I started taking gabapentin in 2016 after stabbing, fiery nerve pain post an L5/S1 fusion. It allowed me to get off of opioids which for me had worse side effects.
Side effects for me on Gabapentin did not include any weight gain. Mine were more typical such as drowsiness, unsteadiness on feet when first getting up and foggy thinking. These dissipated as my body became more used to the 2100mg/day dose - split into 3 times a day. For me the side effects were worth the relief given.
I recently had a spinal cord stimulator implanted so have not needed the gabapentin. During the years I was on it, my greatest relief was at night when it helped me sleep. I did have to plan ahead on timing of taking it so i wasn’t driving immediately after dosing. But I also talked to plenty of others who attributed horrible nightmares to the drug or extreme sleepiness that couldn’t tolerate it. Always good to remember we are all different so what might work for one doesn’t for another.