I'd like to see those studies. As far as too many green vegetables being bad for you, that's theoretical and not real-world. You'd have to only eat spinach with no other vegetables, and you'd have to eat it every day in large quantities, and then it could possibly negatively affect your ability to absorb calcium. I read one story a while ago about a woman who had no health insurance (important because this never would have happened in a decent country filled with decent people holding decent values) suffering from diabetes. She had read Bok Choy helped alleviate symptoms. She ate 3 pounds of raw bok choy a day and ended up in the hospital. You'd have to do something pretty f'ing crazy like that in order to have your health be negatively impacted by vegetables.
Also, regarding obesity and lack of exercise causing cancer...have you read the latest studies? They are very compelling. They are showing that it's fat in your liver that elevates you risk for all of these diseases including cancer. And that thin people who don't exercise have fatty livers, and fat people who do exercise don't. Obese people who exercise regularly do not have any higher risk for early death. Thin people who do not exercise do have a higher risk of an early death. It has little to do with weight, other than the obvious correlation that the more you exercise the less likely you are to be obese. It's all exercise - cardio. Cardio is everything. Brain health, heart health, lower risk of cancer, it's everything. So the bottom line is even if you can't lose weight when you exercise (maybe you eat more because you're hungrier, whatever) doesn't matter. Just Do It really is the key.
I think it's good news for people who struggle to lose weight, can't, and just give up. Don't give up if you want to live. It really is about your health not about your looks.