I can see where junk food would cause depression and a whole host of other health problems. First lots of cheap starch and fat not enough fiber, protein and vitamins. If you look at folks that eat a lot of junk food you don't see muscle you see fat on them. So junk foods don't feed your muscle as much as your fat.
Being a man it's easy for me to change my physic by diet and exercise. I could look like Mr. Universe if I was that committed. Or if I didn't listen to my body I could end up like a small elephant. I worked out with a trainer which everyone should do if you want to work out. I was going for a more athletic stamina body which I was already working with. But I pushed it a little bit more and got pumped up my friends would tease me that I had better get a bra. I had more cleavage than some of the girls.
My legs which were massive already from walking 30 miles a day wheeling a 1,000 pound rack around it was brutal not many can do it. I'm surprised I could but only through mental conditioning was I able.

Well when I started to work my legs out and got to where they were rubbing because of the muscle time to stop.

But during this time I fed my muscle before and after I worked out, studied the science of building muscle. But when it came to junk food I would not eat much of the bread on my burgers.
During my workout time I noticed people who ate a lot of bread were fat. I cut bread pretty much out of my diet, it works if you want to lose weight or shape up. You get enough starches from what's out there already without adding more. I ate a lot more protein to feed the muscle I was building.
If you are big and fat you already have bulked up (that's the positive) in 6 months with training and diet you could lose weight and build muscle at the same time it just takes commitment and a good trainer to push you. I can't stress having a trainer as most people that start to work out don't know what they are doing 99%. So if you still want to eat burgers toss the bread.
