We're not big fans of counting calories as this system is very flawed. It assumes that everyone processes calories in the same way (which is just not true) and pushes many to seek out low calorie foods. Many of these so called 'health foods' lack vital nutrients and are loaded with artificial sweeteners and chemicals in order to get numbers as low as possible. Pitch a high calorie avocado that is brimming with nutrients against a low fat yogurt and you'll start to see what I mean.
We wrote a very popular blog post on this which can be viewed here, I hope this helps.