MK 677, also known as Ibutamoren, has gained popularity among bodybuilders and athletes due to its effect on growth hormone levels and IGF-1.
In this guide, we will provide answers to many common questions about Ibutamoren.
What is MK 677?
MK 677 is a Growth-Hormone-Releasing-Hormone, or a Growth Hormone secretagogue. As the name implies, this means it causes a release in Growth Hormone.
It does this by mimicking the hormone ghrelin in the brain. You may have heard about this hormone before as it is a key chemical in hunger.
Recently, there have been a few of these products to surface on the market, including Growth-Hormone-Releasing-Peptide-6 and Hexarelin.
One of the benefits of MK-677, compared to other growth hormone releasing substances, is that it doesn’t affect cortisol levels.
This is a huge advantage, because cortisol increases fat storage, anxiety and blood pressure. Ibutamoren does not have any of these unwanted effects.

What are the benefits of MK-677?
The benefits of MK-677 include muscle-building, a reduction in muscle wasting, better bone density, improved sleep, and anti-aging properties. It may also have nootropic effects and it can be beneficial in treating growth hormone deficiencies. Read on for a more in-depth look at these benefits.
Helps build muscle
Ibutamoren is frequently used as an anabolic substance to increase lean body mass. It is orally active and can be taken once a day. MK-677 stimulates Growth Hormone and IGF-1 which each factor in significantly maintaining lean body mass.
Growth hormone stimulates muscle size and strength, and Ibutamoren has proven to effectively stimulate the secretion of GH.
Reduces muscle wasting
MK-677 has shown in recent studies to alleviate muscle wasting, which can be caused by a decline in protein within an individual’s diet. In one study a group of healthy young adults were tested to determine if MK-677 could reverse protein catabolism and the results proved to be quite positive. As a result, MK-677 is theorized to be possibly being an effective treatment for individuals who suffer from catabolic conditions.
Improves sleep
By increasing Growth Hormone, Ibutamoren can help improve sleep quality. We know from studies that it improves sleep quality and the duration of REM (Rapid Eye Movement) sleep duration.
Apart from scientific studies, there have been many reports of subjective improvements in sleep quality.
This is beneficial for multiple reasons, one of which is better recovery after working out.

MK 677 side effects
Now that we have covered the benefits of this compound, it is time to discuss the MK 677 side effects. Because Ibutamoren doesn’t have any androgenic properties, there is no suppression of testosterone associated with it.
However, this does not mean that MK677 side effects are non-existing. Possible side effects include:
- Water retention
- Increased hunger
- Reduced insulin sensitivity (rare)
- Headaches (rare)
Water retention
This is a pretty common MK 677 side effect. Most people do not experience this at all, and those that do, report it mainly during the first week of their cycle. We can easily prevent or at least reduce this side effect by simply drinking more water.
So if you notice water retention in your legs/feet or hands, make sure to drink more water. You will likely see that it will go away in a couple of days. If it doesn’t, there is no reason for concern as this side effect is mostly harmless and will be gone after your cycle anyway.
Increased hunger
Increased hunger is the most famous “side effect” of MK 677. For you, it might be a benefit, for some other people it might be a side effect.
If you want to avoid an increase in hunger, take the dosage before going to sleep. If you want to have increased hunger, take the dosage in the morning. This effect wears off in a few weeks into the cycle anyway.
You should notice an increase in hunger in the first week or two. But some people don’t even experience this, we are all different so not everyone experiences this but most people do.
Reduced insulin sensitivity
Some people report that their insulin sensitivity got reduced on their MK 677 cycle. Very few people report this, but still, some do. This could be a problem for type 2 diabetes patients.
The good news is that clinical trials have researched this by measuring blood glucose levels. It turns out that MK 677 doesn’t actually change blood glucose levels at all, proving that Ibutamoren won’t reduce insulin sensitivity.
It is possible that the few that reported this, actually had a bunk product. This goes to show the importance of purchasing from a reliable source.
When to take MK 677?
Ibutamoren has a half-life of 24 according to recent studies. This means that we have to take it every 24 hours to get the most benefit.
You should take Ibutamoren in a single dose each day at the same time. With regards to the question “when to take MK677 during the day“, you have several options. Some people take their dosage in the morning, others prefer the evening. When you take your dose in the morning, you can benefit from the fact that it will increase hunger, which means that you can gain weight faster. If you take it in the evening, you can prevent being hungry and instead get amazing sleep. As we all now, it is during sleep that recovery takes place.
The best time to take MK677, depends on which of these effects you prefer.
How long to take MK 677?
The minimum recommended cycle length for MK 677 is 8 weeks, but 16 to 20 weeks is actually better. While the increase in growth hormone levels is pretty much instant, IGF-1 levels take a while to build up. This basically means that the longer you take Ibutamoren, the more effective it is.
During clinical trials the participants where given 25 mg daily for a period of 2 years.
How long does it take to work?
You will notice a strong increase in appetite already during the first week. Some people would describe it as extremely hungry. During the second week, you should notice the improved sleep quality associated with Ibutamoren. The anabolic effects of MK-677 will take longer to kick in. It takes at least 4 weeks to notice any difference in muscle mass or strength and these benefits will become more apparent when taken for an extended amount of time.
What is the optimal dosage of MK-677?
Ibutamoren is used in dosages between 10 and 50 mg per day. The optimal dose of MK-677 is roughly 25 mg per day. Anything above this dose will likely produce more side effects, while having limited additional benefits.
How does Ibutamoren work?
Is MK 677 a SARM?
Some people mistake MK677 for a SARM (Selective Androgen Receptor Modulator). In reality, it’s actually not a SARM, but a growth hormone secretagogue. Unlike SARMs, which target the androgen receptors much in the same way as anabolic steroids, Ibutamoren influences the levels of human growth hormone and IGF-1.
Does MK 677 cause testosterone suppression?
Since Ibutamoren doesn’t affect the androgen receptors, it does not lead to a decrease in natural testosterone production. Since it is not suppressive, there is no need for any type of PCT.
Is MK 677 legal?
The legal status of this compound is the same as other SARMs. So yes, MK 677 is legal to buy and use in every country around the world. There is one exception, Australia, where you will need a doctor’s prescription for it because it’s a Schedule 4 prescription only compound.
Ibutamoren has not been approved for human consumption, and is currently still a investigational new drug. This means it can be legally sold as a research chemical.
For more information on the legal status of SARMs, read our blog post: Are SARMs legal in Europe?
Can I stack MK-677?
Ibutamoren can be stacked with SARMs or other compounds, depending on your goal. It can be used for cutting purposes, in combination with Cardarine, or for bulking in a stack with LGD-4033 or RAD-140.
For more information about stacking SARMs, read our blog post: Stacking SARMs: The ultimate guide.