I have personally seen with my clients that calorie counting is not an effective strategy for weight management. While it is great to keep in mind the calorie count of your favorite foods in relation to their portion size, it is unhealthy to obsess over the math (That's my job!). I have found that the most effective way to educate clients on serving sizes and the issue of overeating is if we focus on nutrient density. Nutrient density of food is the total amount of nutrients, vitamins, and minerals to calories ratio. Fruits and vegetables have a high nutrient density, and sugar has a very low nutrient density.
My favorite examples I use when introducing this concept to clients, are foods like carrots or yogurt. Now carrots are packed with fiber and vitamin A and low calorie. I would never tell a client to count the calories of the carrots they consume in a day. That gives the message that I want carrots to be limited. Eat all the carrots you want and you will never increase your body fat percentage.
Brand name yogurt is rather low in nutrients, and while it has some calcium, it often has added sugars and preservatives and can potentially contain hormones too. This is a food that I do want clients to think about before consuming. By limiting processed foods or at least reducing the portion sizes of these foods, and replacing them with whole foods, my clients gain the education they need to reduce their body weight.
Counting calories can be a useful tool, but obsessing over the numbers is often times too stressful. I always recommend picking nutrient dense foods over strict calorie counting.
Smith-Ryan AE, Antonia J. (2013) Sports Nutrition & Performance Enhancing Supplements (2013) Linus Learning.