You truly don't need a meal program. The best thing to do is eliminate from the groceries/house the things that make us overweight. Avoid processed/fast foods. They tend to be loaded with additives (MSG is in nearly everything, sometimes labeled as "spice" or "flavoring"), which make them tasty and addictive, and more research is showing that the additives also make us gain weight. Sugary drinks (soda - even diet, JUICE, punch, etc), processed grains (white flour, white pasta, white bread - even "wheat bread" is just white flour that hasn't been bleached - white rice, quick oats, etc.) If it is really whole grain, it will say "100% whole grain". A lot of GM cereals now say "made with whole grain", which means they put a little in it, but it's not 100% whole grain unless it says that (like Shredded Wheat). Also, cereals tend to be bad, as they are loaded with more SALT than potato chips, and sugar. The problem is that refined grains have had all the fiber and nutrients stripped from them. By law they have to add some vitamins back in, because otherwise it's nothing but calories. So when it says "fortified", that means it's been added back in. Just eat the real deal in the first place, and you'll get those nutrients.
There are homemade playdo recipes that just call for white flour and salt, which is what so many prepared foods/snacks are made of. Not nutritious at all. Also, this is unnatural, so it raises the blood sugar unnaturally, which raises insulin, which makes the blood sugar crash, and ultimately makes us fat.
So what to eat then? Regardless of what some people say, in my opinion eggs are just about a perfect food. Our bodies make cholesterol, which has a number of important jobs in our bodies, including providing a barrier that protects the brain. Yes, eggs have cholesterol, but have been found to be pretty darn healthy for us. So, eggs and fruit (not juice) and maybe some whole wheat toast for breakfast. I know some people think pancakes are fattening, but I've made them from scratch my whole life and if you use whole grain flour (wheat or buckwheat), and milk, eggs, and maybe half as much oil as the recipe calls for, and omit the sugar, they are pretty healthy in my opinion. Of course, only use about a teaspoon of butter and/or syrup/jam, just enough to give it the flavor. Whole grain oats are great for breakfast, too, just watch how much sugar goes in.
For dinners, anything that you make is going to be better than anything processed. When you go grocery shopping, just stay along the perimeter of the store (dairy, meat, produce) and you'll do fine. If you work - or not, the crock pot makes wonderful pot roasts with vegies. There's nothing wrong with that, just try to use lean cuts of meat. Or chicken dishes, or anything made with legumes (beans). Split pea soup is really easy, and people are always surprised at how yummy it is. I put a pinch of meat for flavoring (sausage, ham, etc) and some onions, carrots and garlic, salt and pepper, and my small children and hubby love it. It cooks in about 40 minutes (longer in the crock pot), and doesn't need to soak. Chile (beans, lean meat, tomatoes) is a great food, and I like it over chopped lettuce. Fried rice (easy to make yourself) from brown rice, with a little bit of oil, a couple of eggs, a little soy sauce, and vegies is a simple, quick dish. I often make a big pot of rice, then keep some in the fridge ready to use (it doesn't keep too long, maybe a week). I've replaced pasta with rice a lot (like spaghetti - rice is just as good with sauce/lean meat). There are bean recipe books (look on amazon), and crock pot books, etc.
And, just don't buy the true junk food like chips, cookies, crackers, cakes, desserts. You don't even have to say why. If asked, I just tell my kids it's junk food. There are so many opportunities to eat it anyway away from home - that's enough.
And, milk in moderation. A former coworker of mine gained 20 pounds in about a month as soon as she found out she was pregnant because she started guzzling whole milk. The doctor told her to knock it off. Funny how people think they can eat whatever they want just because they are pregnant, then wonder why they pack on 50 pounds, and can't lose it after baby is born. Anyway, no more than 3 cups of milk a day for your son. It's important to learn to drink water.
For snacks, fruit, nuts (in moderation), vegies, sandwiches with whole wheat bread, just a smidge of mayo, or for PB a thin layer of PB, etc.
If you ever glance in the cart of a really obese person at the grocery store, it's usually full of what not to eat: sugary drinks, chips, cookies, "snack foods", etc.
Also, it is almost never recommended that children actually lose weight. It's too risky when they are developing bones and such. It's much better to eat properly and get exercise so that he develops muscle, which then makes him slimmer, without actually losing weight. If he did happen to lose a few pounds in the process (without restricting HEALTHY foods), that would be ok.
Best of luck to you! I have a degree in nutrition, so kind of got long winded here.