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Weight Loss Hair Loss: The Science Behind It

Weight loss hair loss is common among people, especially among bariatric surgery patients. Fortunately, it is mostly temporary. So, with appropriate precautions, it can be prevented, slowed, or stopped.

Weight loss can bring nutrient deficiencies and malnutrition along with it, especially if it’s rapid. And these can cause hair loss because the hair follicles are not getting enough fuel.

Weight loss hair loss happens because of telogen effluvium. It is a form of temporary hair loss. The severity and/or the duration of it can vary from person to person.

This article will focus on these key factors of weight loss hair loss:

  • WEIGHT LOSS CAN INDIRECTLY CAUSE TEMPORARY HAIR LOSS
  • THERE ARE MEDICAL CONDITIONS THAT CAN CAUSE WEIGHT LOSS AND HAIR LOSS
  • THERE ARE WAYS TO PREVENT OR STOP HAIR LOSS WHILE LOSING WEIGHT
  • WEIGHT GAIN CAN CAUSE HAIR LOSS
  • THERE ARE MEDICAL CONDITIONS THAT CAN CAUSE WEIGHT GAIN AND HAIR LOSS
  • OBESITY CAN INDIRECTLY CAUSE HAIR LOSS

Does Weight Loss Cause Hair Loss?

Yes, weight loss with hair loss can occur most of the time. It is mainly caused by nutritional deficiencies. Of course, there may be other factors that should be considered when addressing this issue. These factors can be:

  • RAPID WEIGHT LOSS DUE TO RESTRICTIVE AND/OR MALABSORPTIVE BARIATRIC SURGERY
  • MALNUTRITION DUE TO RESTRICTIVE DIET
  • POORLY BALANCED DIET

Does Weight Loss Affect Hair Growth?

Yes, weight loss can affect hair growth. It can slow the process, meaning there is a connection between hair thinning and weight loss. As the normal amount of 50100 strands of hair falls out daily, the current hair growth rate cannot keep up with it.

Weight loss can cause a change in the hair growth cycle due to certain nutrient deficiencies. It can cause more hair follicles to enter the telogen phase (resting phase). As a result, fewer hair follicles enter the anagen phase (growth phase). This can cause slow hair growth and/or hair loss.

Why Does Weight Loss Cause Hair Loss?

There are a few factors that can play a role in why does your hair fall out when you lose weight. 

  • RAPID WEIGHT LOSS
  • LOW PROTEIN INTAKE
  • VITAMIN DEFICIENCIES
  • RESTRICTIVE DIETS
  • WEIGHT LOSS SURGERIES


Rapid weight loss and restrictive diets along with weight loss surgeries can put quite an amount of stress on the body, which can also cause hair loss.

Can Dieting Cause Hair Loss?

Dieting does not necessarily cause hair loss, provided it has been prepared in consideration of nutritional aspects. If your diet is properly balanced, the chance of experiencing hair loss is slim to none.

However, diets like crash diets or intermittent fasting can cause hair loss due to the insufficient amount of nutrients that the body gets.

Calorie deficit hair loss and crash diet hair loss are easily managed and can be taken care of with proper balancing and adjustment to the diet.

Can A 1200 Calorie Diet Cause Hair Loss?

Yes, a 1200-calorie diet can cause hair loss. Consuming less than 1300 calories increases the risk of telogen effluvium. Especially if it’s lacking essential nutrients like protein, zinc, biotin, etc.

If you are not on a necessary restrictive diet (for example after a bariatric surgery), following a 1200-calorie diet unsupervised is not recommended as you might be losing hair while losing weight along with increasing other health risks.

Can Malnutrition Cause Hair Loss?

Yes, malnutrition causes hair loss as hair needs nutrients to grow healthily through its phases.

If you are following a diet that you know little about, it is possible that you might experience dieting hair loss. For instance, a crash diet can cause hair loss. With crash diets, people change their eating habits drastically, and that causes rapid weight loss. Crash diet hair loss recovery is possible via a proper nutritional program.

Another possible example is intermittent fasting. With this diet, people consume less calories than they should. In this case, intermittent fasting hair loss is inevitable. Hair loss from rapid weight loss can be reversed easily with proper nutrition and supplements.

Can Being Underweight Cause Hair Loss?

Yes, being underweight can cause hair loss. Being underweight can bring other health issues like malnourishment, hormonal imbalances, and overall weak health. These can indirectly affect hair follicles as they are also malnourished in the process. This may cause hair loss.

Can Gaining Weight Cause Hair Loss?

Although there is no direct connection between excess weight and hair loss, gaining weight can cause hair loss.

Excess body fat can cause hormonal imbalances. There can be an increase in dihydrotestosterone (DHT) levels. When DHT levels are increased, hair follicles shrink and that can lead to hair thinning.

Also, for women, excess body fat can cause insulin resistance. This later can lead to PCOS due to high levels of testosterone. This can affect hair growth and cause hair loss.

What Can Cause Extreme Hair Loss and Weight Gain?

Sometimes it is important to consider other factors when it comes to gaining weight and losing hair. As well as there may be lifestyle choices that affect one’s weight and hair loss, there are also medical conditions that may be causing all of this. Causes for hair loss and weight gain can be:

  • CURRENT DIET
  • DIABETES
  • HEART DISEASES
  • IRON DEFICIENCY ANEMIA
  • STRESS
  • THYROID DISEASES
  • VITAMIN B12 DEFICIENCY

Does Obesity Affect Hair Growth?

Obesity does not directly affect hair loss or cause hair loss. However, obesity can lead to several medical conditions. These conditions can affect the hair follicles.

According to a study, obesity can affect hair growth through the depletion of hair follicle stem cells (HFSCs) because of specific inflammatory signals. This affects hair follicles and indirectly affects hair growth and causes hair loss.

Obesity can also lead to heart disease and some medical conditions such as diabetes which causes hair loss. Make sure to consult your healthcare provider to address the issue and act accordingly.

Weight Loss and Hair Loss Symptoms

As you are losing weight, you can observe this loss of hair symptoms:

  • HAIR THINNING
  • HAIR SHEDDING
  • INSUFFICIENT HAIR GROWTH

How to Stop Hair Loss Due to Weight Loss

Hair loss usually stops after a few months. But that does not mean you can’t intervene early. There are a few things you can do to help slow or stop hair loss due to weight loss. Here’s how to stop hair loss after weight loss:

  • ADJUSTING YOUR DIET
  • TAKING SUPPLEMENTS SUCH AS BIOTIN
  • USING NATURAL REMEDIES SUCH AS ROSEMARY OIL (DILUTED) OR COCONUT OIL


⚠️ These methods are
not onesizefitsall methods. Meaning if they work on someone else, does not mean it may work on you. It is important to consult a dermatologist about the matter.

Will Hair Loss from Weight Loss Grow Back?

Yes, hair loss from weight loss will most likely grow back. Weight loss does not damage the hair follicles. They are, in a sense, malnourished. Adjusting your diet can help “feed” the hair follicles, helping them grow hair at their usual pace.

How to Thicken Hair After Weight Loss

There are quite a few ways to thicken hair to help with weight loss hair loss. It can be done by both adjusting nutrition and additional hair care.

There are important nutrients one needs to get in order to promote healthy hair. Protein, for instance, is very important in this matter. Our bodies use protein to produce cells, and that includes hair cells.

Here are the things you can do to thicken your hair:

  • MAKE SURE YOU GET ENOUGH PROTEINS
  • STAY HYDRATED
  • DON’T CAUSE TOO MUCH TRACTION WHILE STYLING
  • DON’T OVERHEAT YOUR HAIR
  • MASSAGE AND EXFOLIATE YOUR SCALP
  • TAKE SUPPLEMENTS 

Minerals and Vitamins to Prevent Hair Loss During Weight Loss

There are essential minerals and vitamins that prevent hair loss and promote hair growth you should pay attention to while losing weight. 

  • VITAMINS B (FOLIC ACID), B-2 (RIBOFLAVIN), 5, 6, 9, AND 12
  • VITAMIN A, C, E, AND D-3
  • BIOTIN
  • IRON
  • ZINC
  • IODINE
  • FERRITIN


Minerals such as iron, zinc, and iodine help hair be
thicker and look fuller. They also give the hair that shiny and healthy look.

How to Prevent Hair Loss During Weight Loss

It is pretty easy and possible to prevent hair loss during your weight loss journey. Let’s examine how to not lose hair when losing weight:

  • AVOID RESTRICTIVE DIETS IF POSSIBLE
  • KEEP IN MIND THAT A DIET THAT WORKS FOR SOMEONE MIGHT NOT WORK FOR YOU
  • CONSULT A SPECIALIST TO PREPARE A WELL-BALANCED DIET PROGRAM FOR YOUR GOALS
  • DON’T FORGET TO HYDRATE
  • TAKE GOOD CARE OF YOUR SCALP AND HAIR
  • DON’T OVERSTYLE, OVERTRACT, OR OVERHEAT YOUR HAIR

Rapid Weight Loss Because Of Weight Loss Surgeries

Hair loss after weight loss surgeries is a common side effect. Weight loss surgeries tend to be restrictive. They limit the amount of food, calories, nutrients, and vitamins that people consume, causing rapid hair loss. Along with these, surgery can put the body under quite an amount of stressThese can cause temporary hair fallout after the surgery.

After most restrictions are lifted after the surgery, the hair will most likely grow back with the additional help of supplements. However, it is important to consult a dietitian about the matter to make sure you are not following an unsustainable diet that makes your body lack essential nutrients, vitamins, and minerals.

  1. Guo, Emily & Katta, Rajani. (2017). Diet and hair loss: effects of nutrient deficiency and supplement use. Dermatology Practical & Conceptual.
  2. Blackburn, G. L., Bistrian, B. R., & Hoag, C. (1977). Hair loss with rapid weight loss. Archives of Dermatology, 113(2), 234.
  3. Zhang, Wen & Fan, Meiling & Wang, Cun-chuan & Mahawar, Kamal & Parmar, Chetan & Chen, Weiju & Yang, Wah. (2021). Hair Loss After Metabolic and Bariatric Surgery: a Systematic Review and Meta-analysis. Obesity Surgery.
  4. Morinaga, H., Mohri, Y., Grachtchouk, M., Asakawa, K., Matsumura, H., Oshima, M., Takayama, N., Kato, T., Nishimori, Y., Sorimachi, Y., Takubo, K., Suganami, T., Iwama, A., Iwakura, Y., Dlugosz, A. A., & Nishimura, E. K. (2021). Obesity accelerates hair thinning by stem cell-centric converging mechanism. Nature, 595(7866), 266–271.