I think that these pro boxers can probably get through even though they are dehydrated in a fight, I think that they have been trained to perform under that circumstances.
For sure, I said "dehydrated boxer" in a good way, it means Lopez can suppress his actual weight until the weigh-in. After the event he will get insta-buff and box like a welterweight boxer. It's a well-known strategy especially for young boxer who can recover pretty fast from dehydration. This ability will diminish when he is getting older, but it will happen long after Loma retired.