You can create an insulin spike with leucine, no carbs necessary if that meets your goals
There are studies that show that post workout carbs and protein increase performance, not necessarily size. And protein doesn't boost insulin...insulin is a hormone released to reduce blood sugar (blood glucose/carbs), not to regulate protein.
Insulin Crushes Cortisol, Increases Nitric Oxide, and causes water storage within the Muscle via Glycogen storage, and im sure plenty more I cant bring up off the top of my head
There is a reason Natural Bodybuilders inject Insulin
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I think there are a lot of myths regarding insulin. It takes super-physiological levels of insulin to get the anabolic effect it has on the body.
BioLayne Video Log 18 - Carbohydrate Metabolism: What Intake is Right for You? - YouTube
From my experience spiking insulin post workout just makes me bloated and fat... Take your whey protein and then 1h after eat a good meal with carbs and protein like rice with chicken