These are super comfy and I would say are sweat proof, but not leak proof. If you can't hold it in for a while, make sure you go to the bathroom a lot. I tried these because I sweat and or leak a lot, and I wear a daily pad everyday just to make sure my underwear stays dry. The inside thighs of these underwear did stay dry, but I need to make sure I get to the bathroom a little more to prevent leakage. Also, the size chart seemed inaccurate to me. I measured my body to a t and ordered the exact size the chart showed and the underwear I received was 2 sizes too big for me. What ended up working best was using the size chart of what I currently wear and compare it to the Knotty size chart. Now these fit perfectly and are oh so comfortable! I like the length of the boxers too because I don't get thigh rub from them. Also, the customer service was amazing! I had to contact them twice and both times I received a response within an hour.