When I read forums or comments about people wanting to lose weight, the most common complaint I hear is something to the effect of, 'I work out everyday and eat healthy food, and I lost a little weight, but I can't lose anymore.' The fact that people believe this type of behavior is enough to lose weight is a reflection on how the media continues to fail people in regards to informing them on what makes us fat.
If you believe all of what you hear about fat people, you think that they all got that way stuffing their maws with fast food and junk food. You also think they are lazy and watching T.V. or playing video games all day. Here's the thing; you can get fat from any type of food, even healthy food. You can be fat if you are very active. Losing weight is far less about what you eat and do than about how much you eat. Period. You can be thin eating McDonald's everyday and sitting on your duff, and you can be fat eating vegetables, high fiber foods, and lean meat and running 5 miles a day.
The perception that all you have to do is be "good" also shows just how poorly educated people are about calories in general. That is, they think there is a relationship between the nutritive value of something and the caloric density. Oatmeal is good for you. Milk is good for you. If you make yourself a bowl of oatmeal with a half cup of dry oatmeal and a half cup of whole milk, the calories are going to come out to 282. If you happen to add some fruit to it, say just half a banana, you're going to boost that up to around 340 calories. If you add even a tablespoon of brown sugar (or honey) to make it more palatable, you're up to 390 calories. Congratulations! Your healthy breakfast now has almost the same number of calories as two Krispy Kreme original glazed donuts (400 calories). Even without the banana, and with skim milk, your oatmeal is the same number of calories as one donut, and your body is going to treat those calories the same when it comes to fat loss or storage. If you eat your healthy oatmeal and your skinny compatriot has one donut and a black coffee, she's going to be eating less than you.
Of course, you will probably feel sated longer with the oatmeal (probably, though frankly it doesn't work that way for me), and it is undeniably healthier for you as your body can take the fiber and other nutrients and use them to help with vital processes like healing, muscle-building, etc. However, my point isn't that the donuts are better for you or equal, but rather that in terms of weight loss, being "good" isn't going to help you lose weight unless you are very aware of the total number of calories you're consuming in healthy foods.
As long as the stereotype of fat people becoming fat is linked to excessive consumption of empty calories and sloth, people who want to lose weight are going to keep thinking that eating good food and exercising are all it takes to lose weight. It takes so much more than that, and it is cumbersome and fussy. You don't have to count calories, but you do have to reduce portions and be aware of how much you're eating with at least some vague idea of how many calories are involved rather than only concern yourself with what types of food you are eating. To me, this is yet another problem that results from people oversimplifying things. They want easy answers and easy advice, and having to weigh and measure your food, and count calories isn't easy.