Conclusion
Hair loss can be distressing to bariatric surgery patients and many will try nutrition themselves to see if they can prevent it. Unfortunately, there is little evidence that early hair loss is preventable because it is mostly likely caused by surgery and rapid weight-loss.

Later hair loss, however, can be indicative of a nutritional problem, especially iron deficiency, and may be a clinically useful sign. Educating patients about the potential for hair loss and possible underlying causes can help them to make informed choices and avoid wasting money on gimmicks that may have little real value.

Summary:
At any given time most of our hair is in a 'growth phase', but a small percentage is in a 'resting phase'. A number of stressors can cause a greater percentage of our hair to move into a resting phase and WLS patients are at particular risk because we have all had major surgery and experience rapid weight loss which are among the stressors that can impact having a larger percentage of our hair being in the resting phase. Also, if we are experiencing low values of ferritin, zinc or protein or have had more rapid than expected weight loss we may be at greater risk of hair loss.

While some think that supplementing with Biotin, topically or ingesting it; studies have not shown it to be effective in either stopping hair loss or improving regrowth.