In order for a diet – any diet – to work, an organism’s expended energy must be greater than its caloric intake. Put simply, you need to eat fewer calories than you’re burning. However, being in a hypocaloric state has unwanted consequences, which typically include the loss of hard-earned muscle mass.
However, MK-677, an oral compound that has been proven to increase the body’s production of Growth Hormone (GH), can not only help the body hold onto muscle during periods of calorie restriction, but can actually reverse muscle loss (catabolism) under those conditions.
The Merck Company first began developing MK-677 over two decades ago, as a new class of, orally active growth hormone secretagogues. The “MK” – as you may have guessed – stands for Merck (ergo: Merck-677). Secretagogues are substances that cause the body to secrete something, in this case to increase its own natural Growth Hormone release. Here, we find that MK-677 mimics the effects of Growth Hormone Releasing Hormone (GHRH), which in turn causes the body to release GH, and eventually Insulin-like Growth Factor-1. This is beneficial because there’s no catastrophic insult to the Growth Hormone/IGF-1 axis or feedback loop.
A study performed in 1998, calorically restricted eight healthy volunteers (ages 24-39 yr) were calorically restricted for two separate 14-day periods. For the first seven days, they simply had their calories restricted. For the second (the last seven days) of each diet period, they received a daily dose of 25mgs of MK-677, or a placebo. Between these 14-day test periods, they had a 14- to 21-day washout interval, of normal eating, after which the groups switched treatments. In other words, the guys received the MK-677 on the first trial, would now get the placebo, and vice-versa. This type of “double-crossover” design is useful to insure that the results are not only accurate, but repeatable.
Over the first week of caloric restriction, the scientists observed and measured the nitrogen (protein) losses in the subjects. The more lost nitrogen one experiences during dieting, the more protein, and consequently, muscle, is forfeit. Beginning with the second week, when half of the subjects received MK-677, those subjects improved their nitrogen balance for the remaining the seven days of treatment – in contrast, the group that received the placebo continued to lose muscle.
The group receiving MK-677 showed higher GH levels than the placebo group, as well as higher levels of Insulin-like Growth Factor-1. Because both GH and IGF-1 are well known to reduce body fat and build muscle, the long term effects of this type of treatment would be unlikely to end with simply allowing dieters (or anyone in a hypocaloric state) to retain muscle, but would most likely allow them to build more muscle and lose more fat.
The bottom line is that 20mgs per day of MK-677 is especially useful for anyone not eating enough calories, as it will certainly prevent muscle loss, perhaps aid in building more muscle, but will also accelerate fat loss as well.