People, please keep in mind that MK-677 is a ghrelin agonist...and therefore, it can (and will) negatively affect fat loss via the typical Ghrelin pathways. However, this negative effect is typically offset by the substantial increase in GH that it produces. This is why most people report a neutral effect on body fat levels when using MK.
On the other hand, if fat loss is the goal and someone is already using exo. GH for that purpose, then the inclusion of MK may have a mild detrimental effect on fat loss, as the "offset effect" mentioned earlier is no longer relevant due to the inclusion of exo. GH.
In conclusion, MK-677 has a neutral effect on fat loss in people who aren't using exo. GH, but a mildly detrimental effect on fat loss in people who are.
Now, when it comes to the off-season, it is a completely different animal and has benefitted many people...immensely...for packing on muscle mass. This is especially true for those who need to really pound down the calories and/or have a fast metabolism. Basically, anyone who struggles to take in an optimal amount of calories, day in and day out, is likely to derive great benefit from MK-677. Of course, it's ability to raise GH and IGF-1 levels helps build muscle tissue as well, while its benefits on connective tissue (and the joints via intrajoint water retention) have helped many people continue pushing heavy weights pain/injury free.
In truth, I believe that MK is--potentially--one of the very BEST muscle building aides available. This goes for all ghrelin agonists (which includes the other GHRPs), as their ability to increase appetite can make all the difference for someone who struggles to take in an optimal amount of calories for growth. As we all know, if you don't eat enough to grow, you won't. Nothing will kill your progress faster than insufficient eating...and the bigger someone gets, the more calories they need. Many people never make it past a local level of muscle size (despite using a ton of drugs) for this very reason. They hit a certain size and never move beyond it because they fail to adjust their diet accordingly. Rarely is drug dosage the problem. Most often, it is diet related. MANY people never come anywhere close to what they could be precisely because of this.
Any product that can help someone overcome this issues is of a great worth to them. The guys who have slow metabolisms...or those who never struggled with eating enough caloris to maximize growth, will NEVER understand how brutally challenging it can be to force-feed day in and day out, all year round. Many competitors in this situation actually look forward to their contest prep diets simply because they won't have to constantly stuff themselves anymore.
Also, as I said previously, we can't discount the fact that it also elevates GH and IGF-1 levels the equivalent of roughly 3-3.5iu of exo. GH daily. This DOES matter. In the case of Somatozine, while GH and IGF-1 elevations are slightly greater than what we see with regular MK products, Somatozine also has many other beneficial effects which help the body to more effectively use the GH and IGF-1 it produces. For example, Somatozine not only increases the active life of IGF-1 beyond that of MK alone, but it also helps the body more effectively utilize that IGF-1 for muscle growth by increasing levels of IGFBP-3 (an important IGF-1 transporter protein) to a greater degree than straight MK-677. These are just two of about a dozen things that Somatozine does better than regular MK-677, but the point is that MK-677 has numerous potential benefits for the bodybuilder trying to pack on muscle mass.