Hunger in 20/4 after 3 weeks or so

Hi everyone, I'm on a 20/4 routine consisting of a snack (almonds, ham, cheese) and a meal which was mostly keto and always low-to-no carbs since the beginning. This weekend I introduced some carbs with few steam cooked patatoes (Friday) and rice (Sat.) with my meal. I also run 10km 2 times a week. Since then I get to have hunger waves during the day which I didn't have before. I also noticed a gain of weight of almost 1kg during the weekend. Do you think that these hunger waves are linked to the carbs ? Would it be related to 3 weeks of 20/4 and my body getting tired of it ? The running sessions ? What would be the scientific rationale for that because at each meal I feel fulfilled. Or maybe it's just a phase and I'll move on soon. Thank you for your hints 🙏