Eating healthy and getting fatter?

In my ten years of personal training hundreds of clients, I have had the following discussion many, many times:
PT: Alright, I understand your number one goal here is to lose weight, primarily body fat, correct?
Client: Yes
PT: Ok, the first thing to look at no matter your goal, but especially this one, is your diet.
Client: Oh, trust ME, I eat healthy. 
PT: Ok, lets hear your average days diet, from breakfast to bedtime.
At this point the client will give a rundown of an average day and, yes, it is full of very healthy food choices.
And then I explain that they can expect to gain steadily unless their activity level raises dramatically.
You see, it  is possible to eat yourself obese with very healthy foods.
This is because, at the end of the day, it is not WHAT you eat, but HOW MUCH you eat.  If you eat more calories than your body uses during the day, you will gain weight.  If you eat less, you will lose.
It is popular lately for people to claim they do not count calories, because what matters most is just eating healthy.
True.  But not for weight loss.
When someone is eating something they KNOW is bad, they tend to be very aware of the caloric value of that food.  That’s a good thing.  Even though it’s not conducive to weight loss, at LEAST they are aware of exactly what they are doing.
That is usually not the case for those under the illusion that simply eating healthy will drop pounds on the scale.  Most tend to disregard quantity and nutrition information when eating bowls of fruit, nuts, oils and other “healthy” food items.  After all, its health food!
Salads are the perfect example.   A salad like the California Chicken Salad at O’Charley’s sounds great on paper.  Romaine lettuce, walnuts, cranberries, mandarin oranges, grilled chicken and balsamic vinegrette dressing sounds pretty healthy.  It’s also 800+ calories.  Thats almost half a days calories for the average “diet.”  Those calories can add up fast.
When losing weight, you MUST BE aware of total caloric intake.  You can certainly eat healthy, but the calories for the day must put you at a deficit or you will not lose weight. Period.
Matt Pirtle, MA, CSCS