A study by Ebbeling, Ludwig et al was published in JAMA today, but began making headlines yesterday.  I want to give you a one or two (i.e 4) paragraph summary and a take home message.  I do this because I found the headlines and the stories behind them to be misleading and at times inaccurate.  I emailed one reporter directly in this regard.
    A controlled study of 21 people who were overweight or obese (average BMI was 37), found that the composition of diet patterns had an affect on resting and total energy expenditure.  REE/TEE = calories burned.  This diet comparison occurred after the participants had succeeded in losing 10% of their beginning weights.  During weight loss and weight maintenance, the people remained in a hospital setting and ate the food provided to them.  Each person consumed each type of study diet. I am not sure how long they were on them, but they were given them in random orders.  The 3 diets had different amounts of carbs and fat, but the same amount of protein.  The important factor seems to be the glycemic load.
    The study suggests and adds evidence to the research that calories are not equal.  When compared side by side there was no evidence to support a difference in REE/TEE between the three diets. However, each diet pattern had a different glycemic load, and the researchers did provide evidence that as the load went down, the REE/TEE went up.  We want our expenditure to be as high as possible after weight loss in order to maintain it.
    Take home message:  Choosing foods with  a lower glycemic load (GL) seems like a good idea.  Fat intake can lower the glycemic load of a total meal, but be careful there and choose healthy fats more often than saturated ones.  ALSO- sometimes a foods glycemic index and glycemic load contradict each other.  It is the GL that you want to focus on if that is the case - choose lower.  A low GL food is 10 or less and you can see more about that here. Both the GI and GL refer to carbohydrates.  
    In this study, whatever diet pattern the subject was on (1,2 or 3), the overall calorie intake was the same.  There fore, calorie type is important but overall calories still count.