High-fat and high-sugar consumption alters the brain’s reward system

Why do some foods become so difficult to give up? The answer may lie in the brain’s reward system. A review by Aslıhan Atar, a researcher at the Research Institute for Health Sciences and Technologies (SABITA) at Istanbul Medipol University, entitled “Neurobiological Consequences of High-Fat High-Sugar Diets on the Mesocorticolimbic System: a Narrative Review” and published by Springer, examines the effects of diets high in fat and sugar on the brain and eating behavior.

According to the study, these foods can activate the brain’s reward system in the short term, increasing pleasure and the desire to eat. Frequent and prolonged consumption, however, may alter the brain’s response to reward. These changes may be associated with intense food cravings, the need to consume more to achieve the same level of pleasure, and difficulty controlling eating behavior.

WHY DOES THE BRAIN CRAVE FATTY AND SUGARY FOODS?
The brain’s reward system shapes how we learn from pleasurable experiences and our desire to repeat them. One of the most important components of this system is dopamine, which plays a role in motivation and reward anticipation.

Foods high in fat and sugar can strongly activate the brain’s dopamine system. Human and animal studies evaluated in the review suggest that foods combining both fat and sugar may produce a stronger reward response than foods containing either fat or sugar alone.

This also helps explain why we may want to eat certain foods even when we are not physically hungry. Eating behavior is shaped not only by the body’s energy requirements but also by pleasure and the anticipation of reward.

LONG-TERM CONSUMPTION MAY AFFECT THE REWARD SYSTEM
The effects of a diet high in fat and sugar may not be limited to the pleasure experienced during consumption. Evidence suggests that prolonged consumption may weaken the brain’s response to reward. As a result, a stronger stimulus or greater consumption may be required to achieve the same level of pleasure.

Animal studies indicate that prolonged consumption of foods high in fat and sugar is associated with reductions in certain receptors within the brain’s dopamine system and with decreased interest in naturally pleasurable activities.

The review also notes that dopamine is more closely associated with “wanting” a food, whereas the brain’s opioid system is associated with the “pleasure” experienced while consuming it. The interaction between these two systems helps explain why high-calorie foods in particular can exert such a powerful appeal.

EVEN SEEING FOOD CAN INCREASE THE DESIRE TO EAT
Hunger is not always necessary for the desire to eat to arise. The sight or smell of a food, or even an environment that we associate with it, can gradually become a cue that activates the brain’s reward system.

For example, seeing a frequently consumed food high in fat and sugar can trigger the desire to eat even when a person is already full. Repeated consumption can establish a strong association between such cues and the pleasure derived from eating.

The study also draws attention to eating behavior that occurs during periods of stress or emotional fluctuation. Some individuals may turn to high-calorie foods to make themselves feel better even when they are not hungry. Evidence also suggests that prolonged consumption of diets high in fat and sugar may affect brain regions involved in decision-making and behavioral control.

THERE ARE SIMILARITIES TO FOOD ADDICTION, BUT NO DEFINITIVE CONCLUSION
The study notes several similarities between the effects of foods high in fat and sugar on the brain and those of addictive substances. These similarities include the reward system becoming less sensitive over time, increased cravings in response to sights and smells associated with food, and greater difficulty controlling eating behavior.

This process is associated with patterns such as eating despite not being hungry, difficulty controlling the amount of food consumed, and continuing the same behavior despite negative consequences.

However, the study emphasizes that the available scientific evidence is insufficient to conclude that foods high in fat and sugar directly “cause addiction.” Since a substantial proportion of the findings are based on animal studies and long-term human research remains limited, further investigation is required.

RESPONSES MAY VARY FROM PERSON TO PERSON
Another point highlighted by the study is that not everyone responds to foods high in fat and sugar in the same way. Genetic characteristics, environmental conditions, and individual differences can influence both eating behavior and the response of the brain’s reward system.

The review also evaluates studies suggesting that certain medications that act on the brain’s pleasure and reward systems may reduce cravings for high-calorie foods and uncontrolled eating behavior in some individuals. However, responses to these treatments may vary from person to person.

THE STUDY OFFERS A NEW PERSPECTIVE ON THE FOOD ADDICTION DEBATE
Atar’s study examines the effects of diets high in fat and sugar not only in terms of body weight and metabolic health but also from the perspective of the brain’s reward system and eating behavior.

The study brings together existing scientific evidence on how food cravings develop, why high-calorie foods can exert such a powerful appeal, and how prolonged consumption may affect behavioral control.

At the same time, it emphasizes the need for more comprehensive human studies before definitive conclusions can be reached regarding food addiction.