vitamin b12 deficiency
"I am 50  
Initially I tried it to fight depression and low energy. Hoped it would help me trim off 10 lbs without the need for a diet. At first it helped, but after a few months I started gaining weight and developed muscle fatigue. I literally weakened by about 20% These injections began having a negative effect on me for everything I hoped they would help. I am not taking another one."