Pre-workout most likely will break your fast, but if you read the nutrition facts carefully, you can possibly find a calorie free one which will not break your fast.
How many calories break a fast?
Maybe you’re one of them. I have a glass of water. Well you don’t have to dump your morning routine if you want to give fasting a try. The general rule of thumb is that if you stay under 50 calories, then you’ll remain in the fasted state.
Do BCAAs spike insulin levels?
Despite the positive effects of BCAAs on metabolism, the strong association of BCAA levels with insulin resistance and metabolic syndrome suggests that increased levels of BCAAs may cause insulin resistance and T2DM, although this remains a speculation for now.