Im 28, 5'11 and weigh 142.3kg (313lbs).
Ive tried many different types of diet/lifestyle changes but i find my commitment is my biggest down fall. Breakfast and lunch are fine and im in the construction industry so i get plenty of movement there ( i also have started doing a program from here). But dinner is where i lack will power
Commitment is pretty much the only reason anybody fails at fitness goals (with some exceptions)
For most people, there isn't any reason they CAN'T lose weight, or gain muscle. We all must follow the laws of physics.
That being said, finding the kind of program that you're personally more likely to stick to is pretty difficult.
You're a big guy, your body wants to maintain that. Normal.
Do you use myfitnesspal or any calorie counting app? You don't really have to starve yourself to see progress. It takes some getting used to, and some commitment to getting used to it, but it's a great tool. Don't get frustrated if you don't meet your goals in the first few weeks and end up going over your calorie allowance. You gotta get used to the system.
Substitute more vegetables for everything. You can eat buckets of vegetables, they're not loaded with calories. Next are fruits, they have more calories but can really help with cravings for even worse junk food.
I find avoiding carbs helps me cut a lot of calories.
Prepare snacks, pack em in containers to take with you, like chopped fruits and vegetables, when you get cravings, eat something, but try to eat your healthy substitutes first.
If you don't deprive yourself too much during the day, maybe dinnertime will be easier.
Also, cutting simple sugars (like soda or candy or pastries) is really hard, like quitting smoking... But if you can manage to do it it gets much easier after a couple days.
Not sure if any of that is helpful. Just remember there's no actual reason you can't do this. Stick with it, and remember that also includes sticking with trying again after you fail to stick with it.