Dieters are often successful at losing weight for about six months, when that dreaded plateau and weight regain happens due to a return to normal eating habits.

The few who successfully maintain weight loss over the long term do so by heroic and vigilant efforts to maintain behavior changes in the face of increased appetite along with persistent suppression of energy expenditure in an omnipresent obesogenic environment.

Polidori et al. Obesity (Silver Spring). 2016 Nov; 24(11): 2289-2295.

If maintaining weight loss is so difficult, why can people with Anorexia continue to lose weight to an extent that harms them? They are a minority population, sure, but I think we can learn something from analyzing how they are wired up.

Habit learning and anorexia

In 2006, Joanna Steinglass and Timothy Walsh from the New York State Psychiatric Institute proposed that habits explain the relentless persistence of food restriction seen in anorexia.

By drawing upon clinical research in patients with anorexia and juxtaposing it to similar research in patients with Obsessive Compulsive Disorder (OCD), Steinglass and Walsh argue that cognitive domains related to implicit learning may be impaired in individuals with anorexia, which reduces cognitive flexibility and impairs the ability to change responses in accord with future events.

Ultimately, this leads anorexic patients to develop repetitive, stereotyped behaviors organized around rules.

Like in OCD, where patients are trying to answer the question, ‘‘How do I know the door is locked?’’ patients with AN are preoccupied with the question, ‘‘How do I know I won’t get fat?’’ Patients with OCD have difficulty learning that the door is locked, and patients with AN have difficulty learning that they do not need to fear excessive weight gain. Thus, restrictive eating behavior may become extremely rule bound and ritualized in an attempt to provide reassurance against an unlikely but anxiety-provoking belief.

Steinglass & Walsh. Int J Eat Disord. 2006 May; 39(4): 267-75.

Once these ritualized behaviors are consolidated, patients with AN may have difficulty learning or developing alternative behaviors. That is, food restriction is initially maintained by conscious effort and a realization of rewards (like a perceived sense of control), which eventually becomes habit through classical conditioning (associating food restriction with rewards regardless of the reward’s presence).

Testing the theory

Steinglass and Walsh’s theory has continued to be supported since it was initially proposed. A review of neuroimaging and behavioural studies that examine the neurobiology underpinning anorexia support the notion that excessive habit formation is an underlying mechanism of anorexia’s pathology.

In 2017, researchers from Massachusetts General Hospital and Harvard Medical School were the first to test a key component of this theory — that habit strength maintains food restriction more so than effortful, goal-directed dietary restraint.

Using correlation analyses on a variety of cognitive tests in 78 anorexic patients, the researchers found that illness duration, diagnosis, and extent of cognitive restraint were not significant predictors of dietary restriction, whereas habit strength was a significant predictor.

Finally, a neuroimaging study published in 2019 compared the functional activity of reward and habit-learning centers of the brain between patients with anorexia and healthy controls. The researchers found clear differences between the groups, with exploratory analyses suggesting that these differences correlated with the expression of clinical symptoms.

Although these findings warrant replication, they provide preliminary evidence demonstrating resting state abnormalities across the ventral and dorsal striatum that lend credence to both reward deficit and habit-centered models of [anorexia].

Haynos et al. Hum Brain Mapp. 2019 Feb; 40(2): 652-662.

Summing up

Evidence continues to support the theory that anorexia involves excessive habit development. The habit of food restriction doesn’t occur overnight, but does occur over time after the initial effortful attempts.

Drawing parallels to you and everyone else, it’s rather suggestive that dedication to a diet, a goal-oriented focus, and classical learning will eventually turn willpower to habit. Change is difficult, but if you stick with it, things get easier.