HW vs. CW: Weight Suppression in Bulimia Nervosa – Part I

HW. CW. LW. GW1. GW2. GW3. UGW.

If you have (or have had) an eating disorder (or dieted and used online forums), chances are you know what those acronyms mean. And if you have browsed blogs written by eating disorder sufferers, chances are you have come across these acronyms too. After all, they are a prominent feature of many such blogs.

If you are lost, I’ll fill you in: the acronyms stand for Highest Weight, Current Weight, Lowest Weight, Goal Weight 1/2/3, and Ultimate Goal Weight (UGW). Unsurprisingly, most individuals with eating disorders, much like dieters, like to keep track of their weight loss — that is, the difference between the highest weight, HW, and the current weight, CW.

Researchers call this difference weight suppression (WS, more specifically, the highest adult body weight) and one’s current weight). It can be thought of as the extent to which an individual has reduced their weight through dieting. It is usually calculated based on self-reported highest adult body weights. (So those “stats” might actually come in handy, for research purposes, anyway.)

WEIGHT SUPPRESSION IN BULIMIA NERVOSA

Weight suppression, though not a novel concept, has only relatively recently been studied in relation to eating disorders. In eating disorders, the focus has been on understanding the significance or predictive value — if any — of WS in individuals with bulimia nervosa.

In other words, can the difference between HW and CW inform the patient or the treatment team about anything? For example, can WS be useful in predicting the weight gain that is to be expect (or should be the goal?) during treatment?

There has been some evidence that individuals with BN typically have substantially higher starting weights (before eating disorder onset) than do those with AN (Butryn et al., 2006; Lowe et al., 2006). Lowe et al. (2006) suggest that in the process of developing their disorder, many individuals with BN lose as much weight as those with AN. However, after losing a significant amount of weight, a portion of individuals eventually begin to engage in binge eating and purging behaviours, and a subset of those go on to develop bulimia nervosa.

However, by the time these patients enter treatment, many have regained some or all the weight they have lost. (Keep in mind that BN patients are typically “within their normal weight range”, though, of course, what that means in practical terms can vary.)  But if their starting weight is relatively higher, many of these patients are still below their desirable or healthy weight. In other words, many are still probably weight suppressed. (Even if on the BMI scale they are in the so-called “normal” range.)

One study, by Murphy-Eberenz and colleagues, found that the average degree of WS in a sample of BN patients was over 10 kg, or 22 lbs.

WEIGHT SUPPRESSION: A RISK FACTOR FOR DEVELOPMENT AND MAINTENANCE OF BULIMIA NERVOSA?

Importantly, several studies have identified WS as a potential risk factor for the development and maintenance of BN.

1. Cross-sectional studies have found:

• Positive associations between WS and the frequency of binge-eating and purging in individuals seeking treatment for bulimia spectrum disorders (e.g., Lowe et al., 2007)
• A study by Butryn, Juarascio & Lowe (2011) found that participants (64 women with threshold or subthreshold BN) with higher WS reported more frequent bingeing and purging episodes

Although it is possible that these findings are due to weight fluctuations, in Butryn et al.’s study, as in other studies (e.g., Butryn et al., 2006; Carter et al. 2008) weight fluctuation was not related to binge eating or purging frequency. This suggests that it is the state of weighing less than one’s highest weight that may contribute to the maintenance of bulimic symptoms rather than bulimic symptoms being merely associated with weight fluctuation.

2. Longitudinal research has shown that:

• WS predicts the onset and maintenance of bulimic syndromes (Keel & Heatherton, 2010)
• And that WS predicts a longer time to achieve first full remission from BN (Lowe et al., 2011)

WEIGHT SUPPRESSION AND BULIMIC SYMPTOMS: WHAT’S THE RELATIONSHIP?

There are several possible reasons why weight suppression could contribute to bulimic symptoms.

Firstly, individuals with high weight suppression may suffer from reduced leptin levels (Friedman & Halaas, 1998). Favaro and colleagues (2008) demonstrated decreased leptin concentrations in individuals with BN compared with weight-matched controls. Leptin is an important satiety signal — reduced levels may therefore further increase vulnerability to binge-eating episodes.

Secondly, the Cognitive Behavioural Therapy (CBT) model for BN theorizes that individuals are caught in a psychological bind due to their overemphasis of weight and shape in determining one’s self-evaluation and self-worth. According to the model, this results in extreme weight control behaviours and binge eating, which consequently leads to body dissatisfaction and lowered self-esteem. This forms a vicious feedback loop that reinforces the disordered behaviours. However, by considering weight suppression, we could derive a more nuanced explanation.

In particular, adding to the CBT model, Butryn et al. (2006) have proposed that individuals with BN are caught in a psychobiological bind. Considering that BN patients tend to have higher pre-ED weights than their nonbulimic counterparts and that they are more likely to have one or both parents who are overweight (Fairburn et al., 1997; Garner & Fairburn, 1988), this tendency toward being higher in weight may play a role in initiating or “triggering” (for a lack of a better word) the weight loss in the first place. And significant weight loss and extreme dieting may not only increase risk for developing binge eating behaviours but also for maintaining them (Stice et al., 2008).

IN SUMMARY

To restate, weight suppression has been identified in both cross-sectional and longitudinal studies to be related to BN symptoms. Studies investigating the relationship between WS and weight gain have, too, produced consistent results.

However, studies exploring the relationship between WS and treatment outcome have yielded inconsistent findings. This is an obviously an important question to answer because, for one, varying degrees of weight suppression may necessitate different treatment protocols. For example, it could guide treatment providers in identifying individuals who may need to gain a significant amount of weight and those who may not.

In my next post, I will discuss the relationship between weight suppression and treatment response/outcome in patients with BN.

Editor’s (err, Tetyana’s) Notes. First: SEDs readers, please welcome Jackie! This is Jackie’s first post on the SEDs blog. I came across Jackie’s blog (here) and thought I’d invite her to contribute to the Science of Eating Disorders blog and here we are! Two: I made a lot of changes (mostly additions) to this post, so I’ll take the blame if things no longer make sense. Three: I will probably put up Jackie’s follow-up post tomorrow or the day after. Four: I apologize for the lack of posts recently, I have been busy with work, and random projects, and enjoying the weather, and all this other awesome good stuff — which is important, and while I don’t actually feel guilty for neglecting the blog (I bet you thought I would, eh?), I do hope to find more time for it in the near future — or more contributors!

References

Butryn ML, Lowe MR, Safer DL, & Agras WS (2006). Weight suppression is a robust predictor of outcome in the cognitive-behavioral treatment of bulimia nervosa. Journal of Abnormal Psychology, 115 (1), 62-7 PMID: 16492096

Butryn ML, Juarascio A, & Lowe MR (2011). The relation of weight suppression and BMI to bulimic symptoms. International Journal of Eating Disorders, 44 (7), 612-7 PMID: 21997424

Lowe MR, Davis W, Lucks D, Annunziato R, & Butryn M (2006). Weight suppression predicts weight gain during inpatient treatment of bulimia nervosa. Physiology & Behavior, 87 (3), 487-92 PMID: 16442572

Zunker C, Crosby RD, Mitchell JE, Wonderlich SA, Peterson CB, & Crow SJ (2011). Weight suppression as a predictor variable in treatment trials of bulimia nervosa and binge eating disorder. The International Journal of Eating Disorders, 44 (8), 727-30 PMID: 20957701