Weight loss and hair loss may be connected in a number of ways. Hair loss may be caused by the physical stress the body goes through when significant weight is rapidly lost. Malnutrition caused by dieting can also be a factor in thinning hair, as can hormonal imbalances, such as a thyroid disorder.
Hair growth occurs in cycles. The hair on one’s head will actively grow for two to three years, followed by a resting period; the hair then falls out and is replaced by new hair, which begins the cycle again. This cycle may be disrupted by any number of factors, including malnutrition and stress, that make the hair reach its resting stage prematurely, and thus increased hair loss may occur. If hair loss is due to factors such as emotional stress or diet, hair growth will typically return to normal when the body reaches a more stable state. Stronger hairs will typically replace the lost hair, creating a fuller-looking and healthier head of hair.
One major connection between weight loss and hair loss is stress, either physical or emotional. Hair loss has been known to occur when an individual has experienced a death in the family or is recovering from some sort of emotional trauma. Physical stress may also create conditions for hair loss. Physical stress could involve an illness or surgery and could also include sudden weight loss. When individuals experience stress, their bodies stops expending energy on hair growth in order to use that energy elsewhere. When the stress stops, normal hair growth usually resumes.
Poor nutrition that may be caused through dieting may also cause hair loss. A lack of nutrients may cause thin hair, brittle or weak hair, or general hair loss. Protein is an especially relevant nutrient for hair health. A doctor should be consulted before beginning a diet to ensure the diet is balanced and nutrient-rich.
Another connection between weight loss and hair loss is iron. Even if a weight-loss diet is gradual and not causing a great amount of stress to the system, a change in diet may involve a decrease in the intake of iron. Iron deficiencies have been linked to hair loss, especially in women. Women suffering from thinning hair may best investigate their iron intake.
Weight loss and hair loss may also be linked in that they may both be caused by a hormonal imbalance, such as can be caused by a thyroid disorder. The hormones the thyroid produces regulate metabolism, and an imbalance in the gland may cause either weight loss or weight gain, along with hair loss. Hair loss may also be accompanied by a change in hair texture — it may become brittle or weak. Thyroid disorders are often easily treated through medication.