it's a mix of both. I have been doing intermittent fasting for 4-5 years now, i used to be able to lose my weight and maintain it at low -er level. my metabolism has perhaps slowed down and IF is no longer working on its own and I could no longer eat whatever the hell i bloody want. Perhaps try swimming, it's like the only sports that doesn't feel like Essesise imo.

Also are you a woman? I'm asking because women can gain weight due to hormonal fluctuations so it's natural? And if by fatter you mean appearance-wise, could be due to salt retention and what not - try cutting down sodium intake.