But what about patients that are overweight or obese? Often behavioural weight loss is a part of treatment and this may involve a proscribed period of caloric restriction. Dietary restraint theory would predict that binge eating would increase following this intervention. This is certainly a belief held by a number of eating disorder therapists that I talk to.
What does the data say? A recent review was published in Obesity Reviews by da Luz et al (2015) and also reported at the ANZAED 2015 conference. The paper reviewed the impact on Very Low Energy Diets (VLED) or Low Energy Diets (LED) on binge eating. A LED or VLED diet is where you consume between 450 – 1250 calories, which is typically achieved by the use of meal replacement drinks. Importantly, these studies were all done under clinical supervision of the dieting, and this may be different to the dieting of patients with eating disorders. Once weight loss is achieved with the LED, food is gradually brought in to replace the meal drinks (but only up to about 1500 calories). The advantages of these treatment for obesity seems to be reduced appetite, rapid and motivating weight loss leading to health benefits, improvements in fertility and respiratory disorders. Weight loss has been maintained for up to 3 years.
The da Luz paper found 10 papers (out of the original 4150 that came from their initial literature review) that were scientifically robust enough to allow conclusions to be drawn.
So in patients with pre-existing binge eating behaviour or diagnosis of binge eating disorder did a LED or VLED lead to an increase in binge eating. There were 4 studies that addressed this question. In all of these studies significant reductions in binge eating were observed during and after the dietary intervention. In one study the reduction was 56% and abstinence was reached in 33% of participants. In another, at 12 month follow up, 57% of participants no longer made criteria for BED. There was also an indication that remaining binges were smaller in quantity at end of treatment. Overall this seems pretty good data to challenge the thinking that we should not be prescribing diets to overweight or obese binge eating patients. The authors point out that prescribed and monitored diets may be different to the way patients typically diet and this may be important. The structure provided by having your eating and weight monitored by a health professional may be important.
There may be other reasons as to why the decrease in binge eating occurred. Weight loss is associated with increases in mood. If mood is better there is less need for the emotional regulation function of binge eating. LED and VLED plans also appear to reduce appetite that may lead to a decrease in drive to binge.
Before we get too excited and begin prescribing VLED to all patients that are overweight or obese that binge, there is a word of caution. In patients that presented with binge eating, but at a sub clinical level, results were mixed. In this group the majority of studies indicated an improvement in binge eating, at least during the dietary restriction phase of treatment, but in three studies relapse to bingeing occurred when food was being reintroduced.
What if you are overweight or obese but don't have binge eating but want to lose some weight and think a VLED may be helpful. Apparently not. In three studies, participants with no previous binge eating showed an increase in binge eating at the end of treatment. In one study around 10% of patients made criteria for Binge Eating Disorder after the intervention. In another study, 30% of participants reported increased binging at the end of treatment and this increased to 63% a year later (although they did not make criteria for BED). So VLED may lead to an increase in binge eating in individuals who are not binge eating.
Papers like this are always controversial in eating disorder conference. This is I think because when we think eating disorder the field still tends to focus on anorexia primarily, and then bulimia. We shouldn't neglect to include binge eating disorder in our thinking of eating disorders. It is the most common eating disorder and the 'newest'. It is important that, based on data like that presented in the da Luz paper, we can not simply adapt our treatments for BN to BED, we need to prepare for our traditional thinking to be challenged and extended by research specific to BED and obesity.
As always, thoughts are welcome.