I'm confused why it's a win for obese people to not lose fat but gain fat free mass? They gained water and whatever else, not muscle.
Keep in mind the following. GH is not going to cause muscle growth in people who don't train, especially over such a short study period. Now, GH has been shown to cause growth over an extended period of time without training, but not after a few weeks like this study.
Furthermore, just because the people in this study didn't lose any fat, it does not mean MK doesn't cause fat loss. For one, these people were not on a diet...and we all know what MK does to the appetite, so I would be willing to put money on the fact that most of these people actually started eating MORE, which should have resulted in fat GAIN, but none of them gained fat!
Two, there are even studies using actual GH where no fat was lost, when the study was over such a short duration, such as this.
Three, MK was shown to increase energy expenditure...and that alone will cause fat loss over time. The people in this study had increased levels of energy expenditure (increased metabolism).
The bottom line is that GH has a positive effect on fat levels...and MK significantly increases GH levels. These people didn't train, didn't control their diet, and likely ate MORE than usually because of MK's significant appetite stimulating effects...yet they still gained no fat. Plus, we all know that MK has been shown to increase lean mass, significantly, during longer study periods (and especially in those who train).