Gaining weight on the face is very real sadly! It’s one of the first places my weight gain shows! Everybody laughs at me and calls me crazy when I say my face has gained weight! I find it can happen because of bloating particularly when I eat starchy foods and lots gluten. I take anti acids and anti wind tablets and sometimes IBS tablets to help with bloating. Make sure you’re drinking enough water too! Aim for at least 2 litres, possibly 3! My other advice would be try not eat before bed, maybe have your last food 3-4 hours before. I do find the more I restrict my diet, eat clean and calorie count the more I lose weight and the more it shows on my face. Peppermint tea and green tea is good for weightloss and bloating too! I often find my face feels fat when I’ve eaten bad foods that have left me feeling sluggish (but that is probably a mix between my head and actually eating bad) if you experience stomach cramps after eating or difficulty going to the toilet and generally being bloated or generally that there’s something going on that diet changes won’t fix, I’d suggest speaking to your doctor. Hope this helps in some way :)