> I mean I don’t think I’m eating enough calories to be gaining 6 lbs in 2 days, right?
Yes, that would be in the neighborhood of 21,000 additional calories on top of maintenance. While not impossible, pretty infeasible for most folks.
So the water weight spike has to do with how the body stores calories, it’s not just as fat. Your body essentially tucks away sugar water for itself in a few places. Extra salt will also cause the body to hold on to more water than usual.
Menstrual cycles play a huge part in weight fluctuation, women can gain 5lbs throughout the day, water plays a part, sodium makes you retain water more, also digesting food can take up to 3 days so poop still inside you will also make you weigh more. All of those factors will contribute to spiked weight gain in a short amount of time. This is why weighing daily or even weekly is too frequent. I recommend weighing every 2 weeks-month.
So I combine IF with OMAD and keto which have all showed me a lot about my diet. Carbs make you retain water so when switching to keto dropped 8lbs the first week because no Carbs and my bloating went away. I had to actually increase electrolyte intake. After that it’s been a fairly steady progression of 1-3lbs a week. However I have had a few plateau times as well because you know I have cheated on keto, pop chips. But I get myself back on track. I’d recommend at least getting bare minimum protein which seems to be .37g per lean body mass. Max where you get no more benefit from protein besides calories is .8-1g per lean body mass. Fill in rest with whatever unless you’re and to follow one or other. If I need to reference the studies I can if you want.