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Eating Disorder Behaviors, Evaluated Through Science

According to the American Psychiatric Association, eating disorders are mental illnesses marked by severe disturbances in eating behaviors and related thoughts and emotions. The two most common examples of eating disorders include anorexia nervosa and bulimia nervosa, however because these disorders exist on a spectrum in severity and symptomatology, many other patterns of eating can also be classified as “disordered.” Several signs and behaviors indicative or a result of an eating disorder include severe caloric restriction, overexercising, purging (vomiting, laxative abuse, diuretics), binging, among other physiologically damaging behaviors.

Continue reading to learn the science behind why these behaviors might not only be ineffective in managing weight in the long-run, but hold detrimental consequences in health.

Disclaimer: this article does not state that refraining from engaging in these behaviors as a coping mechanism to stressors is an easy transition. Rather, by understanding the physiology behind engaging in these behaviors, we hope to encourage individuals to make more health conscious decisions in their journey of recovery. We recognize that eating disorders are not simply “about the food,” but the underlying psychological distress that manifests in food and body image concerns.


Restricting caloric intake as a mode of behavioral modification in weight management has proven to have little long-term success with a 80% failure rate (Wing and Phelan, 2005). To some, dieting may be necessary because of an intolerance (like celiac disease) or an ethical concern (vegetarian and vegan diets). However, considered a potential aspect or byproduct of a diet, intentionally trying to lose weight through severely restricting the number of calories consumed constitutes as restricting (or restrictive behavior).

What’s scary is that consuming 1,500 calories and exercising for an hour everyday is considered protocol for studies of starvation to observe the effects of severe caloric restriction on the body but is considered a standard weight-loss diet (Aamodt, 2016).

Countless factors account for the lack of success with restrictive diets, including biological factors, environmental factors, and behavioral processes, and instead favor weight regain.

When you restrict calories, your metabolism compensates

The calories in = calories out model cited by diet culture is overly simplistic. Research has identified three major components of the metabolism (or our total daily energy expenditure) including, resting metabolic rate (calories burned when not moving), thermic effect of physical activity (voluntary and involuntary), and thermic effect of food (digesting) (Greenway, 2014).

Maintenance of a reduced body weight is associated with physiological compensatory changes in energy expenditure, which favor weight regain. Adaptive thermogenesis is a biological process that occurs during prolonged energy restriction, and has been widely studied and supported in scientific literature over the past decade. When restricting calories, your total daily energy expenditure (TDEE) is lowered more than predicted because our bodies become more metabolically efficient. With a lower weight, the body has less metabolically active tissue, or fat and tissue. The thermic effect of physical activity is lowered because the energy required to move a body that is of a lower weight is less. With weight loss, there is also a lower biological drive to move or engage in physical activity. The thermic effect of feeding is lowered because when you eat less, your body digests less, and less energy is required to metabolize the food you eat (Greenway, 2014).

So what?

Well when you finally eat more than your diet allows for, you will gain weight because your metabolism is slower. Deliberate attempts to become thinner strongly predict weight gain over the long term, even when researchers take initial weight, diet, and exercise habits into account (Aamodt, 2016).

Caloric restriction promotes binge eating

The restriction experience produces changes in the brain’s stress neurocircuitry, leading to an increased stress sensitivity and the tendency to over-consume high-fat food (Pankevich, 2010).

Diets are inherently stressful (Aamodt, 2016). Stress activates the hypothalamic-pituitary-adrenal (HPA) stress axis and release of stress hormone corticotropin-releasing factor (CRF). As stress and CRF are known to trigger the consumption of calorically dense foods, the reprogramming of stress circuitry may result from repeated dieting, or the yo-yo dieting effect, causing an increased risk for greater weight gain and later obesity through overconsumption (Epel et al., 2001). Research even shows that food deprivation even affects our visual acuity to images of food, meaning food captures our attention more when we’ve gone too long without food. When deprived from food for a period of just 4 hours, Velazquez-Martinez and researchers found a significant difference in the differential attention to food images, with a preference for calorically dense foods (2013). This suggests that our attentional biases can be modulated by food deprivation, making the continual restriction of food that much more difficult.

Purging: Throwing up

Purging by throwing up is common among individuals with eating disorders, and can be triggered by binges, fears of gaining weight, stomach pains, or discomfort with feeling full (Mehler, 2016). According to the International Journal of Eating Disorders, “self-induced vomiting, laxative abuse, and diuretic abuse are the most common methods of purging used in those with disordered eating and eating disorders” (Forney, 2016). The efficacy of “removing excess calories” from the body through purging is debatable, and the general consensus among health practitioners is that purging is not an effective means in managing body weight overtime. However, the prevalence of self- induced vomiting behaviors in eating disorder patients has ranged from 56.6% to a staggering 86.4%, and is the most frequently used purging behavior used by individuals struggling with anorexia nervosa binge/purge subtype, bulimia nervosa, and purging disorder (Forner, 2016).

Intentionally purging one or numerous times a day to alleviate the discomfort of eating or driven by the fallacy of weight management is marked with significant health complications. According to Eating Disorder Hope, up to 49% of individuals with severe symptomatology of bulimia have imbalances such as sodium and potassium. Electrolyte imbalance is caused by dehydration, or loss of bodily fluids, and the loss of potassium and sodium from the body through purging behaviors (Mehler, 2016). Prolonged and chronic dehydration can cause potentially fatal electrolyte imbalances, minimized blood flow throughout the body, muscle cramping, a racing heart, and fainting (Mehler, 2016). Electrolytes are minerals found in the body that are required for organ functioning, and the heart is especially sensitive to potassium levels, and various cardiac arrhythmias may develop when potassium levels are too low, many of which can be fatal (Mehler, 2016).

Regularly exposing strong stomach acids to the enamel of teeth can produce tooth decay, and even break down the gums and tooth overtime, leading to cavities and tooth sensitivity (Forner, 2016). Surprisingly, tooth brushing immediately after vomiting is associated with dental erosion, which is “concerning as approximately one-third of individuals with eating disorders report brushing their teeth after vomiting” (Forner 2016).

Frequent purging may also cause issues throughout the digestive system, including pain and acid reflux. The repeated exposure of the esophagus to stomach acid through purging causes irritation and/or damage to the mucosal wall lining, causing frequent retrosternal burning (heartburn) and even acid regurgitation.

It is unclear how many calories are retained in the gastrointestinal tract after purging, and the efficacy of purging to maintain weight is questionable (Kaye, 2015). Science has shown that there are notable individual differences in the amount and makeup of calories absorbed in the gut, so while purging might seemingly work for one individual, it is strongly the case that those effects are not generalizable (Forner, 2016). Moreover, the speed in which one’s stomach empties varies per individual (such as 45 minutes or 1.5 hours), so purging after this period of time may be difficult for some while easier for others. A 2015 study of 17 participants found a seemingly ceiling on the number of calories retained after a binge when participants consumed more than 2,600 kcal and when they consumed fewer than 2,100 kcal (Kaye, 2015). This means that regardless of whether participants binged on 2,600kcal or 2,100 kcal, the calories expelled through purging had an upward limit. Though a small participant pool, Kaye and colleagues were the first official laboratory study to examine how many calories bulimic patients retain and digest after a binge and vomit (Kaye, 2015).

So, does this method work for managing weight?

Methodologically, most of the available literature about the medical complications and efficacy of purging comes from case studies, and thus causality cannot necessarily be inferred (Forner, 2016). Purging results in an extensive amount of water loss, and the appearance of weight loss shortly after purging may give off the impression that self-induced vomiting works in weight management. However, research participants have repeatedly shown to return back to a higher weight once fluids are normalized and eating is continued (Forner, 2016).


How much endurance training is excessive and damaging to one’s physical and physiological health? Overexercising can be defined as a psychological dysfunction in which obsessive and compulsive exercise is a means of coping with life’s stressors or other psychological problems, such as is the case of many individuals struggling with an eating disorder or disordered eating. Hyperactivity is prevalent in 31% to 80% of individuals with anorexia nervosa, depending on the specific type of anorexia nervosa (purging type vs. restricting type) (Guzman-Grass, 2016).

Although most believe that participation in high levels of physical activity is good for heart health, there is evolving evidence that a high level of excessive endurance exercise may be associated with risk of cardiotoxicity (Levie, 2015). Surprisingly, very high doses of exercise may be associated with increased risk of atrial fibrillation, coronary artery disease, and malignant ventricular arrhythmias. Higher resting heart rates, dips or spikes in blood pressure, dehydration, elevated body temperature, chest pain, irregular bowels and stomach aches, hampered breathing, changes in metabolism, and weight loss are among the key signs of overtraining (Schreiber, 2013). If left untreated, these physical symptoms can interfere with the bodies immune response, chronically elevate the central nervous system’s level of stress hormones, and induce anemia (a fatiguing reduction in the number of red blood cells coursing through the bloodstream) (Schreiber, 2013). In extreme cases, these acute bouts of excessive exercise may lead to cardiac dilatation, cardiac dysfunction, and release of troponin and brain natriuretic peptide (Lavie, 2015).

Joints and muscles are the first physical victims of overexercise, with sprains, muscle tears, and strains occurring at a higher rate among those who don’t how when to quit at the gym (Schreiber, 2013). The risk of fractures, osteoporosis, lower than average bone mineral density (osteopenia), and breaks is increased when addicts refuse to take necessary “days off” to allow the body to rest and heal (Schreiber, 2013).

On the microscopic level, there is evidence that exercise can both cause and attenuate inflammation. Each time we exercise, our muscles incur mini tears - or microscopic damage to our muscle fibers - and our skeletal muscle is damaged and subsequently inflamed (Schreiber, 2013). The purpose of the inflammation would be to repair the exercise-induced damage (Malm, 2001). Strenuous physical activity has been found to interfere with normal levels of circulating thyroid hormones in the bloodstream. In extreme cases of overexercise, thyroid function may even become suppressed, slowing down our metabolism dramatically (Schreiber, 2013).

Individuals struggling with overexerting themselves risks falling prey to overtraining. Symptoms and signs of overtraining include higher resting heart rates, dips or spikes in blood pressure, elevated body temperature, chest pain, changes in metabolism, and dehydration (Schreiber, 2013). Most surprisingly, the bodily duress brought about by excessive physical activity can prompt the brain’s hormonal control centers to inhibit male and female sex organs (Schreiber, 2013). Over the long term, halting reproductive processes in the interest of preserving the reserves of the overexerted individual may result in infertility and osteoporosis (Schreiber, 2013). One study of 2,000 female marathon runners found 24% lacked a regular period, while 10% were completely infertile (Schreiber, 2013).

Overexerting yourself now might not seem dangerous, and the physical consequences of repeatedly overtraining may seem far off. However, it’s clear that though we might not see the damage we’re doing to our bodies now, its impact might last a lifetime. Regardless of fitness levels, we all need to rest to allow our muscle cells to make up for lost ATP (energy to help us move) but so inflammation and microscopic damage of our muscle fibers can heal (Schreiber, 2013).



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