Background: Obesity and type 2 diabetes have been linked to alterations in food reward processing, which may be linked to insulin resistance.
Objectives: In this clinical study, we investigated the respective contribution of insulin resistance, anthropometric measurements, and behavioral factors to brain reward activation in response to visual stimuli.
Design: Food reward-related brain reward activation was assessed with functional magnetic resonance imaging in 39 overweight or obese individuals with impaired fasting glucose, impaired glucose tolerance, or both [22 women, 17 men; mean +/- SD insulin sensitivity index (ISI): 2.7 +/- 1.3; body mass index (BMI; kg/m(2)): 32.3 +/- 3.7; body fat percentage: 40.5% +/- 7.9%; fasting glucose: 6.3 +/- 0.6 mmol/L]. Food and nonfood images were shown in a randomized block design. Brain activation (food compared with nonfood images) was correlated with anthropometric and behavioral variables. Behavioral variables included eating behavior [Three-Factor Eating Questionnaire (TFEQ)] and habitual physical activity (Baecke). Glucose and insulin concentrations, determined during an oral-glucose challenge, were used to assess the homeostatic model assessment for insulin resistance (HOMA-IR) and Matsuda ISI.
Results: Food compared with nonfood brain activation was positively associated with HOMA-IR in the nucleus accumbens, right and left insula, and right cingulate gyrus (P <0.005, corrected for multiple comparisons). TFEQ factor 2 was positively related to food compared with nonfood brain activation in the supramarginal gyrus (P <0.005, corrected for multiple comparisons). Habitual physical activity during leisure time was negatively associated with food compared with nonfood brain activation in multiple regions associated with the attention and reward network (P <0.005, corrected for multiple comparisons).
Conclusions: Individuals with increased insulin resistance and emotional eating or disinhibition showed higher brain reactivity to food cues, which may imply changes in food preference and hyperphagia. Individuals with higher habitual physical activity showed less food reward-related brain activation.
- type 2 diabetes
- insulin resistance
- insulin sensitivity
- food reward
- brain activation
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