2011

Your Body’s Response to Chewing and Spitting: The Role of Insulin

Shelly 19 Comments

In my previous post, I looked at two hormones released during the cephalic phase (gastric secretion that occurs before food is eaten), ghrelin and obestatin, and how they may contribute to runaway eating behavior. Today I’m going to be looking at insulin release during chew and spit (CHSP), a fairly common symptom in eating disorders where the food is tasted, chewed and spit out. Insulin is a small peptide hormone that acts as a key regulator of metabolism; deregulation of insulin signalling plays a role in illnesses such as diabetes and metabolic syndrome. Some people have theorized that CHSP behavior may influence insulin regulation. In fact, there are a number of individuals stating on internet forums that chronic CHSP could lead to insulin resistance, potentially promoting diabetes. As interesting as these theories are, recent data have shown that they are probably not true.

INSULIN RELEASE DURING THE CEPHALIC … Continue reading →

Demystifying the Genetics of Eating Disorders – Part II

Tetyana

In my last post I talked about some methods that scientists use to study the genetics of eating disorders. I focused on a subfield of genetics called behavioural genetics (which you can think of as a field that attempts to understand, in part, the interplay of genetics and environment in behaviour). In this post I’ll shift gears and focus on molecular genetics. I’ll be working of the same review paper by Drs. Zerwas and Bulik (2011). Molecular geneticists study the structure and function of genes on a molecular level. For example, they try to understand how different mutations or alterations in the genetic code can affect protein function and lead to disease states.

GENETIC ASSOCIATION STUDIES

Genetic association studies are hypothesis driven. This means that researchers make a list of genes that are known to be involved in biological mechanisms or behaviours that are affected in eating disorders, such … Continue reading →

Demystifying the Genetics of Eating Disorders – Part I

Tetyana 9 Comments

Today I thought I’d take the time to do an overview of what researchers know about the genetics of eating disorders and try to clear up some common misconceptions. The bulk of the content in this blog post comes from a very nice review paper published in 2011 by Drs. Stephanie Zerwas and Cynthia Bulik on the genetics and epigenetics of eating disorders. In an effort to keep blog posts short, this will be a multi-part mini-series.

When it comes to the genetics of eating disorders, there are two main questions that research ask: What is the relative contribution of genetic factors to eating disorder behaviours? And what are those genetic factors? I’ll talk about research attempting to answer the first question in this post and the second question in my next post.

In order to understand the role that genetics plays in influencing eating disorder behaviours, researchers use family, … Continue reading →

Avoiding Refeeding Syndrome in Anorexia Nervosa

Tetyana 25 Comments

Refeeding syndrome (RS) is a rare but potentially fatal condition that can occur during refeeding of severely malnourished individuals (such as anorexia nervosa patients). After prolonged starvation, the body begins to use  fat and protein to produce energy because there are not enough carbohydrates. Upon refeeding, there’s a surge of insulin (because of the ingested carbohydrates) and a sudden shift from fat to carbohydrate metabolism. This sudden shift can lead to a whole set of problems that characterize the refeeding syndrome.

For example, one of the key features of RS is hypophosphotemia: abnormally low levels of phosphate in the blood. This occurs primarily because the insulin surge during food ingestion leads to a cellular uptake of phosphate. Phosphate is a very important molecule and its dysregulation affects almost every system in the body and can lead to “rhabdomyolysis, leucocyte dysfunction, respiratory failure, cardiac failure, hypotension, arrhythmias, seizures, coma, and … Continue reading →

Medical Complications of Purging in Bulimia Nervosa

Tetyana 1 Comment

Eating disorders are mental disorders with physical complications. Sometimes lots of them. I’ve blogged before about medical complications that are likely to come up in an emergency room setting, but that was a while ago. So I thought today I’d focus specifically on medical complications  that occur in bulimia nervosa (BN) as a result of purging (self-induced vomiting, laxative abuse, and diuretic abuse).

These complications are particularly important because patients with BN often appear healthy and can thus more easily hide their disorder, meaning that treatment is often initiated many years after disorder onset, and the duration of BN is often long, with recovery rates far lower than they should be (in one study, the 5-year recovery rate was a little more than 50%), which means that these complications can persist for many years.

I’ll go through some of the complications of self-induced vomiting, laxative abuse, diuretic abuse, … Continue reading →

Pregnancy, Motherhood, and Eating Disorders: Women's Experiences

Tetyana 7 Comments

There is a common misconception that eating disorders somehow disappear during pregnancy; that becoming a mother stops all those silly worries about being slim and attractive. This is not necessarily the case, and unfortunately, there is a lot of stigma associated with talking about disordered eating behaviours during pregnancy. Openly admitting to it is an invitation, it seems, to being called selfish and vain. The implication is that eating disorders are something only young girls struggle with, and that pregnancy and motherhood are such big and important things that they should be enough to overcome an eating disorder.

Over recent decades, eating disorders have entered the public’s consciousness. They are regularly discussed, and often trivialized, in the popular media, depicted as no more than dieting gone wrong or overzealous weight loss. Yet these conditions warrant serious consideration because they are potentially life-threatening and can persist for years, ruining individuals’ long-term

… Continue reading →

Dopamine and Anorexia Nervosa: Tackling the Myths – Part I (Intro)

Tetyana 4 Comments

There is this prevalent myth on Tumblr eating disorder blogs that increased dopamine (DA) receptor activity or increased DA signalling causes anorexia nervosa. It has left me quite perplexed, as I have never come across a single paper that has shown increased DA activity causes anorexia nervosa. My research for this post also left me empty-handed. I have no idea where this myth comes from, but I thought I’d blog about what research on DA activity in anorexia has shown. This topic will take me a few (not necessarily successive) posts to cover. This first post is a very brief introduction to DA signalling.

First, what is dopamine?

DA is a neurotransmitter–a molecule that one neuron releases to another in order to send a signal. Dopamine is released from one cell (the presynaptic neuron) and binds to its receptors on the other (postsynaptic) neuron. There are five different DA receptors … Continue reading →

Self-Harm is Common Among Adolescents With Eating Disorders

Tetyana 6 Comments

Self-harm or non-suicidal self-injury (SI) are common among adolescents, particularly among adolescents with eating disorders. Previous studies have shown that SI seems to be associated with sexual trauma, mood disorders, and substance abuse. The present study aimed to find out whether (1) SI is associated with any specific eating disorder symptoms, such as bingeing, or purging, and (2) how often clinicians screen for SI behaviours (and whether particular patients are more likely to be screened than others).

Dr. Rebecka Peebles and colleagues looked retrospectively at intake evaluations of 1,432 patients between the ages of 10-21 (mean age 15). Three quarters of the patients were Caucasian, and slightly over 9% were male.  Sixty-three percent had an intake diagnosis of eating disorder not otherwise specified (EDNOS).

MAIN FINDINGS FOR AIM 1

  • Of those screened for SI behaviours, 40.8% engaged in SI
  • Cutting was the most common SI behaviour reported (85%)
  • Bingeing/purging was
… Continue reading →

Anorexia Nervosa: Can We Blame The Season Of Birth?

Tetyana

You might have heard that individuals born between the months of June – August (or sometimes March – August) have a higher chance of developing anorexia nervosa. But is it true? A lot of studies have been done to investigate the question of whether a season of birth (or a month) correlates with a higher risk of anorexia or bulimia nervosa. The results are inconsistent, weak, and fraught with methodological problems.

But first, how could seasons (or the average temperature during birth, or conception) have an effect on the etiology of eating disorders? What’s the hypothesis?

There seem to be two main ideas (summarized in Winje et al., 2012):

  1. alterations in neuropsychological function as a result of sunlight exposure during gestation or postpartum, maternal infections during pregnancy, or nutritional changes (seasonal variation in nutrients, vitamins)
  2. alterations in fertility/reproductive patterns of the parents due to cultural influences, disordered eating in the
… Continue reading →

Diabulimia: Disordered Eating in Type 1 Diabetic Patients

Tetyana 15 Comments

Type 1 diabetes mellitus (DMT1) is a lifelong chronic disorder that occurs when the body is unable to produce enough insulin – a hormone that is required for carbohydrate metabolism. Patients must learn to manage their disorder by monitoring their blood sugar levels on a regular basis, carefully selecting the foods they eat and how much exercise they do. Before insulin was extracted and purified (at University of Toronto!), type 1 diabetes, which usually occurs in children and adolescents, would very quickly lead to death – the body, unable to take in the very thing it needs to survive.

Unfortunately,  patients with type 1 diabetes are at increased risk of developing eating disorders or disordered eating behaviours. Diabulimia refers to an eating disorder in patients with DMT1 who reduce or skip insulin doses to reduce their weight.

The exact prevalence rates vary study by study, depending on the population sample, … Continue reading →