I tried it when I was dating a girl who was vegan. She had been a long time vegan and after following her diet for 2 weeks I could not even walk up the stairs to my office due to the energy loss. I managed to walk half a block to the nearest burger shop and ordered the greasiest item on the menu. I instantly felt better.
If you are going vegan for social reasons (animals being abused on factory frankenstien farms) you can just switch to grass fed beef or bison. At least the animals live a good life before they are slaughtered
Plus the meat is very healthy to eat vs the grain fed animals which is not natural at all.