Does OMAD Cause Hair Loss?

picture of a lady with long hair

Recently I’ve been asked an interesting question about doing one meal a day and any potential side effects. More precisely about does OMAD cause hair loss?

OMAD does not cause hair loss. However, symptoms like losing hair are related to nutrient deficiency. Nutritional deficiency may impact both hair structure and hair growth. This means, if your diet is low on protein, you may have niacin (Vitamin B3) deficiency that is causing the problem.

Niacin is a vitamin that can be easily manufactured by the body from an amino acid called tryptophan.

However, if you’re doing any caloric restriction diet for a prolonged period of time, and not paying attention to your macronutrients, like proteins, hair loss can be a sign of niacin or other nutrient deficiency.

Why I’m Losing Hair After Weight Loss?

Many times when people want to lose weight, instead of asking for help from the weight loss coach, trainer, or physician, they dive in cold-turkey and then fall into the trap of nutrient deficinecy.

They may get inspired by people who already lost a significant amount of weight. And to get similar results, they blindly follow the same steps, without any preparation.

Before and after pictures can be really inspiring.

They give us this sense of certainty that we are barking on the right tree. And as long as I follow the same steps, I will lose weight, too.

But here is the problem.

Many times those people who lost a significant amount of weight in a short time never really follow any professional advice either. And just because something is “working” on month 6, it doesn’t mean doing the same thing will be good at month 15.

So the hair loss, which is one of the common side effects of extreme weight loss, is not because of one meal a day. It is poor planning, and lack of body knowledge that results in nutrient deficiency.

In other words, they are so invested in the weight loss results so they forget about the basics.

Nutrition is complicated.

And it’s not one size fits all. So it can be very confusing, especially for people who never study nutrition. And because there is so much conflicting information out there, it’s easy to follow advice based on emotion and social proof.

Everyone is doing A, so it means A must be working.
10 people lost 50-pounds doing B, which means I can do B and lose 50-pounds too.
Dr. X said it’s wrong, so I cannot do this.

People who experienced sudden weight loss, and disregarded their macronutrient intake, may struggle with problems like hair loss.

This happens due to the lack of certain vitamins and minerals that keep your hair follicle strong, maintain protein synthesis and ensure cellular proliferation and differentiation is on point.

And if someone is been changing the dietary habits back and forth, doing extreme fasting episodes, and eliminating some staple foods, then we have a problem.

Apart from niacin, there are several more nutrients that can cause hair loss if the body is in the deficiency.

The studies are limited and there is no one magic nutrient that can “cure” the problem. That’s why if you happen to have symptoms, instead of buying supplements, take a look at your diet and consult with your doctor.


Iron deficiency is another common cause of hair loss. However, studies are not clear to what degree iron may contribute to hair loss.

Hair follicle cells are one of the most rapidly proliferating (dividing) cells in the human body. And it seems that iron plays a role in regulating some of the genes in the body that have been identified in the hair follicle. It also plays a role in enzymes for DNA synthesis (source).

People who are at risk of iron deficiency are premenopausal women, vegans, and people who consume a lot of alcohol.  


Alopecia is the medical term used for hair loss. Alopecia is a common complication that can happen after a sudden weight loss. One of the reasons for that can relate to zinc deficiency.

Zinc is an essential mineral that is needed by multiple enzymes and several factors that regulate gene expression. It is also component of many enzymes that regulate protein synthesis and plays a role in pathways that govern hair follicle morphogenesis (source).

Multiple studies showed that people who experience significant hair loss have a lower zinc concentration as compared to healthy controls (source).

The bad news is for vegans and vegetarians who eat only plant-based food because the bioavailability of zinc is lower in vegetables than meat (source). Also, vegans and vegetarians usually eat more legumes that contain phytates, which is zinc absorption inhibitor (source).

Niacin (Vitamin B3)

You can get niacin from several foods. However, because of the changes in the harvesting processes, the majority of grains are stripped from the outer layers (bran and aleurone layer) of the grain.

So during the milling and harvesting a lot of the vitamin goes left of the ground. However, the other way to get niacin is from the amino acid tryptophan that is converted into the vitamin B3 in the liver.

This is part of the protein synthesis.

Then niacin is being converted into NAD (nicotinamade adenine di-nucleotide) that is a chief engineer for over 400 different processes.

So high-protein diets immediately give you the safety net and endure you won’t have any problems.

People who take antibiotics for an extended period of time can have a problem with this process because antibiotics inhibit protein synthesis.

Fatty Acids

Another factor that can cause hair loss is a deficiency of polyunsaturated essential fatty acids.

For instance, lack of linoleic acid (omega-6 fatty acid) and alpha-linolenic acid (omega-3 fatty acid) can result in malabsorption disorders, hair loss from the scalp, from eyebrows, lightening, and thinning the hair (source).


The next nutrient (actually lack of it) that can potentially contribute to hair loss is selenium that plays a role in hair follicle morphogenesis (source).

However, there are no many studies done on humans to confirm that.

And despite the lack of studies, many hair growth supplements contain selenium, which can lead to selenium toxicity that is linked to hair loss (surprise, surprise), blistering skin lesions, GI symptoms, and memory difficulties (source).

Amino Acids and Proteins

Protein malnutrition and deficiency can result in changes like hair thinning and hair loss (source).

Some of the amino acids that can play a role are tryptophan, which is responsible to manufacture vitamin B3, and further into NAD.

An essential amino acid, L-lysine, is responsible for iron and zinc absorption. L-cysteine is a building block of keratin in combination with pantothenic acid.

So as you can see, it’s complicated.

Michal Sieroslawski

Michal is a personal trainer and writer at Millennial Hawk. He holds a MSc in Sports and Exercise Science from the University of Central Lancashire. He is an exercise physiologist who enjoys learning about the latest trends in exercise and sports nutrition. Besides his passion for health and fitness, he loves cycling, exploring new hiking trails, and coaching youth soccer teams on weekends.

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