I've been on Biktarvy for a couple of years and have experienced weight gain. A friend told me to talk to my doctor and make the switch to Dovato as it's a much better HIV drug and has less issues with weight gain.
I switched to Dovato about 5 weeks ago. (Not from Biktarvy but Descovy and Raltegravir). I haven’t experienced any side effects, and my first blood test after 4 weeks was “satisfactory”. My weight has gone down very slightly. Hope you find a treatment that works for you.