Well I found something that I've had saved on my phone for times exactly like this, I've read it again and it makes me feel a bit better:
STALLS -- WHY THE SCALES CAN LIE
Fat cells are resilient, stubborn little creatures that do not want to give up their actual cell volume. Over a period of weeks, maybe months of "proper dieting", each of your fat cells may have actually lost a good percentage of the actual fat contained in those cells. But the fat cells themselves, stubborn little guys, replace that lost fat with water to retain their size. That is, instead of shrinking to match the reduced amount of fat in the cell, they stay the same size! Result - you weigh the same, look the same, maybe even gained some scale weight, even though you have actually lost some serious fat.
The good news is that this water replacement is temporary. It's a defensive measure to keep your body from changing too rapidly. It allows the fat cell to counter the rapid change in cell composition, allowing for a slow, gradual reduction in cell size. The problem is, most people are frustrated with their apparent lack of success, assume they have lost nothing, and stop dieting.
However, if you give those fat cells some time, and ignore the scale weight fluctuations, your real weight/shape will slowly begin to show. The moral of the story - be patient! Your body is changing even if the number on the scale isn't.
A priority of the human body is survival. Anything that threatens its survival results in the cascade of events to maintain the previous status quo. Water fluctuations are one way the body does this. Brain tells body to produce and release that vasopressin antidiuretic hormone....more water is retained, and no weight loss noticed. Fat loss is still occuring, because ketosis is firmly established and appetite supression is in effect...but water retention is hiding that continuing fat loss. The body is preventing dehydration with this mechanism, and that's a *good* thing.
From the perspective of the scale, it can be discouraging. Which is why the mantra: Water retention masks fat loss (repeated frequently to oneself ) is helpful. Water retention will mask ongoing fat-loss for as long as the body retains the water. We can combat this by drinking more water.
So don't use the scale as an excuse to undermine your progress. Even when the scale is in a stall, fat loss can be occuring.
"Food is not comfort if you're not comfortable!"