Hair Loss and how to avoid it
During the phase of rapid weight loss, calorie intake is much less than the body needs, and protein intake is marginal. The body is in a panic mode, like what would happen during a period of starvation. One of the side-effects, in some persons, is inactivation of 30 - 40% (rather than the usual 10%) of hair follicles, causing noticeable amounts of hair to fall out. This is a transient effect, and resolves when nutrition and weight stabilize.
Hair loss usually occurs in the fourth of fifth month following weight loss surgery. Be sure of adequate protein intake. Sometimes a zinc supplement will help.