Brain regulation of appetite in twins [Obesity and eating disorders]

Background: Neural responses to highly energetic food cues are robust and are suppressed by eating. It is not known if neural responsiveness to food cues is an inherited trait and possibly even one that mediates the genetic influences on body weight that have been previously observed.

Objective: We investigated the inherited influence on brain responses to high-calorie visual food cues before and after a meal.

Design: With the use of a monozygotic twin study design, 21 healthy monozygotic twin pairs consumed a standardized breakfast and, 3.5 h later, underwent the first of 2 functional MRI (fMRI) scans with the use of visual food cues. After the first fMRI session, twins consumed a standardized meal, which was followed by the second fMRI. Serial ratings of appetite and food appeal were obtained. An ad libitum buffet was used to measure total caloric and macronutrient intakes. Intraclass correlations (ICCs) were used to test for inherited influences by comparing whether intrapair similarity was greater than interpair similarity.

Results: Body mass index was highly correlated within twin pairs (ICC: 0.96; P < 0.0001). ICCs also showed a strong intrapair similarity for the meal-induced change in hunger (ICC: 0.41; P = 0.03), fullness (ICC: 0.39; P = 0.04), and the appeal of fattening food (ICC: 0.57; P < 0.001). Twins ate a similar number of kilocalories at the buffet (ICC: 0.43; P = 0.02). Before the meal, the global brain activation across regions involved in satiety processing was not more similar in twins than in unrelated individuals. However, significant ICCs were present after the meal (ICC: 0.39; P = 0.04) and for the meal-induced change in activation by high-calorie visual food cues (ICC: 0.52; P < 0.01).

Conclusion: Inherited factors influence both satiety perception and the effect of a meal to alter regional brain responses to images of highly energetic food. This trial was registered at clinicaltrials.gov as NCT02483663.

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