When a patient presents with hair loss on an obesity medicine board question, the knee-jerk reaction is to suspect a vitamin or mineral deficiency. While that may be the correct answer, other differentials should be considered. Hair loss is a common complaint in obesity medicine. In this blog, we will discuss another etiology to consider.

Telogen effluvium is a form of diffuse, nonscarring (i.e., hair follicles are not irreversibly damaged and thus can potentially regrow) hair loss that often is transient, although it can continue into a chronic phase in some cases. This occurs when a significant number of hair follicles prematurely enter the resting (telogen) phase of the hair growth cycle, leading to increased hair shedding. Normally, hair would cycle through a growth, transformation, and rest phase, spending most of its time in the growth phase (2-7 years long), before entering into the short transformation phase, followed by the final three-month rest phase (telogen). At the end of the telogen phase, the hair sheds, and the hair follicle restarts the process with a new strand of hair. This cycling is asynchronous and independent of other hair follicles, meaning that only a small percentage (<10%) are ever in the telogen phase simultaneously. An average of 100 hairs are shed daily, which is not significantly noticeable, with an average of 150,000 total hair follicles.

In telogen effluvium, a much higher percentage (up to 35%) of hair follicles synchronously enter the rest phase earlier than intended. Therefore, much more hair sheds in a short amount of time. The physiologic trigger that causes this condition is often caused by a large stress factor such as a major surgery, childbirth, a big life event causing emotional distress, serious illness, nutritional deficiencies, or rapid weight loss. However, nearly 1/3 of patients experiencing this have no identifiable inciting factor. Most patients will notice a more diffuse pattern of hair loss, although the bitemporal areas tend to be more noticeable. Women are more commonly affected compared to men

Improvements are usually seen over time (6-12 months), especially as the length of time from the inciting event increases. Reassurance is often all that is needed, as other therapies, such as minoxidil, have mixed evidence as a treatment option, although it may make the hair loss less noticeable. Importantly, in the world of obesity medicine, it is our job to ensure that there are no secondary causes of hair loss, such as lack of nutrition or minerals. Some fad diets and very low-calorie dietary plans may induce a rapid caloric and micronutrient deficiency that should be addressed. Ensuring patients are getting adequate protein and consuming adequate vitamins in those after metabolic and bariatric surgery is vital. For example, zinc deficiency leading to alopecia is relatively common and may also present with concurrent loss of taste or smell. In addition, biotin, iron, niacin, and protein deficiency all have the potential to cause increased hair loss.

Be aware of this relatively benign (medically, not emotionally) etiology of hair loss in those undergoing significant weight loss, either medically or surgically. An uptick in this condition is being seen with the more efficacious anti-obesity pharmacologic therapies. Expect to see this condition as an answer option or a distractor on test day.

Sample Question:

A 51-year-old woman presents for follow-up after undergoing a single anastomosis duodeno–ileal bypass with sleeve gastrectomy three months prior. She has lost nearly 43 lb (19.5 kg) and has noticed significant improvements in mobility given her decreased knee pain. Her blood pressure decreased and she no longer is taking losartan. She is taking her recommended bariatric vitamins daily and following all protein and fluid recommendations by the dietitian. Her only complaint today is hair loss. Which of the following is the best next step in management?

A. Provide reassurance

B. Order zinc levels

C. Start taking biotin supplementation

D. Refer back to the dietitian

Next Week: Intensity of exercise/METS

Following: Monthly Knowledge Check. This is a review checklist of must-know items for ABOM exams based on the previous four blog topics (Updated pediatric guidelines, PCOS, telogen effluvium, intensity of exercise/METS). In addition, this will include a brief explanation of the correct answers to previous sample questions.

Upcoming weeks: Endoscopic gastroplasty, Cohen’s syndrome, hormonally active adipose, and metabolic syndrome

For more practice questions, check out the following:

  • Obesity Medicine Board Review Questions (2026): Qs 215 and 255.
  • Obesity Medicine Practice Tests (2026): Q 335.

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