I'm not even a little bit literate on the field of nutritionism, but I do have an opinion on the matter of obesity vs. exercise/food intake for personal experience.
Perhaps I had bad luck with my nutritionist, or perhaps I'm too inflexible regarding what I eat, but my one and only consultation with a nutritionist was a disaster. And now I don't trust the profession at all.
Starting with the definition of "obese". She started by weighing me and measuring my height and called me obese.
I'm technically obese because my weight-height ratio is above some predefined standards.
Now I know I don't have a perfect "Men's Health" body. I do know I have some excess fat.
The thing is: I go to the gym 3/4x a week, always to have exercises and assisted classes that are directed at loosing body fat (or the technically inaccurate term "muscle toning").
I exclusively do exercises that consist in low charge with lots of repetitions like doing cardio, TRX and Body Pump.
During my entire lifetime, I never did any exercise to increase my muscle volume (before the gym, I did waterpolo)... but life isn't really fair, we all have a different DNA.. and I just happen to end up with large muscles. And a proportionally large weight. Arms/shoulders won't fit in every shirt even though the abdomen part is loose and legs won't fit in all pants where the waist is good.
Plus, whenever I'm sick and stop going to the gym for more than a week, I start losing weight (despite eating a lot more because I'm bored at home).
I practically only eat salads at lunch during the week and at night we make sure not to over-eat (I suffer from insomnia so over-eating at dinner is forbidden for me, when I have to get up early the next day). I do one or two "excess meals" a week during the weekend, maybe some popcorn in the movies twice a month and that's it. Nonetheless, I end up with ~91Kg for my 1,76m height.
Right after the "You're obese!" statement, both me and my girlfriend looked at her with the most stupified faces ever. I'm probably the most critical person about my own body in the world, but I most certainly do not look like someone I would think of when thinking of the word "obese". People laugh every time I tell "obese story" in person.
But she continued nonetheless, and the rest of the consultation was even worse. After hearing our eating habits, the woman told me that as a long-term solution, I could only do "one screw-up a week". I asked if that meant one "screw-up meal" to which she replied "No. One screw-up."
This means, there was this one meal every week where I could choose either I could have some fries or a larger beef or cake for dessert (she actually described things this way).
From that point on, I just stopped paying any attention to what the woman was saying. Or anything any nutritionist ever said, to be honest.
I started by getting an "obese" stamp at the start for measuring weight and height and after that I was immediately treated to a diet that would be directed to someone we see in "The Biggest Looser". No regard was ever given to my fat percentage or muscle mass, just height and weight leading to "stop eating you fattie!".
So I guess all the bodybuilders in the world are morbidly obese. Because they certainly have a higher BMI than I do.
So I say screw nutritionism and nutritionists. I feel fine. I feel healthy. Despite always wanting to be smaller and defined, I like what I see in the mirror. I give all I've got when I'm in the gym, sweat a lot, feel great afterwards.
But I do enjoy eating a lot once in a while. I love good food, always will. If nutritionists are right after all and I should be making one screw-up a week, then maybe I will die young for being obese. Fuck it, at least I lived happily.
Regarding the "exercise has no effect on being obese", I can't really comment on the obese factor because I think its own definition (BMI) is stupid.
What I do know is that, at least on me, exercising has a lot of influence on being fat or not.
A couple of years ago when I had surgery to my foot and couldn't exercise for ~3 months, I got really fat even though my eating habits didn't change much and my weight wasn't that much different from what I have now. Shirts felt tight in the abdomen, pants wouldn't fit in the waist. Going back to the gym solved that in a couple of months.
No matter what pretty studies have been made (now I'm referring to the OP), I can't help but stand by the notion that burning fat through exercise helps people to stop being fat. I couldn't care less to what that means to BMI or obesity, for the above reasons.