If you are using B12 injections as part of a weight loss program, you might notice the benefits of a more regular metabolism and higher energy levels
PMID 9786866
The benefit of this is that this higher dose can be injected in one shot and the benefits of B12 supplementation may be felt sooner
A GP or relevant specialist can help assess individual risk, identify potential contraindications, and provide guidance grounded in evidence-based medicine
Wang G, Zhao L, jiang Q, Sun Y, Zhao D, Sun M, et al
Though you shouldnt expect an improvement for hooded eyes where the excess skin in the eyelid is the primary cause (because that tends to be due to loss of volume in the eyelid and loss of elasticity in that eyelid skin, which cannot be influenced too much by an area so far away as the temples)