At your level of training a lifting belt really isn't needed, and, in fact, will be decremental to your core stabilization development. Your trainer really needs to study this further.
Under very heavy load, weight belts, and knee wraps, wrist wraps, make some sense, but, sounds like you're very neophyte, and a lifting belt would be contraindicated.
Those of you who've read my posts know this: you never coddle the weakest part. You work it. You improve it. You make it stronger. A lifting belt is contraindicated in a neophyte resistance trainer.
You need to keep from developing any imbalance, which any support device will encourage.
Again, just a case of common sense 101.