Frankly, for me, there is no 'perfect diet' to ever be found, because we are not
supposed to diet. I've tried to put it all back into perspective while reading that book, and really, WE overweight and obese people, we who have a tendency to easily put on weight, are actually the survivors of the human species, the ones who are supposed to to survive to the long periods of starvation, and to perpetuate the human race. It's as simple as that. 500 years ago, we would have been the ones to go through a whole winter of famine, and the 'real skinnies' would have died. Seriously, boys and gals, we rock.
The current problem IMHO is that society and means of living have evolved past a point where 'too much' has become the norm, and our bodies just haven't caught up to all the easily-available sugar and junk food (okay, I know many of us also have problems with emotional eating and the likes, but we wouldn't have been able to give in to that at the time anyway--can't binge on cupcakes in front of the TV out of boredom when you have to plow your field all day long and know all there is to eat tonight is a few roots

). We can't erase 3 million years of evolution in two centuries, of course. So, every kind of ideal weight/ideal body we want to attain is just a mere illusion. BMI charts are just numbers. There is a solid difference between morbidly obese (being really too heavy for your body to go on carrying the weight without problems) and 'just a little plump', but this difference seems to have blurred with time. Now all that appears to be left is that either you're fat or you're perfect, and perfection isn't and has never been attainable, no matter how much Botox we try to put in it.
So, yes, to me, people in general tend to struggle because expectations have become unrealistic. (Again, difference between health being at risk and vanity pouds.) We're surrounded by those, everywhere, all the time... it's kind of hard to not let it influence us, for the better or the worse. I quite agree that in a way, the part played by society does play an important part in all of that; peer pressure has always been a drag. Tabloids scream murder because "so and so is OH MY GOD 110 lbs she's FAT!": of course we're going to believe it, after a while of hearing that stuff... (Especially those of us who've been overweight since childhood and don't even have any idea of what weight to aim for, i'd say.)