Does Fitness or Fullness Determine your Fatness?

A couple of months ago we had a discussion on this blog about the relative importances of diet versus exercise in achieving weight loss. Yesterday in my pile of monthly journals I received my copy of Medicine & Science in Sports and Exercise (MSSE), the official monthly journal of the American College of Sports Medicine.  MSSE is an interesting journal -- it is a combination of clinical research, basic science, and applied studies often involving human participants.  If you are a lay person with any interest in exercise or exercise prescription, this is a very accessible journal in terms of the ability to interpret the content, and some of the articles are freely available.  Including the one that caught my attention this month...
But, I digress.  In this month's MSSE is an article presenting a subset of data from the large, clinical Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) study.  In this component of the study, Eric Ravussin's group looked at the effect of caloric restriction or caloric restriction plus exercise on weight loss and markers of cardiovascular fitness.  In brief, they enrolled 36 sedentary, overweight individuals  and assigned them to one of three groups - a control group (CO) where individuals did not change food intake or fitness,  a calorie restricted (CR) group in which the participants cut their intake by 25%, or a calorie restricted plus exercise (CR+EX) group in which the participants cut their intake by 12.5% and exercised sufficient to create a deficit of an additional 12.5%.  What's important to note for the rest of our discussion is that over the 24 week period,  the CR and CR+EX groups had exactly the same calorie deficits.

Before we talk about the results, I think it is important to point out how challenging this studies are to conduct.  For weeks 7-24 of this study participants went to the study center 5x/week to exercise.  They attended weekly group meetings to ensure compliance and for weeks 1-12 and 22-24 the study center provided the participants with all of their meals.  That is a huge undertaking.