The ketogenic diet (keto) is a weight-loss approach that radically shifts the body’s primary fuel source by requiring a very low intake of carbohydrates, moderate protein, and high dietary fat. This structure forces the body into ketosis, a metabolic state where it burns fat for fuel instead of glucose. For individuals new to this diet, increased hair shedding can be a concerning side effect. Hair loss can occur, but it is usually temporary, related to the body’s initial adaptation to the sudden change in metabolism and nutrient intake.
The Physiology Behind Temporary Hair Loss
The body perceives any rapid, significant shift in its internal environment, such as a drastic reduction in caloric intake or a major metabolic change, as a form of physical stress. This stress can trigger a temporary hair loss condition known as Telogen Effluvium (TE). TE occurs when a higher-than-normal percentage of hair follicles prematurely exit the active growth phase (anagen phase) and enter the resting phase (telogen phase).
Hair follicles that enter the telogen phase stop growing and are typically shed about two to four months after the initial stressor occurs. This explains why hair shedding often begins weeks or months after someone starts the keto diet, rather than immediately. The rapid weight loss often experienced in the first few weeks of keto, sometimes due to water loss, is also a significant physiological stressor contributing to this effect.
The body prioritizes energy use for essential functions like organ operation and survival during times of stress or insufficient energy intake. Hair growth, which is a non-essential process, receives fewer resources, causing the follicles to shut down and enter the resting phase. Because TE is a reaction to a temporary stressor, the shedding is generally reversible once the body adjusts and the source of the stress is removed or mitigated.
Nutritional Imbalances Specific to Ketosis
Beyond the general stress response, a poorly planned ketogenic diet can exacerbate hair loss by introducing specific nutritional deficiencies. Hair is primarily composed of protein, and inadequate protein consumption can directly impair the hair growth cycle. Some keto protocols limit protein intake out of concern that too much protein might interfere with ketosis, inadvertently starving the hair follicles of their essential building blocks.
The highly restrictive nature of the keto diet, which eliminates many whole food groups like grains, legumes, and most fruits, can lead to micronutrient shortfalls. Insufficient intake of B vitamins, particularly biotin, is frequently observed because these vitamins are necessary for converting food into the energy needed for hair growth. Biotin is involved in the synthesis of keratin, the protein that makes up hair structure.
Deficiencies in essential minerals like iron and zinc can also compromise hair health. Iron is necessary for the production of hemoglobin, which carries oxygen to the hair follicles, and low levels can induce TE. Similarly, zinc plays a role in hair tissue growth and repair, and a deficiency can lead to hair thinning and breakage.
Strategies for Minimizing Shedding and Supporting Regrowth
To minimize hair shedding, one of the most immediate strategies is to ensure the caloric deficit is not too severe, which reduces the body’s perception of stress. Individuals should calculate their protein needs carefully, aiming for moderate, not minimal, intake to supply the amino acids required for hair structure without compromising ketosis. High-quality protein sources like grass-fed beef, fatty fish, and eggs should be prioritized.
Targeting specific keto-friendly foods can help address potential deficiencies in key micronutrients. For instance, incorporating foods rich in zinc, such as pumpkin seeds and grass-fed beef, and iron-rich options like liver and spinach, can support follicle health. Many B vitamins, including biotin, can be sourced from eggs, salmon, and nuts.
In cases where diet variety remains limited, a broad-spectrum multivitamin or targeted supplements for biotin, zinc, or iron may be considered, but only if a deficiency is suspected. The hair loss caused by TE is typically temporary, with the shedding phase resolving and regrowth beginning within three to six months after the body stabilizes and nutritional deficits are corrected. If hair loss persists or is accompanied by other symptoms, seeking medical consultation is advisable to rule out underlying non-dietary causes, such as thyroid dysfunction.