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Surgery and the redevelopment of eating disorders
According to a presentation at the Digestive Disorders Federation meeting in Liverpool, UK, bariatric surgery procedures could lead to the redevelopment of eating disorders.
In her presentation “Eating Disorders and gastric bypass: slipping back?” Dr Denise Thomas, Head of Nutrition and Dietetic Services, Portsmouth Hospitals NHS Trust, UK, said eating disorders such as anorexia nervosa (AN) and bulimia nervosa (BN) have a psychodynamic formulation.
Bariatric surgery and eating disorders
Figure 1: Disordered eating cycle
Thomas discussed the link between bariatric surgery and eating disorders, and explained how surgery influences predisposing (low-self esteem), precipitating (extreme dieting practice) and perpetuating (the biology of semi-starvation) factors, which could cause their redevelopment.
Previous research has reported both bulimic episodes and vomiting for weight issues occuring after surgery. Binge eating behaviour is also triggered by extreme dieting. However, the self induced vomiting seen in BN is not seen post surgery as vomiting is generally not a purging behaviour and 60% of cases describe vomiting in response to an intolerable food or one that has plugged (the result of overeating particularly bread, pasta and dry meats).
“Bariatric surgery leads to significant changes in eating patterns. The main procedures are all primarily restrictive in nature and as such could be suggested to produce a precipitant to eating disorder pathology,” she added.
According to the literature, one paper has reported that gastric surgery and restraint from food were the triggering factors of eating disorders in morbidly obese patients, however, there have been no recent case reports of AN.
Thomas asked the audience to consider those patients who exceed their target weight loss and appear to be in a downward spiral into normal BMI and beyond. “How many of these are now afraid to eat and complain of gut symptoms? We investigate for many gastro intestinal issues, but are these patients displaying anorectic behaviours?”
Conditions such as anorexia can be triggered by severe dieting restriction, so in a group of patients undergoing an enforced change from overeating to an extreme restricted diet, this dramatic change in eating habits could be a risk factor in this group of patients (as described in the psycho-dynamic formulation).
Chicken or the egg?
The question then emerges of whether the eating disorders are present before surgery or is there a new population post-surgery? A population that is adhering to a reduction in portion sizes, is chewing thoroughly, eating slowly and feels the need to induce vomiting to relieve sensations/pains, these are all permitted behaviours that resemble eating disorder pathology. These conditions therefore “find a home” more readily in some patient’s psyches following surgery.
Binge eating disorder (BED) is the most common eating disorder reported in patients prior to bariatric surgery, ranging from 10%–50% and 27% of patients present with a lifetime history of the disorder.
The Diagnostic and Statistical Manual of Mental Disorders (DSM) defines BED as the consumption of a larger than normal amount of food, taken over a discrete period of time, accompanied by a subjective loss of control. This is followed by an association of guilt, shame, eating rapidly and having physical discomfort when eating.
According to Thomas, it was this definition that caused many surgical teams to deny patients exhibiting BED surgery, as it was felt the overeating would be incompatible with the restrictive nature of the surgery.
However, one study has shown dramatic decreases in binge eating due to the restrictive nature of the procedure, with a reduction from 48% to 0% of the cohort.
For patients with BED, one major issue is the return to eating larger volumes of food often within six months of surgery as this triggers feelings of guilt and shame, and of letting the surgical team down.
“It is easy to see how post-surgery patients may well exhibit some of the traits more commonly seen within BED. Although these patients appear to lose less weight than those who were previously non-binge eaters, weight loss post-surgery results are significant.”
Disordered eating cycle
Understanding the vulnerability of patients is an important aspect of their pre- and post-surgical care. In this respect, Thomas said it is vital to recognise the disordered eating cycle, a continuing sequence of stages patients undergo (Figure 1). Disordered eating cycles, whether bulimic or binge eating, have a pattern based on restriction of eating. Patients focus on the negative (rules too hard, denial of foods), leading the need to over-eat/crave, which triggers the feeling of failure, in turn increasing the negative feelings and the cycle begins again.
“Obese individuals who have been susceptible to this pattern of behaviour are therefore exposed to these issues post-surgery. There is a vulnerability which must be recognised, understood and treated,” explained Thomas.
Types of binge eating
According to Latner and Clyne there are two types of binge eating, objective and subjective. Objective binge eating is the consumption of a large amount of food with a loss of control, whereas subjective binge eating is the consumption of a moderate amount (perceived as larger than normal) with loss of control. This suggests that it is the loss of control that is crucial.
“Subjective binge eating seems to possibly fit the pattern of the bariatric patient post-surgery and it is the loss of control that is clinically significant, rather than the amount of food eaten,” she said. “This resonates with the experience in my practice, where patients compare the volume of food they eat. The patients who perceive that they are eating too much feel guilt and shame, “I have let you down” being a common phrase. They believed that they would never eat this way again and feel distraught, although the “binge” is still considerably less than it was before surgery. They feel 'out of control'".
Thomas then asked whether bariatric surgery triggers a switch from binge eating to a higher proportion of grazing behaviour in these patients.
Grazing is defined by the consumption of a smaller amount of food taken continuously over a longer period of time, eating more than the subjects consider normal. One study in particular examined the relationship between pre-operative and post-operative eating behaviour and weight loss outcome, and found that food volume decreased but extended eating periods increased from 26% to 38% of patients post-surgery.
It appears as though pre-operative binge eaters became grazers, which was associated with poorer weight loss and higher psychological distress, tipping patient back into the negative cycle of disordered eating again.
They concluded that uncontrolled eating (higher energy intake with higher % fat, with less dietary restraint and more hunger) and grazing were identified as two high-risk eating patterns post-surgery.
“Initially there is a great euphoria post RYGB because of the dramatic weight loss and a feeling of being in control for once, but that quickly changes with a return of “appetite” as they perceive it,” said Thomas. “The ability to eat “more” is taken as “I must be hungry, because I am eating and able to eat” independent of the effect of gut hormones.”
Surgery means patients are placed back into the cycle of having to make decisions about volume and choices of foods. This becomes part of the non-core elements of psychopathology of the eating disorder. The pre-occupation with food and rituals that the surgery itself causes, which prior to surgery had been due to needing to exert control, now it has to be considered to ensure that food can be eaten and tolerated.
“Gastric by-pass surgery therefore alters eating behaviour but not the triggers to motivate the patient to binge eat,” she added.
The evidence points to patients having conflicting issues. Their behaviour has a history of binge eating, but following surgery this affects the patient’s eating habits with RYGB reducing circulating ghrelin levels and increasing GLP-1 & PYY. However, for some patients this does not appear to provide a feeling of satisfaction long term and hence they switch into a pattern of grazing behaviour.
Previous binge eaters are more likely to continue with this eating pathology or switch to grazing. The surgical effect on eating behaviour might also trigger a negative effect as it makes individuals who were super sensitive to food choices, thinking about food continually, all the more encouraged to do so.
Thomas said it is the likely interaction with the environment (psychosocial issues, learned behaviour etc) that is the very powerful influence on patients. Those who respond to such triggers may not be aided as much by weight loss surgery, because these psychosocial cues are not altered and remain constant in their lives.
Thomas said that cognitive behaviour therapy before surgery on disordered eating/binge eating appears beneficial and Ashton et al have shown that outcomes post-surgery can improve (46% vs. 38% EBWL at six months; 59% vs. 50% at one year).