This is totally random but somewhat relevant. Have you noticed Beyonce's legs lately? I saw her on SNL a few weeks back and her thighs were half the size they used to be. She has always had larger upper thighs and recently they were super tiny. I always assumed that she just had a lot of muscle. I wonder what she did to reduce the bulk in her legs?
Probably started running.
Few random comments from your post and I think Val's.
1. You have to consider how many people choose a particular sport/activity b/c that is what they are most genetically inclined to do. Most marathoners are built for long distance running. Their muscles are more favorably 'built' for endurance. Their bodies don't store fat as easily as others.
I'm not suggesting someone coming from a heavy set background can't excel in marathoning. I'm suggesting in most any sport, the majority of athletes in said sport are going to be genetically inclined.
That's why you don't see many sprinters who are also endurance runners and vice versa. The preponderance of genetics they have favor a specific type of activity.
I bring this up for the simple reason of saying if you consider most marathoners as lean or having the ideal build, I do believe genetics are a huge factor in this observation.
2. We know that endurance running is not conducive for muscle maintenance. That's a fact. We also know to be lean, we need a combination of fat loss and muscle gain.
3. We have to be careful what we're saying here; we're getting close to talking about spot reduction. Running. It is a form of resistance training. Very light resistance training, relatively speaking, but it is resistance training. That said, for someone who hasn't been resistance training, it most likely can and will lead some favorable muscle adaptations. Definitely increased endurance (oxidative) qualities. But quite possibly some hypertrophy of leg musculature since they aren't used to the 'resistance training' component of running. Hypertrophy while losing fat goes a long, long way (even in small amounts) to helping lean out particular body parts, i.e, legs.
So running possibly could lead to some favorable body composition changes like in Melissa's case. She was dieting and running. Started running a lot within the last year. So what do we have? A caloric deficit so fat is going to be lost. We also have overloading resistance on her leg muscles which can and most likely did lead to some hypertrophy. These things in combination are what I would bet my house on led to the changes she highlighted.
But running in itself isn't magic for leg fat. In fact, if I were going to train specifically for leanness, running would be low on the totem pole.
4. Melissa's leg fat most likely isn't as stubborn as Dee's. She has a more balanced fat distribution. Dee allots the majority of her fat in her lower half. If it were my client (being Dee), I most certainly would be implementing something like Lyle's Stubborn Body Fat Solution and replace a lot of the marathon running. Comparing Mel and Dee is comparing apples to oranges.
5. You don't get to pick and choose what sort of muscle changes you see. This is in response to something Melissa said about her muscle changes being lean and not bulky. It might appear that way. However, a muscle either grows or it doesn't. Different attributes of the muscle can 'grow' (see sarcoplasmic vs. myofibrillar hypertrophy) but the fact remains, the muscle will grow or not. It doesn't grow lean vs. grow bulky. In women, especially who are dieting and running shit tons, getting bulky is fucking impossible. That said, looking back over #3, it's easy to see that Melissa experienced nice fat loss in her legs while possibly growing her legs muscles a bit giving them the leaner appearance.
I think I had like 3 more points to make when I was reading through everything but I forget them because my brain is small and retarded.