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A good test to determine if you are undereating to lose?

In learning about the issue of glycogen and water and how that can cause the appearance of rapid weight gain after a "day of indulgence", it occurred to me that perhaps this provides a way to test whether one is, indeed, eating too few calories for ideal weight loss.

Let's say that I have a goal of 1300 net calories per day. I'm losing weight but worry that I may be in too big a caloric deficit because maybe my weight loss is a bit too fast (and normally I'd be delighted but I'm getting an education on MFP). If I am, in fact, depleting my glycogen stores significantly then, in theory, I could test that by deliberately overeating one day and checking to see if I gain a few pounds the next morning. Right?

And if so, how much of an "instant overnight weight gain" would indicate this? E.g. if I gained 5 lbs the next day, would that suggest my glycogen was too depleted?