It has some steps and without pictures you cant do it. I didnt find it with quick search...
Step 1 /effect @a 22 99999 255
Step 2 /effect @a 21 99999 255
Step 3 /effect @a 10 99999 255
Now you got a lot of harts that regen realy fast but over time they glitch back to 1 bar...
sorry i found out it is a duplicate