Hypermetabolism in Anorexia Nervosa

Weight restoration is a crucial component of anorexia nervosa treatment. It is a challenging process for a multitude of reasons. Adding to the complexity and the challenge is the fact that during weight restoration, individuals with anorexia nervosa tend to require increasingly more calories to maintain the same rate of weight gain.

That is, individuals need to continually increase their caloric intake, in steps, sometimes upwards of 100 calories (technically, kilocalories) per kilogram per day, to continue gaining weight. For instance, an individual weighing 45 kg may need to eat 4,500+ calories to continue gaining 1-1.5kg (2.2-3.3lbs) a week. Indeed, studies have found that standard resting energy expenditure (REE) equations tend to overestimate caloric needs at the beginning of refeeding but underestimate them in the later stages (Forman-Hoffmann et al. 2006; Krahn et al., 1993).

After achieving a healthy weight, individuals recovering from anorexia nervosa still typically … Continue reading →

Energy Expenditure in Anorexia Nervosa Patients

How many calories do patients with anorexia nervosa need to eat to gain a kilo (2.2 lbs)? It seems like a simple question and one that we should have figured out a long time ago, given the importance (err, necessity) of refeeding and weight restoration in recovery from anorexia nervosa.

Unfortunately, research in this area has often led to contradictory results (see Salisbury et al., 1995 and de Zwaan et al., 2002 for reviews). Fortunately, a paper by Stephan Zipfel and colleagues (2013, freely available here) sheds light on one potential cause of the discrepancies.

But first, some definitions:

TDEE stands for total daily energy expenditure. TDEE has three components: resting energy expenditure (REE), dietary-induced thermogenesis (DIT), and activity-induced thermogenesis (AIT). The gold standard for measuring TDEE is through something called the doubly labelled water technique. REE is usually measured through indirect calorimetry. (These techniques were used … Continue reading →

Avoiding Refeeding Syndrome in Anorexia Nervosa

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 →