Yes, definitely gained over the past 10 years of taking lamotragine and my appetite fluctuates a lot between rapid hunger and absolutely no hunger whatsoever for a few days.
I don't have chronic fatigue but I have horrible insomnia so the exhaustion during daytime effects work productivity. Not a fan of working out myself, nor do I have the time or energy. Oddly swapping out coffee for straight water and that has helped a lot with energy levels. Something to do with oxygenating blood. Electrolyte water, non of that PH crap.
Not sure if it will work for everyone, but the best advice possible is to keep track of side effects in a journal with dates and report back to prescribing Dr.