student profile: Mr Phillip Aouad


Thesis work

Thesis title: Chew and Spit (CHSP): Physical, social and physiological impacts of a complex eating disordered behaviour

Supervisors: Kristin STEDAL, Stephen TOUYZ , Nerissa SOH , Phillipa HAY

Thesis abstract:

The DSM-V is used to categorize eating disorder (ED) symptoms into diagnoses that are then used to refer sufferers for treatment. The most widely recognized diagnoses are Anorexia Nervosa (AN), which is typically associated with the behaviour of extreme calorie restriction, and Bulimia Nervosa (BN) and its attendant behaviour of binging and purging (BP). However, the less recognized symptom of chew and spit (CHSP) has been identified in both sufferers of AN and BN (and associated subtypes), as well as other diagnoses such as Other Specified Feeding or Eating Disorder (OSFED).

CHSP is the pathological behaviour of chewing an enjoyable, often calorie dense and high starch food then spitting it out before swallowing it (Mitchell, Pyle, Hatsukami, & Eckert, 1988). Regardless of the patients diagnosis, the premise of an ED is weight control, typically intended to alter the physiology of the sufferer, and CHSP is one method being employed by eating disordered individuals.

Beyond those who suffer from EDs, other individuals may also engage in CHSP for a variety of reasons. Bariatric patients and diabetics, for example, may use CHSP to ‘taste’ food while adhering to their medically-necessary meal plans or eating requirements (James E Mitchell & De Zwaan, 2012; James Edward Mitchell & Zwaan, 2005; Still, Sarwer, & Blankenship, 2014). This is most notably used by Roux-en-Y Bypass (RNY) patients who are unable to tolerate high amounts of sugar or fat, leading to dumping syndrome, where the contents of the stomach gets ‘dumped’ into the small intestine without having time to properly digest in the stomach, causing discomfort and adverse effects (Brethauer, Schauer, & Schirmer, 2015; Johns Hopkins Medicine, 2015; J.E. Mitchell & de Zwaan, 2007). Many bariatric patients (post-op) and candidates (pre-op), are said to suffer from ED symptoms, with the belief that many instances of bulimia and binge eating disorder are especially significantly under reported and undiagnosed during the patient screening process. One of the primary ED symptoms noted post-op is CHSP (Conceição et al., 2013).

The body’s process of preparing to receive food, called the cephalic response, is linked to actual physiological changes in the body. Some studies have focused on specific parts of the physiological impacts, such as on insulin, obestatin, and ghrelin hormones as part of the cephalic response (Broberg & Bernstein, 1989; Guarda et al., 2004; Méquinion et al., 2013; Monteleone, Serritella, Martiadis, & Maj, 2008; Moyer, Rodin, & Cummings, 1993; Teff, 2011; Teff & Engelman, 1996). However, studies on the behaviour of CHSP are still very limited, and CHSP appears to vary in style and severity (ranging from occasional CHSP users to chronic CHSP bingers) amongst sufferers. Developing an understanding of the etiology, psychological impacts, and physiological outcomes of CHSP offers great insight into EDs and disordered individuals. Answering three related questions could lead to enormous insight into EDs and treatment for sufferers:

RQ1) How is chronic, frequent, and/or infrequent CHSP behaviour associated with weight change in ED sufferers?
RQ2) How many calories are ingested during CHSP? Are certain behaviours, such as rinsing the mouth between bites, associated with a decrease in calorie ingestion?
RQ3) What physiological changes or adverse effects are associated with CHSP behaviour after short-term, medium-term, or long-term exposure? How might understanding these help foster awareness and support?

Answering these questions may bring relief and insight for those who engage in CHSP, such as individuals with EDs, diabetes, or are prone to bariatric dumping. Additionally, it may aid clinicians who seek to help these individuals overcome the behaviour of CHSP and ultimately assisting the patient in reducing physical harm to themselves. Some of these effects include weight gain due to accidentally ingested calories, psychological and emotional harm, other physiological impacts (such as damage to teeth, stomach ulcers, and hormonal imbalances), and social impacts (for example navigating socially while caught up in this ED behaviour).

If CHSP is found to have less damaging effects than binging and purging (BP), this may assist bulimics seeking to reduce frequency and severity of purges while transitioning through the steps of treatment for their eating disorder (ED). Furthermore, understanding the health effects of CHSP may help those who engage in this behaviour lessen adverse effects on their own health by taking precautionary or curative measures when engaging in CHSP behaviour

Selected publications

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  • Aouad, P., Hay, P., Soh, N., Touyz, S. (2016). Chew and Spit (CHSP): a systematic review. Journal of Eating Disorders, 4(1), 1-10. [More Information]


  • Aouad, P., Hay, P., Soh, N., Touyz, S. (2016). Chew and Spit (CHSP): a systematic review. Journal of Eating Disorders, 4(1), 1-10. [More Information]

Note: This profile is for a student at the University of Sydney. Views presented here are not necessarily those of the University.