I see your approach. You're using epicatechin as an indirect aggressor to suppress myostatin through the oral route rather than myostatin or myostatin suppressor agents via injections. What got me interested is the 300mg rather than 2g dose. If you calculate the 300mg from pure 98% cacao bean, bitter as crap if you ask me, the total is around 5% suppression at max even with 5g of creatine monohydrate to boost the blood activities to deliver the epicatechin more effectively.
Between 300g and 600g of epicatechin, you're talking at max around 5% to 20% at max. It could be something else in your diet that you didn't take into account for the 300g of epicatechin to suppress 20% to 30% of the myostatin.
This article is a 2018 metabolic cycling of epicatechin for human trials, with hints on the myostatin suppressor.
This one is focused on the low vs high dose loading in humans, roughly around 87mg/kg. Let's say we average ourselves around 90kg (200lbs), that's around 7.8g of epicatechin for the period of daily and 3 months to have detrimental effects, with roughly 100% myostatin suppression. Breaking it down, 300g is around 4% at best, 5% to give/take of marginal error. 600mg is definitely around 10%. But if this works for you, definitely more power to you brother. Something we can really sink our teeth into or turn our heads because of the bitterness.
I drink plenty of green tea (full powder form) during work to keep myself cool/warm and hydrated all day besides coffee. Something to also think about besides dark cacao. Plenty of epicatechin-rich foods as well.