I've had that problem too, but I was also in keytosis at the time and not loosing.

Ok, first of all...watch the water intake. That's a big important one. I drink over 64 ounces a day. What some people will do is take a water bottle and wrap rubberbands around it to represent the amount of water left to drink. Once you've cleared one bottle, take off a rubber band. It seems easier to keep up with the water that way. While some will fill up a gallon jug and when it's empty, they know they've gotten to their water goal.

Also, is your wife drinking diet soda? I've noticed NutraSweet, Aspertame, will knock me out of keytosis at the drop of a hat, but Splenda won't.

Is she eating any of the low carb packaged foods? If she's eating a lot, those too can be a culprit.

Sometimes even decaf coffee will ease up my keytosis. Green tea too as it has a little caffine.

Not much else I can think of right now. I hope this helps.