When it comes to growing healthy hair and nails, you’ve probably already seen all the ads for supplements containing certain nutrients that can help, such as vitamins A, E and D, along with iron, fats, carbs and protein. You’ve probably also heard about biotin, a B vitamin, that can help.

But there’s another key, and you’ll probably like it more — two words: eating enough.

It plays a bigger role than you may realize, too. “Our hair and nails are among the first signs of poor nutrition and/or nutritional deficiencies because hair and nail cells have a rapid turnover rate,” said Shelley Balls, a registered dietitian and nutritionist (RDN) for Flawless Bloom.

How is that the case, though, and what does it look like in practice? We talked to registered dietitians and dermatologists to find out.

How A Healthy Diet Aids Nail And Hair Growth

In the same way that your body needs calories and nutrients for cognition, organ function and moving around, it also needs calories to help your nails and hair grow. Not enough food means not much (or any) growth.

“If you’re under-eating, your body doesn’t have enough energy to use for all of its processes, including hair and nail cell growth and regrowth,” said RD Caroline Young, owner of Whole Self Nutrition. “Under-eating can also lead to nutritional deficiencies, which can negatively impact hair and nail growth.”

After all, other body parts obviously have priority when your body is running on limited calories.

“The body prioritizes its vital organs, sending nutrients there first to ensure you can keep functioning,” said Dr. Anna Chacon, a board-certified dermatologist. “Improper nutrition can cause [hair and nail] shedding, brittleness and eventually loss if not properly cared for.”

From a related perspective, it’s necessary to consider what nails and hair are made of at a compound level. “Your hair and nails are both made of keratin, which is a protein your body produces,” said Dr. Allison Leer, a board-certified dermatologist and co-founder at Botanist, a woman-led nail product company. “Creating keratin requires energy in the form of calories and other nutrients to support the protein synthesis.”

Dr. Stephanie Taylor, a board-certified dermatologist and senior consultant at Medpak Solutions with more than 12 years of experience, has seen this in her practice. She recalled patients who were extremely stressed and not getting enough of the right nutrients. “Their hair began to fall out, or their nails were brittle and broke,” she said.

What Does ‘Enough Food’ Look Like In Practice?

So you need to eat “enough” and get the right nutrients, but what does that entail more specifically?

The number of calories to aim for isn’t clear-cut. “Energy needs vary from person to person, and are based on factors like age, gender and activity level,” Young said.

Even the typical “2,000 calories a day” you hear isn’t true for everyone; in fact, it’s somewhat arbitrary, as it was picked as an easy-to-remember number that fit into self-reported ranges.

But here’s the good news: You don’t need to worry about calorie counts anyway. Young said the key is listening to your body.

“I suggest following your body’s hunger and fullness cues and enjoying a variety of foods from all food groups,” she said. “I recommend working with a non-diet registered dietitian if you’re unsure whether you’re meeting your energy needs or not, or if you need help finding balance in your diet.”

In the case of hair and nail growth, some nutrients will be more directly beneficial than others. The dermatologists and dietitians suggested the following:

• Iron (found in red meat, seafood, poultry, beans and spinach)
• Zinc (found in red meat, poultry and dairy products)
• Biotin, aka vitamin B7 (found in eggs — especially yolks — as well as salmon, sweet potatoes, mushrooms, peanuts and avocados)
• Collagen (found in bone broth and gelatin)
• Healthy fats (such as salmon, tuna, avocados, walnuts, flaxseeds, olive oil and avocado oil)
• Fat-soluble vitamins A, E, D and K (often found in meats and/or green vegetables) that need fat for absorption. You can also get vitamin D from spending time in the sun.

You may notice many of those foods are protein sources, which makes sense, according to Chacon. “There’s a reason protein is having a moment right now,” she said. Essentially, it goes back to Leer’s earlier point: Hair and nails are made of keratin, a structural protein.

Other protein sources she mentioned include legumes, Greek yogurt and Omega-3 fatty acids.

While certain nutrients provide certain benefits for our body, it’s crucial we clarify on this point: “Healthy eating” doesn’t mean eating just “health foods” or restricting. It means eating what’s truly enough (which is more than diet culture would have us believe) and of all food groups (aka, not just proteins and veggies).

Taylor affirmed this from her professional experience. “I work with teens in the clinic regularly who are attempting to eat ‘clean’ or skip meals, and their body indicates that it isn’t enough,” she said.

Leer wouldn’t advise focusing on specific nutrients anyway. “Instead, I would ensure they are receiving proper nutrition holistically for their specific needs,” she said.

Other Ways To Keep Your Nails And Hair Healthy

While food is vital to protecting your hair and nails, it’s not the only thing.

Taylor recommended ensuring good circulation, saying it delivers oxygen and nutrients to your scalp and nail beds. A 10-minute walk, putting your legs on the wall and a red light therapy lamp all help boost circulation.

Leer spoke about stress and how it can impede nail and hair growth. “Stress causes your body to produce more cortisol, which can put hair follicles into the ‘resting’ phase leading to thinning hair,” she explained. “Cortisol can also lead to thin, brittle nails.”

Additionally, pay attention to the habits that stress can lead to. “Don’t overdo styling or picking,” Taylor said.

Along the lines of managing stress, make sure you’re getting enough deep sleep. It supports protein synthesis, Leer said, which is essential to keratin production and therefore hair and nail growth.

Last but not least, don’t forget to stay hydrated. Generally, that means drinking around 0.5 (or more) ounces of water per pound of body weight daily.

“Keeping your body hydrated helps to aid it in doing its thing when it comes to detoxing and cycling hair and nail cell turnover,” Chacon said. “Keeping things moving and flushing the body with clean, fresh water is an incredibly easy and effective way to support your body’s health and processes.”

Ultimately, listening to your body and giving it what it needs — even if its requests surprise you — is crucial. Our bodies were built to function at their best, but they need our help.

“If you notice your hair or nails are different, your body could be sending you a message,” Taylor concluded. “Your body should feel good in your own skin, and that means your hair and nails, too.”