I think a large portion of the problem is our current lifestyles, as much as the food choices. Most of us spend 90% or more of our day sitting behind a desk and consider it a big exercise bonus when you take the stairs instead of the elevator twice a day. That, I think, is going to lead to even more health problems than diet.
There's also a problem with some of us in finding a form of exercise that we enjoy enough to stick with.
I'm one of those who will eat (within reason) what I *want* to eat. The key, though: IN MODERATION. I agree that portion sizes are way too big in most restaurants any more.
I'm also one of those guilty of not exercising for years and years. I've always *HATED* exercise with a passion, and would turn a grumblingly- deaf ear to any doctors who said essentially "suck it up and go to the gym".
No. I had better things to do with my time, life's too short to spend x hours at the gym doing something I hate and paying for it on top of that.
Excuse after excuse after excuse.
Finally, last Oct, I encountered a chiropractor and fitness therapist who took a different approach.
Him: Okay, you hate exercise. Why?
Me: I get bored STIFF after just 2 weeks and will drop it. Unless it's something like vacation where I'm hiking or things like that. If the exercise has more of a point or a goal than just "improving health", I enjoy it.
Him: So it sounds like you need something that stimulates the mind as well as the body?
Me: Exactly.
Him: Then let's find you something.
And find me something we did. Martial arts was the perfect exercise choice for me (even though it's *expensive*). Just as I start to get bored, I advance in level and there are new challenges. I have a goal to work for. I have a schedule to meet. And they focus on the mind almost as much as the body.
And as a consequence, I've lost 7-10 pounds (wavers depending on, yes, what I eat.

), toned up in areas that I've disliked about myself for years, gained in stamina, strength, flexibility and overall health.
And guess what: I'm *CRAVING* healthier foods. I'm actually *wanting* salads on occasion now instead of turning my nose up at them or eating them because I have to. I prefer Subway to McDondalds or Burger King. I've gone to diet cokes and more water rather than totally sugared drinks. And my sugar intake has gone down. And, I eat less because I'm satisfied earlier.
All because I finally found an exercise routine that I enjoy.
True, it's still not the perfect diet, but it's vastly better than what I used to do.
People like me don't care what we eat, and it doesn't matter about weight. In my case, I've never been more than 5 pounds over the "normal" weight for my height, but still, the philosophy is the same. I ate what I craved. I craved bad foods and didn't care they were bad. The trick to improving my nutrition was to improve the body's general health so that it craved better foods. And the trick (for me) to improving my body's general health was to find a form of exercise that not only do I enjoy, but I look forward to it every week.
Just the experiences of one person who ignores nutritional values.