I'm thinking it's not a matter of "normal" it's just that the food easily obtainable these days is not satisfying being highly processed and is full of bad carbs, so we tend to eat more of it, and since women as a rule more easily gain weight and are less able to lose the weight once gained, women start trying to figure out what is going on and how to both eat to be healthy, to enjoy and not instantly gain weight.
I'm on a modified Atkins diet. It teaches you what foods have more fiber and less sugar than others. You think, hey this is a snap to go shopping for food now, then you start reading the labels off easy to prepare foods and realize the majority of foods on the shelves and the freezer section are full of sugars and highly processed carbs. There is almost nothing I can eat off the shelves that isn't full of sugar and bad carbs. I almost literally have to prepare all my foods from fresh produce and meats.
And for someone who doesn't like to cook, this is a pain in the ass. So yes, I have to think a lot more about food and what I am going to eat than is 'normal' because it is no longer a "no brainer" just to grab something to eat off the shelves or freezer section or in a restaurant.
And some of it I do attribute to social pressure for women to be thin and some of it depends on the women involved. Some women have addictive personalities and others are very "A-type" so why wouldn't some women also be overly obsessed with dieting and weight gain and exercise?
A friend of mine is "A type" and is very obese, she works out regularly, but doesn't watch what she eats and tortures herself by getting on a scale twice a week.
I am not "A type", I don't work out as much as I should, but I am careful about what I eat and still manage to lose weight, but haven't gotten on a scale in 3 years.
SELF magazine didn't say where the women in their study/poll came from.