St. Patty's Day Disaster

We attended our church supper for St. Patrick's Day, offering a delicious stew, salad, and dessert.  I had a bowl of stew with big pieces of beef, thick gravy, potatoes, and carrots. I realized the stew wasn't legal for low carb, but I was not prepared to eat just salad (am I too cheap, needing full value for my money?).

I had a plate of salad, and skipped the dessert.  I wisely chose a second helping of salad instead of more stew.  I left full, but not over full.  Late that night, I had cravings & the munchies, and got into peanut butter on Triscuit crackers.  Was this the carbs talking, where the rush of insulin crashed blood sugar, causing me to need to eat?

The next morning I woke up to find myself 4.6 lbs heavier than the day before.  Ouch!

I ate 100% on low carb that day.

Next day, when I weighted in, I had lost 6.2 lbs.  This means I lost the 4.6 lbs I had gained the previous day, plus another 1.6 lbs.  Thank goodness!

That was quite the rollercoaster.  Has anybody else had a similar experience.  Can I assume that the diet violation really packed on the weight, then I lost it again really quickly?  The scale's %fat and %water shows that I gained 1.89 lbs of fat from St. Patty's Day feast, plus 1 lb of water.

It is a known feature of carbs in a diet that they cause you to gain & retain water.

So if I gained 1 lb of water and 1.89 lbs of fat, for a total gain of 2.89 lbs, how come the scale went up by a total of 6.2 lbs?  Is the only other component bone mass?  I suspect we are seeing inaccuracies in the scale for weight, %fat, %water, or all three.