While in the bulking phase, you need to lift heavy to add on muscle mass which increases your chances of muscle fatigue
26 Adverse Effects
That principle applies to everything, including GLP-1 medications for weight management
According to MHRA product information for hydroxocobalamin (the standard injectable form used in the UK), common side effects include injection site reactions and occasional hypersensitivity reactions, but anxiety is not listed as a recognised adverse effect of B12 supplementation
The bottom line There are lots of positive health benefits from using a GLP-1 to eat less and lose weight, but there are also a few challenges, especially losing bone density and muscle mass
They found a high rate of deficiency based on typical reference ranges and determined that it doesnt require 20 to 30 years of being vegetarian to develop a deficiency, a popular belief among vegetarians (Pawlak, 2013)