Um... Stop eating carbs?
LOL. Actually, it always makes me smile when people are surprised to gain weight when they've eaten carbs.
Like you, I don't know what the official term is - or even if there
is one. But what I do know is that when you eat carbs, you fill up your glycogen stores - and as glycogen holds 3-4 times its own weight in water with it, the scales can bounce up considerably even if 'all you've done' is eat a roast dinner at your Mum's on Sunday.
I rather think though, that the number you see on the scales after eating that meal is your 'proper' weight. If you're on a low carb diet, your weight is always going to be anything from around 5 - 9 pounds lower than what it is eating a non-low carb diet. If you're on a low carb diet, that glycogen store is always going to be depleted. The moment you introduce carbs it's gonna fill straight back up (together with water). It's just the way it is.
That's why, at the end of doing SS, it's best to work your way back up the steps, reintroducing carbs and calories gradually - so that in effect, you don't
notice the glycogen store refilling (because your calorie intake is still low in the early stages, say on 810 - you're still losing weight). I'm not sure that I've explained that all that well
but that's my understanding of it.