Did you drink 2 lbs of fluid? I can go on a 4-5lb swing in a day just depending on the timing of drinking water and urinating. You might want to consider adding some electrolytes to your water once in a while. It can help prevent the body from holding on to excess water.
Check out the website Diet Doctor. They aren’t tied to any companies and mainly provide tons of information on paleo & ketogenic diet and explains certain food you should avoid if trying to lose weight. There are loads of recipes and meal planning! I’ve lost 25 lbs thanks to finally getting all the hidden ‘sugar & fillers out of my diet. It’s amazing how sneaky the food industry is in trying to keep sugar addicted customers and hiding all the bad oil and sugar! Anyway, good luck…