This article is for health education purposes only and is intended for informational reference; it does not constitute medical advice. If you have any health concerns, please consult a professional physician.

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First, a question: when you washed your hair recently, were there more hairs on the drain than before?

Once Bailu (White Dew) has passed and the weather turns cooler, many people start saying, "I lose hair every autumn." Don't rush to change your shampoo, and don't blame it all on staying up late—for a considerable number of people, this is a "seasonal molt" that the body stages once every autumn, and it may not count as hair loss at all.

A 6-year study at the University of Zurich Hospital in Switzerland tracked 823 healthy women who complained of hair loss: the results showed that the proportion of hairs in the telogen (resting) phase peaked in summer and was lowest in late winter [1]. After hair enters the telogen phase, it takes about 3 months before it sheds—so the batch of hairs quietly "queuing up" in summer often leaves in a concentrated wave in late summer and early autumn. More hair falling out in autumn really isn't your imagination.

1. First, distinguish: is this "molting" or "hair loss"?

Hair follicles have their own rhythm: anagen (growth), catagen (transition), and telogen (resting), cycling over and over. When the proportion of telogen hairs rises and they then shed in a concentrated wave, medicine calls this telogen effluvium, the most common cause of diffuse hair shedding [4].

Its typical features are clear: uniform thinning across the whole scalp, with shedding especially obvious when washing or combing; the scalp is not red, painful, or itchy; and the shedding often only becomes apparent 3-4 months after the trigger appears—this time lag leaves many people unable to connect the dots [4].

2. A trigger more worth watching than autumn: rapid weight loss

"Sudden weight loss or a sharp drop in protein intake can trigger acute telogen effluvium"—this is a plainly stated line from a dermatology review [2]. An extreme reference point is the bariatric surgery population: a meta-analysis pooling 18 studies and 2,538 people showed that the incidence of postoperative hair loss was about 57%, and was more pronounced in those with low ferritin, zinc, and folate; moreover, the longer the follow-up, the lower the incidence, suggesting that most cases are temporary [3].

In another prospective study of 50 people, 56% experienced hair loss 6 months after surgery, and those who shed had lower zinc and vitamin B12 levels [5]. Ordinary people dieting to lose weight need not take this personally—but the logic of how extreme weight loss of the "lose a dozen-plus jin in a month" kind impacts hair follicles is the same.

3. The nutrients hair needs: protein, iron, zinc

Hair is mainly made of protein; and iron deficiency is a globally prevalent nutritional problem and a known cause of hair loss [2]. If during weight loss you eat only boiled vegetables and hardly touch meat, eggs, or dairy, protein and iron can easily fall short, and your hair will naturally be the first to "go on strike."

One reminder: supplements are not better the more you take. In the available evidence, supplements help only people who are genuinely deficient [2]. Rather than blindly buying all kinds of "anti-hair-loss gummies," ask yourself first: have I had enough meat, eggs, dairy, and beans today?

4. Do these three things right, and leave the rest to time

  • Aim for steady weight loss: don't chase losing several jin in a week; give your body time to adapt;
  • Eat enough basic nutrition: lean meat, eggs, dairy, soy products, and dark leafy greens—include them every day;
  • Set a stop-loss line: if shedding persists for more than 3 months without easing, patches of hair fall out, or the scalp shows redness, see a dermatologist to rule out endocrine, nutritional, and other causes [4].

Forward this to the friend who keeps saying "I'm going bald"—more hair falling out in autumn is mostly the body changing its hair with the seasons; what really needs guarding against are those extreme weight-loss methods that "starve" your hair. You may also want to save this card and use it for a self-check.

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Disclaimer: This article is for health education purposes only and is intended for informational reference; it does not constitute medical advice. If you have any health concerns, please consult a professional physician. Conflict of interest statement: This article involves no commercial promotion; all content and data come from publicly published research and guidelines.

References

[1] Kunz M, Seifert B, Trüeb RM. Seasonality of hair shedding in healthy women complaining of hair loss. Dermatology. 2009;219(2):105-110. PMID:19407435

[2] Guo EL, Katta R. Diet and hair loss: effects of nutrient deficiency and supplement use. Dermatol Pract Concept. 2017;7(1):1-10. PMID:28243487

[3] Zhang W, Fan M, Wang C, et al. Hair Loss After Metabolic and Bariatric Surgery: a Systematic Review and Meta-analysis. Obes Surg. 2021;31(6):2649-2659. PMID:33675022

[4] Malkud S. Telogen Effluvium: A Review. J Clin Diagn Res. 2015;9(9):WE01-3. PMID:26500992

[5] Katsogridaki G, Tzovaras G, Sioka E, et al. Hair Loss After Laparoscopic Sleeve Gastrectomy. Obes Surg. 2018;28(12):3929-3934. PMID:30062467

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