Food “Addictions”

Loss of control over intake, constant desire (i.e., craving) for a substance, use-associated guilt, and secretive use of a substance are the hallmarks of drug addiction. Many people report feelings of loss of control over eating and obsessive thoughts and craving for food, as well as guilt, depression, and secretive eating in response to loss of control. The Diagnostic and Statistical Manual, 4th edition (DSM-IV) lists provisional criteria for binge eating disorder (which usually occurs in obese individuals, but may occur in lean individuals) and definitive criteria for bulimia nervosa (which usually occurs in lean individuals) that include all of these symptoms. There is no agreement among scientists as to whether the existence of these symptoms in an individual constitutes an addiction to food.

Addiction is a term that really describes the combined physiological, psychological, and social consequences of repeated uncontrolled intake of substances. However, some people use the term addiction to refer to the physiological and/or psychological dependence on a substance. Using this definition, the presence of an addiction can thus be demonstrated by the emergence of physiological symptoms (e.g., shaking, teeth chattering, sweating) or psychological symptoms (e.g., irritability, aggression, depression, crying) upon withdrawal of the substance for a period of time. Researchers have demonstrated physiological “addictive” responses (in rats) to sucrose when provided on a limited and unpredictable basis. In fact, all living creatures are physically dependent on food to sustain life.

Because we all need food to survive, it is difficult to ascribe addiction to certain behaviors toward food. However, recent brain imaging data have shown similarities in dopamine functioning and activation of the reward circuitry of the brain between those experiencing “loss of control” over eating and those addicted to drugs. The difference, however, between food and drugs with respect to addiction potential, lies in the reduced amount of dopamine released upon food stimulation compared to drug stimulation and the shorter duration of dopamine release upon stimulation, which causes a more rapid return of the brain reward circuitry to its normal state compared to that observed with drug use. The different time course for food-induced dopamine effects compared to drug-induced dopamine effects, results in a reduced opportunity for an individual to experience an altered state, or “high,” which fuels continued abuse of the substance. In addition to altered activity in the brain reward circuitry, decreased signaling in the “emotion” centers of the brain due to stress and depression can also promote uncontrolled eating. Carbohydrate- and fat-induced dopamine release in the brain can cause [Page 285]a transient and temporary relief of the stress or depression. This temporary relief promotes conditioned learning that underscores the development of a craving for carbohydrate-/fat-containing food during future periods of stress and/or depression.

Addiction is defined as a loss of control regarding a substance or action. Many people find themselves “addicted” to particular foods.

Besides altered brain responses to food, disorders in peripheral digestion and metabolism can also contribute to a sense of “loss of control” over eating in obese individuals. The peripheral digestive and metabolic systems of the body contribute signals of satiation (stop eating now) and satiety (I've had enough to eat) to the brain. Increased stomach capacity and decreased stimulation of the vagus nerve produce weaker signaling to the brain of satiation (“stop eating” signal) in some obese individual, and insensitivity to hormone-based signals of satiety (I've had enough to eat), such as insulin resistance and leptin resistance, add to reduced “stop eating” signals that are also relayed to the brain.

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