Open Question: am i running long enough to lose weight?

i dont go by miles because my treadmill is just so inaccurate with miles so i go by time i jog/walk 20 minutes about 4.0 fastest. i guess thats 4mph yeah. so am i running long enough to actually lose weight or should i run 40 minutes? Also i need help with protein shake i usually take one after i lift weights and jog but i jog on different days so is it okay if i take protein shake after i jog