As I stated- I am on almost 75 planes a year. Many of those trips I do not bring a checked bag so I am limited on space in my carry on. My clothes usually make up 1/2 my bag, shoes 1/4 and supplements the remaining 1/4.
On Domestic flights- there are NO limits on powders. Literally none. You could bring 45lbs of powder through TSA if you were so inclined. I have NEVER had a powder taken from me from my carry on on either a domestic or international fight. There are very rare cases that a tub of product will trigger an alarm in which TSA will swab in and return it to you. This happens to me maybe 5% of the time I fly. There are very, very few instances in which they will take a product from you and that only is when the swab detects something on the outside of the tub (it could be a multitude of things ranging from soap, perfume, gun powder, etc). If you are worried about TSA, simply check your bag and put your supplements in there. For international fights- it is recommended you contact the airline directly to discuss powder restrictions for your specific itinerary.
I truly hope these tips helped with traveling with supplements!