What causes hair loss during dieting?

If you’re just starting your weight loss journey, perhaps you have questions about unintentional side effects, such as hair loss. If you’re already well into this journey, maybe you’ve already noticed some thinning of your hair. Either way, it’s important to learn the facts about the connection between weight loss and hair loss and rule out other potential causes.

Diet-Related Hair Loss

Hair follicles are among the most metabolically active in your body. Research shows hair growth can be impacted when you reduce your caloric and/or protein intake or have a micronutrient deficiency. These links are complex, so if you’re suffering from hair loss, your diet could be the cause, but so could other factors. To understand hair loss, it helps to have a basic understanding of the four stages of hair growth:

  1. Anagen phase: During this stage, your hair is continuously growing. About 80-90% of your hair remains in this stage for 2-7 years.
  2. Catagen phase: During this transition stage, which lasts just 10 days, your hair follicles shrink and hair detaches from the blood supply, causing your hair to stop growing.
  3. Telogen phase: During this resting stage that lasts three months, 10-15% of your hair that has detached from the blood supply continues to rest in your hair follicles, with new hair growth beneath it.
  4. Exogen phase: During this shedding phase, it’s normal to lose 50-100 strands a day because some of your hair has completely detached from the follicles.

Hair Loss After Weight Loss

Your body needs adequate calories and protein to feed your hair follicles. According to some experts, the more weight you lose, the more likely you’ll experience some degree of hair loss. Losing and regaining weight over many years can impact your metabolism and hair growth. Some people may experience hair loss within 3-6 months of starting diets (e.g. keto). Typically temporary, a balanced, healthy diet should reverse hair loss within six months.

Hair Loss Dieting Research

An acute form of the condition telogen effluvium (TE) is a well-known side effect of sudden weight loss or decreased protein intake. This condition, which causes thinning or shedding hair, occurs when your hair prematurely enters the telogen phase. Dieting can cause physical and emotional stress, thereby causing more hair than usual to enter the telogen phase.

Protein deficiency: This can impact your skin, hair and nails because they are made primarily of protein. Protein is essential for hair growth, so a lack of healthy protein in your diet can cause broken hair strands that are resistant to growing back.

Iron deficiency: The most common nutritional deficiency worldwide, this is a well-known cause of hair loss. It’s unclear what degree of deficiency leads to hair loss and studies are inconclusive. Risk factors include menstrual blood loss, malabsorption (e.g. celiac disease), the use of H2 blockers and a vegan or vegetarian diet.

Zinc deficiency: This essential mineral is important for the health of your skin and hair, among other key body functions. Although this type of deficiency is fairly uncommon, risk factors include aging, gastrointestinal disease, anorexia, malabsorption, chronic liver or renal disease, sickle cell disease, diabetes, cancer, alcoholism and a vegetarian diet.

Vitamin D deficiency: Vitamin D stimulates the growth of new hair follicles, therefore experts believe a deficiency can cause hair loss or thinning. The strongest evidence shows a link between a vitamin D deficiency and alopecia areata, an autoimmune condition that causes patchy hair loss.

Hair Loss Prevention Tips

  • Avoid diets that restrict calories too severely
  • Add a variety of healthy proteins to your diet to help improve the production of amino acids needed to produce keratin
  • Eat plenty of whole grains, fruits and vegetables
  • Get adequate sleep (about 7 to 8 hours a night)
  • Take a high-quality multivitamin that provides at least 100% of the recommended daily value needed to keep you healthy, vibrant and happy

While your hair loss may be related to nutritional deficiencies from being on a diet, it’s important to consult your doctor before taking supplements other than a multivitamin. Your medical history and a physical exam will help your doctor pinpoint whether genetic disorders, medical conditions or dietary practices are responsible for your hair loss.