Can Not Eating Enough Calories Make Your Hair Fall Out?

According to dermatological studies, restrictive diets and severe calorie deficits are common triggers for a temporary hair loss condition called telogen effluvium. This happens because when you are not eating enough calories, your body redirects energy away from non-essential functions like hair growth to preserve vital organ function.

Quick Summary

This article explores how severely restricting calories or crash dieting can lead to temporary hair loss by causing nutrient deficiencies and triggering stress responses. It details the key nutritional needs for healthy hair and offers guidance on how to promote regrowth through a balanced diet and healthy lifestyle choices.

Key Points

• Low Calorie Diets Can Cause Hair Loss: Severely restricting calories triggers a survival response in the body, which redirects resources away from non-essential functions like hair growth, leading to shedding.

• It's Called Telogen Effluvium: This type of temporary hair loss is a condition where more hair than usual enters the shedding phase due to a stressful event, like rapid weight loss or malnutrition.

• Nutrient Deficiencies are the Root Cause: Restrictive eating can lead to deficiencies in key nutrients vital for hair health, including protein, iron, zinc, and certain vitamins.

• Gradual Weight Loss is Safer: Rapid, crash dieting puts more stress on the body and is more likely to cause hair loss than a slow, sustainable approach.

• Hair Loss is Often Reversible: By addressing the nutritional deficits with a balanced diet, hair loss caused by inadequate calorie intake can typically be reversed, though it requires time and patience.

• Patience and a Balanced Diet are Key: Promoting regrowth means focusing on eating enough lean protein, iron, and zinc, and managing stress. New growth may take several months to become visible.

The Connection Between Calorie Restriction and Hair Loss

When you intentionally or unintentionally consume significantly fewer calories than your body needs, it triggers a survival response. Your body perceives this as a state of famine and begins to allocate resources to the most critical functions, such as keeping your heart and brain operating correctly. Unfortunately, hair growth is considered a non-essential biological process, so hair follicles are among the first areas to suffer from reduced energy and nutrient supply.

This process often leads to a condition called telogen effluvium, where a large number of hair follicles are pushed prematurely from the active growth (anagen) phase into the resting (telogen) phase. Typically, it takes about two to four months after the initial stressor—in this case, calorie restriction—for the hair to begin shedding excessively. The hair loss is often noticeable and can affect the entire scalp rather than appearing in specific bald patches.

Critical Nutrient Deficiencies Caused by Low-Calorie Diets

Not only does low-calorie intake reduce overall energy, but it also increases the likelihood of specific vitamin and mineral deficiencies that are critical for hair health. The following are among the most commonly affected nutrients:

• Protein: Hair is made almost entirely of a protein called keratin. When your diet lacks sufficient protein, your body cannot produce enough keratin, leading to weaker, more brittle hair that is prone to breakage and shedding.
• Iron: This mineral is vital for carrying oxygen to all cells in the body, including the hair follicles. An iron deficiency can disrupt the hair's growth cycle. Research has shown that many women experiencing hair loss have low iron stores.
• Zinc: An essential mineral for cell growth and repair, zinc deficiency can lead to significant hair shedding. Zinc also helps maintain the oil glands around the hair follicles.
• Biotin (Vitamin B7): This B-vitamin is crucial for keratin production. While a deficiency is rare in those with a balanced diet, it can lead to hair thinning and is often a focus in cases of hair loss associated with malnutrition.
• Vitamin D: Often functioning as a hormone, Vitamin D plays a role in the formation of new hair follicles. Low levels of vitamin D are frequently observed in people with hair loss conditions, including female pattern hair loss and alopecia areata.

The Impact of Rapid vs. Gradual Weight Loss

How quickly weight is lost can significantly influence the risk of hair shedding. Rapid or "crash" dieting puts the body under immense physical and emotional stress, making hair loss more probable. In contrast, a more gradual and sustainable approach to weight loss allows the body time to adapt without causing a severe shock to its systems. The table below compares the typical hair-related outcomes of these two methods.

Feature	Rapid/Crash Dieting	Gradual/Sustainable Weight Loss
Calorie Intake	Severely restricted, often under 1,200 calories daily.	Modestly reduced, creating a slight deficit over time.
Nutrient Availability	High risk of deficiencies in protein, iron, zinc, and vitamins due to limited food intake.	Better potential to meet nutritional needs through a balanced diet, minimizing deficiency risks.
Stress on Body	High stress, which can trigger telogen effluvium, leading to excessive shedding.	Minimal stress, allowing the body to adjust without disrupting the hair growth cycle.
Hair Shedding	Often significant and noticeable, occurring 2–5 months after the diet begins.	Less common, but possible if diet is not well-managed.
Reversibility	Usually reversible once nutrition is restored, though it takes time.	Highly reversible with minimal or no noticeable hair loss.

Promoting Hair Regrowth After Nutritional Deficit

If you have experienced hair loss due to not eating enough calories, the good news is that it is often reversible by correcting the underlying nutritional issues. The recovery process requires patience, as hair growth is a slow cycle. It can take three to six months for shedding to normalize and new hair growth to become noticeable.

To promote regrowth, focus on a well-balanced diet rich in the following nutrients:

• Lean Proteins: Include foods like chicken, fish, eggs, and legumes to provide the building blocks for keratin.
• Iron-Rich Foods: Incorporate spinach, lentils, red meat, and fortified cereals. Pair these with Vitamin C-rich foods like citrus fruits to enhance absorption.
• Zinc Sources: Boost your intake of pumpkin seeds, nuts, beef, and chickpeas to support hair follicle health.
• Vitamin D: Get sufficient sun exposure and eat foods like fatty fish, eggs, and fortified dairy.
• Hydration: Drinking plenty of water is essential for overall health, including keeping your scalp hydrated and supporting nutrient delivery to your follicles.

For some, particularly those following a vegetarian or vegan diet, a healthcare provider may recommend targeted supplements to address specific deficiencies. Regular scalp massages can also help by improving blood circulation, which delivers more nutrients to the hair follicles.

Conclusion: Prioritizing Nutrition for Hair Health

Not eating enough calories can indeed make your hair fall out, primarily by triggering telogen effluvium and causing deficiencies in vital nutrients like protein, iron, and zinc. The body’s survival response diverts energy from non-essential functions, slowing or stopping hair growth. Rapid, restrictive diets increase this risk compared to gradual, sustainable weight loss. The condition is often temporary and can be reversed by adopting a balanced, nutrient-rich diet. For best results, consider consulting a healthcare provider to rule out other medical conditions and to develop a personalized nutrition plan to support healthy hair growth.

How to get help for hair loss

If you are experiencing significant hair loss and suspect a nutritional cause, it is important to seek professional help. A dermatologist or a registered dietitian can assess your specific situation. This may involve blood tests to identify any underlying deficiencies and help create a tailored diet plan. For those with underlying eating disorders, professional psychological support is crucial for both overall health and hair recovery.

How to promote hair regrowth naturally

• Diversify your diet to include a wide range of nutrient-dense foods like fruits, vegetables, nuts, and lean proteins to ensure all essential micronutrients are covered.
• Manage stress with techniques such as yoga, meditation, or regular exercise, as high stress levels can exacerbate hair shedding.
• Be gentle with your hair, avoiding harsh chemical treatments, excessive heat styling, and tight hairstyles that pull on the roots.
• Consider a scalp massage to improve circulation and promote nutrient delivery to the hair follicles.

By taking a comprehensive approach that prioritizes both adequate calories and balanced nutrition, you can address the root cause of hair loss and support the return to a healthy, full head of hair.

Visit Healthline for more detailed information on how diet affects hair loss.

Frequently Asked Questions

How soon after starting a low-calorie diet can hair loss occur?

Hair loss typically begins two to four months after the onset of a major dietary or caloric restriction. This delayed response is due to the natural cycle of hair growth, as the hair follicles take time to transition into the shedding phase.

Will my hair grow back if I start eating normally again?

Yes, in most cases, hair loss caused by calorie restriction is reversible. Once you restore your nutrient intake with a balanced, healthy diet, your hair should begin to regrow. The recovery process, however, is gradual and can take several months.

What kind of foods should I eat to prevent or stop hair loss from a poor diet?

Focus on a diet rich in lean proteins (fish, eggs), iron (spinach, lentils), zinc (nuts, seeds), and vitamins like C and D. Adequate protein is essential, as hair is primarily composed of it. Combining iron-rich foods with Vitamin C aids absorption.

Is it possible to have hair loss from dieting without being underweight?

Yes, it is possible. Hair loss can be triggered by the body's stress response to rapid weight loss or nutrient deficiencies, even if you are not clinically underweight. The key trigger is the sudden and severe reduction in calorie and nutrient availability.

Can taking supplements alone fix diet-related hair loss?

While supplements can help address specific nutrient deficiencies identified by a doctor, they are most effective when combined with a balanced diet. Supplements should not replace whole foods. It's crucial to consult a healthcare provider before starting any new supplement regimen.

How long does it take for hair to recover after a nutritional deficiency is corrected?

The timeline for recovery varies but is typically slow. You may start to see less shedding within a few months, with new, noticeable hair growth taking six to twelve months of consistent healthy eating and nutrient intake.

Can stress also cause hair loss during dieting?

Yes, stress is a major contributing factor. The physical and psychological stress of restrictive dieting can trigger telogen effluvium. Managing stress through exercise, mindfulness, or other coping mechanisms is important for both overall health and hair recovery.