Shahram Heshmat

Despite documented short-term success, dieting has very low success rates; most dieters regain weight within three to five years. Why do people fail to stick to their diet goals? One answer is that they have self-control problems in the form of a present-biased preference. From a prior perspective, they want to behave relatively patiently, but as the moment of action approaches, they want to behave relatively impatiently.

The field of behavioral economics blends insights of psychology and economics. The basic message of behavioral economics is that humans are hardwired to make judgment errors, and they need a nudge to make decisions that are in their own best interest. Behavioral economics studies demonstrate that rewards are discounted proportionally with their delay. People will make relatively far-sighted decisions when planning in advance, but they will make relatively short-sighted decisions in the moment. The following explains why there is conflict between long-term intentions and short-term actions.

The intention-action gap. People sometimes report feeling as though there are two selves inside them battling for control—one more present-oriented and the other more future-oriented. The planner-self will often choose the largest reward, while the acting-self can be overcome by a desire for a smaller reward that is available sooner. For example, a person might strongly intend to eat a low-calorie diet to stay healthy in the future, but in the moment of decision, he or she chooses French fries, which are more attractive in the short run than a low-fat salad.

Reflective system vs affective system. Self-control may be conceptualized as a struggle between two subsystems. The reflective (rational) system operates mostly consciously, uses logical rules, and is deliberative. The impulsive (affective) system is associative and acts spontaneously without consideration for broader consequences. Self-control failure implies that these two systems come into conflict. If the deliberative system is able to attend to the conflict, the person may be able to resist the impulse.

Willpower. When people exert willpower, they inhibit their normal, typical, or automatic behavior. In general, willpower refers to effortful control over our own behavior. Engaging in acts of self-control draws from a limited resource of self-control, which becomes depleted over time, just as a muscle becomes tired after exertion. This model of willpower implies that to improve self-control, we need to carefully conserve energy.

The role of the emotional system. Strong feelings (e.g., hunger, stress, and cravings) shorten the time horizon and make us impatient. These feelings create something like a temporary preference for a certain course of action. The change in preferences, in turn, causes an individual to prefer immediate rewards, in which the benefits are delivered first and the costs come later, over options that have the opposite pattern.

The immediacy effect. Proximity to temptation is one of the powerful determinants of self-control. Consumption items that are immediately available seem to exert a disproportionate pull. This explains why a wide range of situations (cues) such as the sight, touch, or smell of a desirable object produce impulsive reactions.

Lapse-activated consumption. A common pattern of self-control failure for chronic dieters occurs when they “fall off the wagon” by violating their diets. Once the diet is broken for the day, dieters appear to give up control, perhaps anticipating starting their diets anew the next day.

Projection bias. Projection bias is the tendency for people to underappreciate the effects of changes in their states, and hence falsely project their current preferences onto their future preferences. For example, when people predict immediately after dinner how much they will enjoy a delicious breakfast the next morning, they understate the pleasure. They tend to reason that they are full now, so they will be full the next morning. Thus, people overestimate ability to resist temptations.

Modern life. Technological changes have brought about a progressive shift away from physically demanding tasks to knowledge-based work requiring enhanced mental effort. The increased cognitive demand is associated with emotional stress (such as burnout), which is known to favor overconsumption of comfort food as a coping mechanism. As a result, modern life requires a far greater amount of self-control.

In sum, behavioral economics suggests that self-control failure occurs whenever the balance is tipped in favor of an impulsive system involved in reward and emotion. For example, negative mood and cue reactivity to appetizing foods interfere with self-control because they disrupt the reflective mind, thereby tipping the balance. However, we are not powerless, and becoming self-aware of these forces helps to improve our self-control ability.


Shahram Heshmat, Ph.D.,
Contributing Editor 
Associate Professor, Dept. of Public Health, University of Illinois at Springfield 
[email protected]