And they have a ton of vitamins and minerals. And they help with digestion. They really are fantastic. If you could find some way to work fermented foods into his daily diet, it might really help with his desire to eat a lot of white starches and sugary things.
ETA: I wanted to add one more thing about sugar. Watch out for extra sugar in low-fat versions of things (like salad dressing, for example). They've mostly replaced the fat with more sugars, which will ... make you fat! AHA! Gotta love 'em.
And beware of high fructose corn syrup, too. It's everywhere, and there has been a lot of research to suggest that it causes obesity. More than sugar, even.