What is Cognitive Dietary Restraint?
Cognitive Dietary Restraint (CDR) is the perceived continuing effort to restrict dietary intake to manage body weight. It’s referred to the ongoing mental energy directed at limiting food, abiding by pre-determined portion sizes or other rules to modulate weight, rather than internal cues such as hunger and satiety (1). Although traditionally the literature has focussed on weight, mental efforts used to restrict dietary intake may also be for the aim of improving “health” and following a "pure" diet.
For example, you're at a restaurant and the waiter puts a bowl of delicious, warm, doughy bread at the centre and suddenly there’s the potential of that mental energy required to resist the bread when really you just want to dunk it in a whole load of olive oil. It may also look like the switching on of the food police which might give x, y, or z reason for avoiding the bread.
A key point about CDR is that it's related to the mental energy around food and not the actual actions that follow (e.g. restricting or going ahead and “breaking a diet rule”) (2). For example, even if you were to go on and eat the bread, CDR has still occurred. Essentially it's a mental process and not what's taken place in subsequent actions (2). Whether someone goes on to eat the bread or not doesn’t matter, if there’s a lot of inner dialogue going on about whether to eat the food or not, CDR has already occurred.
CDR and stress
The subjective experience of high dietary restraint (even just as a mental effort) may be a subtle but chronic psychological stressor, leading to increased release of the stress hormone cortisol (3). Over time, elevated cortisol has detrimental effects on many body systems i.e. the digestive system and immune system (4). CDR is so important to understand because studies have shown high levels of CDR have been associated with (5):
Immune dysfunction.
Heightened anxiety.
Increased risk for stress fractures (6).
Compromised performance and memory.
Interestingly, these are the negative impacts that we typically associate with restriction, an energy deficit and reduced body weight. However, these consequences of CDR may occur irrespective of BMI.
As CDR increases:
-> one’s tendency to feel higher levels of deprivation (from food/ energy intake) also increases.
-> which increases the desire/ likelihood to engage in counter-regulatory eating behaviours.
(this is the psychological tendency for someone to eat more just after having eaten a larger amount of food, which is the opposite to the “normal” pattern for eating whereby someone would eat less if they have already just eaten) (7).
Research supports this. A study found that participants who use dietary restriction and follow food rules went on to eat more cookies after eating what they perceived to be a larger portion of pizza whilst participants with fewer food rules and restrictions ate fewer cookies after the pizza. (8).
This supports the idea that when restrained eaters believe they may have broken one of their food rules, they may experience a “blown it” attitude which means they go on to eat more because it feels like the day is “ruined” (9).
Failing to adhere to CDR efforts (i.e. eating from the bread basket when mentally trying to resist) may also result in a ‘spiral’, meaning folks attribute their “failure” to lack of willpower. This can result in further restriction and rules which may increase the risk of subsequently breaking more rules and experiencing more counter-regulatory eating. Over time, this harmful cycle of repeated attempts to engage in more restriction and experiencing increased CDR may promote binge eating and purging (7).
Although CDR is related to the mental energy required to resist food and not the actual actions that follow e.g. restricting, these negative impacts may be just as harmful. CDR requires a lot of brain space and is ultimately exhausting! If you feel that you may be suffering from CDR please know that help and support is available. You can find out more about the services we offer at the Isa Robinson Nutrition Clinic here.
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