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Understanding Hypermetabolism In Anorexia

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Hypermetabolism in anorexia occurs when the body requires extremely high quantities of food  to meet nutrient needs during weight restoration.

Hypermetabolism can be a complicated and potentially dangerous side effect of eating disorder recovery.

Someone struggling with anorexia nervosa who experiences hypermetabolism will be required to: 

  • Eat more food
  • Consume more fear foods
  • Reduce physical activity 

These are all things that can seem extremely scary for someone with an eating disorder. Hypermetabolism can require 2-5x the usual caloric requirement we would need to see to restore weight. 

Let’s walk through why hypermetabolism might occur. We’ll dive into the treatment to expect if you have hypermetabolism in anorexia recovery, and how this might alter your meal plan. 

What Does Hypermetabolic Mean In Medical Terms? 

Hypermetabolism is when our metabolism is working faster than usual. In other words an increased need for calories in the body. 

Hypermetabolism is seen in many medical conditions including 

In most cases, hypermetabolism occurs when there’s an injury or trauma to the body.  This makes sense as more energy is required for healing. 

However, it is puzzling in the case of anorexia nervosa as metabolism slows during anorexia to preserve basic life functions.  Thus it would be presumed that adding calories would result in weight gain occurring easily. This is not always the case. 

What Causes hypermetabolism after anorexia? 

Hypermetabolism during anorexia recovery is still somewhat of a mystery in the medical world.  

There are structural changes in the brain that occur when someone has anorexia nervosa.  

For example, we see a reduction in: 

  • Gray matter volume in the brain 
  • White matter volume in the brain 
  • Corticol thickness
  • Subcorticol volumes

As the body attempts to survive, the brain goes into a “cave man like” state, preserving only the most vital functions of the brain. 

One hypothesis is that as food is reintroduced, the caveman-like brain kicks into overdrive to use the energy for the starving body. 

This is especially true during the first two weeks of weight restoration from anorexia.  The body is likely using the energy faster than you might feel like you can put it into your body. 

Other theories behind why hypermetabolism might occur during weight restoration include: 

  • Increased thermic effect of food (the amount of energy it takes for your body to digest certain foods)
  • Increased body temperature at night (resulting in night sweats)
  • Low levels of long chain n-3 fatty acids result in increased pro-inflammatory responses
  • Breaking down muscle for energy can cause metabolic shifts 

It is likely that it is a combination of these multiple factors leading to the extremely high metabolism seen following an eating disorder. 

What Are Signs Of Hypermetabolism? 

Common symptoms to look for in hypermetabolism during eating disorder recovery include

  • Weight loss 
  • Low blood pressure 
  • Tachycardia or bradycardia 
  •  Decreased bone mineral density 
  • Hair loss
  • Lanugo 
  • Decreased bone mineral density 

Hypermetabolism can result in weight loss even if you are diligently following an eating disorder recovery meal plan prescribed by your haes dietitian that would normally meet the needs for steady weight restoration. 

What Is Hypermetabolism In Anorexia A Problem?  

Someone recovering from anorexia is already facing MANY challenges when it comes to weight restoration.  Some of these challenges include: 

Emotionally, someone with anorexia is likely experiencing intense fear at the table and a loud eating disorder voice. 

When someone with an eating disorder is meeting the  meal plan given to them and not having the weight restoration intended, this can be extremely traumatic. 

It might the person feel like they have done something wrong, or that they are failing at recovery. 

To be told that what they are doing is not resulting in weight restoration and they now have to eat even MORE food will likely result in extreme distress for the person with an eating disorder. 

All of the physical symptoms that go along with eating more food, including feeling guilty after eating will likely increase as well as a result of the volume of food the person will be required to eat.  

If you are offering meal support for someone with an eating disorder, it is critical that the emotional and physical symptoms that go along with increasing food intake be validated. 

How is Hypermetabolism Treated? 

Hypermetabolism may last through the duration of weight restoration and up to six months post weight restoration. 

Treatment for hypermetabolism in eating disorder recovery will include a treatment team that consists of a dietitian, primary care physician, and mental health counselor. 

Treatment for hypermetabolism often includes: 

  • Increased energy intake 
  • Discontinuing any physical activity 
  • Vitamin and mineral supplementation (multi vitamin, zinc and magnesium are common supplements taken)
  • Incorporating stress management techniques

Typically someone with hypermetabolism will need anywhere from 3-5x (3000-7000 additional calories) to a persons resting energy expenditure (REE)

There has been some evidence that fish oil may be helpful in reducing metabolic rate in hypermetabolism. 

The graph below illustrates the calorie requirements typically needed in weight restoration, and what someone might need if experiencing hypermetabolism. Some people may need even more calories than what is outlined here.

If you are following a vegan eating disorder recovery meal plan, it may be very difficult to meet the caloric needs of hypermetabolism. Considering adding animal products for the duration of weight restoration may be critical.

Hypermetabolism in eating disorders calorie graph

Meal and Snack Ideas For Hypermetabolism in Anorexia Recovery

The volume of food that someone will require if they are experiencing hypermetabolism can feel overwhelming.  

Food that will help to increase overall energy intake without increasing volume of food drastically include: 

  • Peanut butter or other nut butters
  • Hummus
  • Avocado
  • Cheeses
  • Sauces and gravies
  • Double milk (adding evaporated milk to milk-based items such as smoothies and sauces)
  • Oils (avocado, coconut)
  • Hemp seeds
  • Full-fat dairy products
  • Nuts and seeds 
  • Butter
  • Boost or meal replacement shakes
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Hypermetabolism In Anorexia FAQ

What Is Hypermetabolism in Anorexia?

Hypermetabolism in anorexia occurs when the body requires extremely high quantities of food to meet nutrient needs during weight restoration.

What Are Some Foods That Can Help You Meet Hypermetabolism Needs In Anorexia

avocado, nut butters, full-fat dairy, sauces, and gravy, cheese

What Causes Hypermetabolism In Anorexia?

The exact cause of hypermetabolism in anorexia is unknown, but research shows it may be related to structural changes in the brain, changes in the thermic effect of food, low levels of long-chain fatty acids

What is the Treatment For Hypermertabolism in Anorexia

Increasing calories by 3000-5000 kcal above REE needs and reducing physical activity levels

Shena Jaramillo. Registered Dietitian

Hi I'm Shena. I'm an eating disorders dietitian in Washington state. I hold bachelors degrees nutrition & dietetics, cultural anthropology & psychology. I believe in honoring your hunger, having your cake whenever you want it, and that critically analyzing diet culture can change the world!