Wow, your keto bread looks very nice! I have tried many different recipes in the past and have never had very good success. Usually it doesn't rise, or it's uncooked in the middle...

As for the keto flu, it is totally avoidable! Just remember to keep up your electrolytes! When you go keto, your body lets go of a lot of water, which is dehydrating and yes it can feel like a hangover. You can plan ahead and counteract this effect by making sure to eat plenty of salty foods.

An easy thing to do is get powdered or cubed bouillon and add to hot water and drink. Salty snacks too like olives, cheese, etc are good. Green stuff like avocados and celery are great sources of electrolytes too. Basically look for foods high in potassium, sodium, calcium, and magnesium.