Hi Cate, I meant to write to you about the extra kg gained back. I struggle with even staying the same weight and it being an excuse for my ego to say, "what's the use, this is not working, just comfort yourself with a little of this fattening food here. Oh, and why bother exercising?"
I tend to fluctuate 1-3 pounds naturally when dieting. So I think of a pound lost as the new low weight to stabilize toward. I usually lose a pound and then gain it back and try to stay really conscious that this is normal and not to get discouraged, and then I work extra hard to eat extra healthy and exercise a normal amount so that the pound comes off permanently. I think of it as punching through the barrier of the old weight by losing a little and then working at maintaining that weight loss permanently. Like yesterday I planned to move furniture back in to our remodeled part of the house as my exercise, which may have helped stabilize my recent weight loss, but instead we went to the city and ate fattening, salty Filipino food and went to an improv show. It was also almost 100 degrees, so I drank a ton of water, so the pound I gained back yesterday could be part water weight, too.
So I really try to think of the first time I reach a new low weight as just the punching through of the old plateau and then work hard to keep the weight loss in the next days after that. I really focus on it as a positive sign that I lost the pound, but I don't count on it staying off until I have weighed the new weight for 3 or 4 days in a row. So I hope you don't give in to the discouragement - it's a very positive thing that you did drop a kg, and I bet it means that when you go back to your normal routine or a slightly more rigorous routine, you can keep it off permanently!
I just looked up water retention, and found a good paleo-inspired article on it, and it says that water retention can be caused by elevated cortisol levels, among other things. "All kinds of things can raise cortisol levels, including calorie restriction and strenuous exercise – the exact behaviors that most people turn to for weight loss. Sleep deprivation or psychological stress will also do the trick (
https://paleoleap.com/everything-you-need-to-know-about-water-weight/ ). So we have to be careful not to stress about slight weight gains and cause further water weight gain that freaks us out even more!!