Calorie counting and hair loss
Calorie counting and hair loss


Hair is energetically expensive and can be affected by a low-calorie diet that lacks the right nutrients.  Hair growth can also be affected by a diet high in calories but low in nutrients.  When considering balancing calories for healthy hair growth, the nutritional value of the food is the highest importance.  Diets that are based on reducing calorie intake can lead to hair loss conditions such as telogen effluvium.


By definition, a calorie is the quantification of the energy it takes to heat a kilogram of water by 1˚C.  On this basis, the change of temperature of water is meant to tell you about the energy you can extract from specific food.

This study led to food companies not even bothering to submerge their wares in an avatar of water, instead food scientists used Atwater’s measurements to assign average calorie numbers for a gram of fat, a gram of carbohydrates, and a gram of protein.  These numbers gave food companies a number, with no need to waste time burning food.  After these calculations have been made, the burning question is, are these numbers accurate?


Fibre, for many years, has been counted at only 2 calories per gram, but recent studies show that the gut is teeming with bacteria that converts fibre into fat, which then is converted into energy, thus making this zero-calorie food calorific.  Another issue with calorie counting is that whilst we can obtain an indicative value of the energy stored within that food, we have no information about the accessibility of the energy within that food.

Your plate may hold 1,400 calories, but you may not be able to access all of that available energy.  It is easier for the body to digest food that has been broken down or processed.  For example, the body would have to work harder if it wants to break down raw broccoli compared to cooked broccoli. The cooking process breaks down the cellulose walls that wrap each plant cell and breaks down the complex carbohydrates into smaller sugars that are easier for your body to absorb. In most cases, cooking means your body needs to exert less metabolic effort when you digest your food. In other cases, the difference between raw and cooked is the difference between absorbing and not absorbing some of your meal.


One study saw a 50% increase in hair shedding after weight loss [1].  The focus should, instead, be put into eating the right kinds of food to balance endocrine hormones, boost metabolism, and increase hair growth.  Forget calories in, against calories out, and consider the body as a dynamic system that cannot be cheated with this oversimplified method of energy quantification.

Eating low quality food will eventually cause a hormonal and biochemical backlog that will lead to metabolic issues.  The body will stop responding to normal hormonal signals, so eating a low-calorie diet will not be productive.  When you eat whole, unprocessed foods you are essentially eating food that will make you feel full but will never be able to absorb all the calories in the food.  Unlike low calorie and processed foods, whole foods will contain vital nutrients such as iron, zinc and B complex vitamins needed for normal hair growth.  Often, it is the lack of these nutrients that contribute to hair loss.


When several types of nuts were studied by researchers, it was found that people absorbed far fewer calories than was expected [2].  The study looked at metabolised energy (the energy available to the body) and found that the metabolised energy of certain nuts was much lower than anticipated.  Specifically, walnuts were found to have 21% less metabolised energy than indicated by calorie count.

How you prepare your food influences the number of calories you absorb.  Any kind of processing such as: heating, mashing, and blending food influences the calories you absorb.  This means that all unprocessed foods have an overestimated calorie count simply because all the energy in the food is not accessible to the body to turn it into metabolised energy.  This does not consider other contentious issues, such as food interactions, or the differences of gut bacteria colonies that impact uptake of food in the gut.


If we were to calculate the number of calories an individual would need for healthy hair growth, we would have to factor in Basal Metabolic Rate (BMR).  This is often determined by the Harris-Benedict Equation [3].  The equation gives a number that determines how many calories you would burn if you spent the whole day in bed.

Once this number is determined you can therefore determine how many calories you need to maintain a healthy weight, and function at an optimal metabolic rate.  If you are overestimating calories obtained from whole and unprocessed foods, then you can run at a deficit of around 20%.  This means you are eating 1/5 less than your body requires.

If you are eating processed foods that are low in calories (such as zero calorie noodles) then not only are you robbing your body of much needed energy, but you are also eating food devoid of the nutrition (minerals and vitamins) that the hair follicle desperately needs to grow.


To grow healthy hair, and maintain a healthy weight, you should concentrate on:

  • Healthy proteins from good quality meat poultry or pulses and nuts
  • Eating regularly (strictly every 3-4 hours)
  • Eating a portion of protein every morning
  • Eating whole, unprocessed foods

The significant factor, when it comes to food, is the feeling of being full: satiety.  Eating proteins and fat leaves you more satiated than eating carbohydrates because carbohydrates are absorbed quickly, and proteins and fats are harder to digest.  Proteins and fats also trigger the hormones that tell you that you should stop eating, whereas carbohydrates increase sugar levels and stimulates the release of insulin.

Insulin is a big player in the control of intermediary metabolism and has a huge effect on carbohydrate, lipid protein, and mineral metabolism.  An imbalance in insulin signalling has widespread consequences to the many organs and tissues including the hair follicle.  In fact, high levels of insulin have been associated with female pattern hair loss and excess shedding of the hair due to insulin resistance.


Whilst calories are indeed a measure of energy contained within food.  Remember you are a dynamic biological system, and a nutritious diet will promote weight loss, clear skin and healthier, thicker hair.


  1. Alopecia in crash dieters. JAMA. 1976 Jun 14;235(24):2622-3.
  2. Walnuts consumed by healthy adults provide less available energy than predicted by the Atwater factors. The Journal of nutrition. 2016 Jan 1;146(1):9-13.
  3. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. The American journal of clinical nutrition. 1984 Jul 1;40(1):168-82.