In college and graduate school, preparing for long overseas stays, I had my height measured at campus medical offices and I was 5'6". but around twelve years ago, I was 5'5", as measured in a number of doctors' offices. That continued up to my August, 2010, physical.
To my surprise, last November, 2011, my doctor's office found me to be 5'6". And this month I am 5'7". They measured me on two different machines, just to be sure.
I am past the age when people grow. I have always had good posture, and am not aware of any changes in how I stand — either at the doctor's or in general. I have worked standing for most of the time since 1997.
My doctor said, "This doesn't happen, but it happened." His only idea was that exercise might have subtly altered my posture.
Two years ago I began exercising fairly seriously — mainly on an elliptical machine. There are something over 20 free vertebrae, plus the knee joint. If each joint has stronger musculature and is able to be held just two mm. further apart when I am standing at attention, that would round up to two inches' increase in height.
I have done nothing special for my diet in this time — I have eaten mostly fish, fruit, nuts, green stir-fryable vegetables, whole grains, and cheese for many years, with the occasional bacon double cheeseburger, cheese pizza, or chocolate bar when feeling stressed. I have rarely gotten what I felt was enough sleep.
I'll continue to exercise but I predict I will never make it to 5'8". Anyway, I am perfectly satisfied being considered short in this society, and have never craved height.