Here is his post. the part in red about the balloon in the band being semi-permeable might explain why I have problems when I fly.
"Often times patients will come in because their band feels too tight. They find more difficulty with some foods, and are uncomfortable. They ask me “does stress cause the band to tighten?” The answer is, yes, it does.
The biology of stress is this: when you have stress, be it physical stress (like an illness) or mental stress (like your mother-in-law coming by for a short two week visit)…the body reacts by retaining fluid. You may notice that wedding rings are tighter, and there is more swelling in the legs at night.
The balloon of the band is a semi-permeable membrane, meaning it is osmotically active. In plain English: the more water you retain, some is transmitted to the band, so it swells.
If a patient has 5.5 cc in their band (we measure it) and they come in and it feels tighter, we find they have 6 cc in the band. Where did the ½ cc come from? That is from the extra water the body is carrying. Since the balloon on the band is semi-permeable it will retain more water also.
This is the same reason that most people find the band to be tighter in the morning. In the evening you may notice you have some swelling of your ankles – by gravity your body water has gone down to the legs. In the morning that swelling is gone, and the water has gone back to the central compartment of the body where the band is. If we measure the band in the morning it can have 0.25 to 0.5 cc more in it (which can make a difference).
This is also why we don’t like bands being too tight. People need room for stress – of all kinds. Leaving room in the band to allow for this, means that patients will have fewer difficulties."
Huh. You learn something new everyday.