Eating Disorder and Metabolism in Narcoleptic Patients

In the recent article, Eating Disorder and Metabolism in Narcoleptic Patients, it was shown that the energy balance of narcoleptic individuals was impaired compared to healthy individuals.

It had been long reported by doctors that their narcoleptic patients tended to be overweight compared to other patients, and that patients tended to have a higher BMI (body mass index) “regardless of whether they were treated with drugs increasing appetite, and regardless of whether they had cataplexy.” More importantly, not only are narcoleptics more overweight than the “healthy” control population, but they are also more overweight than their family members, suggesting that the etiology of obesity and narcolepsy extends beyond a familial predisposition to be a little bit thicker.

In the hypothalamus, hypocretin neurons are found in the region of the brain called the feeding center, and when it was found that narcoleptics have a reduction in hypocretin-producing neurons in the brain, it was then suggested that metabolic functioning may also be impaired.  In the paper reviewed here, the authors set out to determine energy expenditure in more than 500 narcoleptic patients. Some patients had cataplexy, while some did not, but all were not taking any treatments at the time of the study for their narcolepsy.

Overall, they found that:

1) Narcoleptics tended to have a higher median BMI.  That is to say, we narcos are usually fatter.

2) Narcoleptics have lower rest energy expenditure.  This means that, when not moving, we burn calories at a lower basal rate than non-narcoleptics.

3) Typical, but not atypical narcoleptic patients tended to eat less.  In the study, they separated narcoleptics with cataplexy (“typical”) and those without (“atypical”) and found that typical patients ate less than “healthy controls.”  While there was no food intake difference between typical and atypical narcoleptics, overweight narcoleptic patients ate 1/2 as much as narcoleptic patients with a healthy weight.

4) Narcoleptic patients demonstrate a higher rate of eating disorders, particularly bulemia. Narcoleptic patients tended to demonstrate impaired eating behaviors, including the use of binge eating to control daytime sleepiness. There was no difference between typical and atypical narcoleptic patients, and they found that 1/2 of narcoleptic patients suffered from a mild form of eating disorder.

Narcos are fat.

No offense, but we narcoleptics are fat [1].  In fact, of all of the narcoleptics I have met, I have only met two people (both young men, mind you) that were even remotely in shape.  For me, the fact of obesity and narcolepsy is one of the most unfair aspects of the disease. In the first place, people who don’t know anything about narcolepsy, assume that we are lazy. “Just make your bed and sleep less!” seems to be their cure-all answer.

Indeed, the official stance of The Standford Center for Sleep Sciences and Medicine (home to the famous Dr. Mignot) appears to be: “Many patients with narcolepsy also gain weight as the result of inactivity and sleepiness.”

For years, narcoleptics have fought a huge social stigma that we are somehow lazy sloths that just want to sleep and eat all day, despite the facts that we actually sleep less efficiently than other people, and still gain weight on diets that work for other people!   

Fortunately for us, there is a body of research linking metabolic dysfunction and narcolepsy.  The excitement about these advances (for me, at least) is overwhelming, and there are several reviews on the site summarizing them.

Recently, it was shown that we narcos don’t produce a lot (if any) hypocretin.

hypocretin A

Structure of hypocretin

Our brains are simply deficient in the production hypocretin (also called orexin), and it is hypothesized, though not proven, that we may have a complete loss in the neurons of the hypothalamus responsible for producing hypocretin.  For everyone, hypocretin controls arousal, wakefulness and appetite. A deficiency in hypocretin impairs sleep as well as metabolism, and in addition to being sleepy, narcoleptics have a lower basal metabolism than other people. Because of this, narcoleptics tend to gain weight in spite of eating fewer overall calories than most people. 

Orexin is not only active in the central nervous system, but it has wide ranging action throughout the periphery.  Indeed, mice that lack orexin gain weight as a result of brown fat hypoactivity and reduced energy expenditure. Remember, brown fat is good fat. White fat is the “bad fat” that makes you appear fat.

So what does this mean? Surely, it doesn’t mean that we are now allowed to sleep and eat as much as we want. But it does mean that WE ARE NOT JUST LAZY!  For me, the problem of metabolism and narcolepsy (in addition to the metabolic problems that stem from my hypothyroidism), is an ongoing battle. On the one hand, I am able to harness the power of diet and nutrition to help control my symptoms, but on the other, I am always fighting. Even when I exercise, I can’t eat more than 1,000 – 1,200 calories a day without gaining weight (very quickly, I might add)!

It is clear that narcolepsy is more than just a disease of sleepiness. It is a disease with many faces, encompassing tiredness as well as impaired metabolic homeostasis. In fact, it was recently reported that obese individuals had lower circulating levels of orexin A. The results from the study indicate orexin doesn’t only work in your brain, but that the receptors for orexin (specifically in the gut and pancreas) contribute to systemic effects of orexin itself, and that a deficiency in orexin not only can have neurological effects, but systemic ones as well.