lost strength after weight loss

ambroselehner thought this was worth mentioning said


I started bulking few months ago and I was 5’7" 150 pounds. I figured out that my bulk was more fat than a lean mass so last month I started cardio. I figured out that my legs started building up but after going from 150 pounds to 140 pounds I lost my upper body strength. I am not able to bench press as high i used to. I had to reduce bench press weight by 15 pounds. I feel that i have got pretty weak. I am doing lean bulking now and trying to gain slow but I am so disappointed by my loss of strength. Has this happened with you? what should I do to gain more strength without doing dirty bulk? thanks