I experimented with it during my cutting phase last year.
I was doing keto diet for a while. I did a 2 week run with 250mg dnp, 3iu hgh, 3iu fast acting insulin. All upon waking, on empty stomach, doing 40min fasted cardio on my crosstrainer.
I can handle 3iu fast acting insulin. On empty stomach, but not much more then that...
But did it help me burn more fat? Hard to tell.
While on keto. The whole idea is not having insulin present, and Id say it probaly didnt help at all. Rather hinders the fatburn during its active time.
Since insulin stores energy. Rather then burns it.
I have to mention though, I was pissing more ketones then ever during that run. Once I had my egg and bacon breakfest
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The theory behind it is that it pushes down glucose levels and the body need energy while your training, forcing it to break down fat for energy, since glucose is not available at all.
Try it, at least it will give you a great pump during workouts, even on keto