Summary: A new UCLA study reports that men and women show different patterns of brain activity associated with overeating and obesity.
Source: UCLA.
New research indicates structural and connectivity changes in brain reward networks linked to obesity, and that these changes differ by sex.
Researchers at UCLA examined how elevated body mass index (BMI) correlates with alterations in brain networks that govern reward, salience and sensorimotor processing. The study found that people with higher BMI demonstrate reorganization of these networks in ways that may predispose them to overeating. Importantly, the patterns of brain change differed between women and men, suggesting sex-specific mechanisms underlying excessive intake and obesity.
Key findings
Women with elevated BMI showed greater changes in reward-related regions associated with dopamine signaling and emotional processing. These patterns suggest a stronger role for affective and compulsive eating behaviors in women. Men with elevated BMI exhibited greater structural centrality in sensorimotor areas, including regions that integrate visceral and gut-related sensations, indicating that interoceptive awareness and bodily signals may play a larger role in their eating behavior.
Background
Behavioral and neurobiological research has long linked the brain’s mesolimbic dopamine system to reward-driven behaviors, including eating and substance use. Stress, drug exposure and hormonal differences can alter dopamine signaling and reshape reward circuitry. Such modifications can change how rewarding stimuli are processed and lead to maladaptive behaviors like overeating. The UCLA study extends this framework to obesity, showing that higher BMI is associated with topological changes in brain networks that handle reward, salience and sensorimotor information, with distinct male-female differences.
Methods
The research team analyzed structural and diffusion tensor imaging from 124 adults (61 males, 63 females) without major medical or psychiatric diagnoses. Using graph theory, they constructed anatomical brain networks and measured centrality, a metric reflecting a region’s prominence and information-flow role within a network. Participants were grouped by BMI and sex: males with high BMI, males with normal BMI, females with high BMI and females with normal BMI. Statistical models controlled for age while assessing BMI- and sex-related differences in network centrality across reward, salience and sensorimotor regions.
Results
Across both sexes, individuals with elevated BMI showed increased centrality—greater connectivity—of reward-related structures such as the putamen and salience regions like the anterior insula. Sex-specific patterns emerged as well. Among those with higher BMI, women exhibited higher centrality in amygdala, hippocampus and nucleus accumbens, regions closely tied to emotion, memory and reward valuation. Women also showed increased centrality in anterior mid-cingulate cortex, a salience network node. By contrast, men with higher BMI had greater centrality in putamen and posterior insula, implicating sensorimotor and interoceptive processing in their neural profile.
Implications
These findings suggest that obesity is associated with reorganization of brain networks that integrate reward signals, bodily sensations and salience processing. The sex-related differences highlight that men and women may engage different neural pathways in overeating: women more through emotion-related reward circuits and compulsive patterns, and men more through sensorimotor and visceral processing. Recognizing these distinctions could improve the precision of interventions for obesity by informing sex-specific prevention and treatment strategies that target the most relevant neural and behavioral mechanisms.
The study’s authors include Arpana Gupta, Emeran Mayer, Kareem Hamadani, Ravi Bhatt, Connor Fling, Mher Alaverdyan, Cody Ashe-McNalley, Bruce Naliboff, Kirsten Tillisch, Claudia Sanmiguel, and Jennifer Labus from UCLA, and Carinna Torgerson and John Van Horn from the University of Southern California.
Funding: Research support was provided by grants from the National Institutes of Health’s National Institute of Diabetes and Digestive and Kidney Diseases (DK106528, P50 DK064539, R01 DK048351 and P30 DK041301).
Source: UCLA
Original research: Abstract published as “Sex differences in the influence of body mass index on anatomical architecture of brain networks” in the Journal of Obesity (published online April 25, 2017).
Sex differences in the influence of body mass index on anatomical architecture of brain networks
Background/Objectives:
The brain plays a central role in controlling eating behavior, and imbalance in processing reward and salience can drive maladaptive, reward-driven ingestion that overrides homeostatic needs. This study used graph theory–based network analysis to assess how BMI relates to network measures of integrity, information flow and global communication (centrality) in reward, salience and sensorimotor regions, and to determine whether these relationships differ by sex.
Subjects/Methods:
Structural and diffusion tensor imaging were obtained from 124 adults (61 males, 63 females). Anatomical network properties for reward, salience and sensorimotor regions were calculated. General linear models with contrasts tested for BMI- and sex-related differences in regional centrality, controlling for age.
Results:
Individuals with elevated BMI showed greater anatomical centrality in reward (putamen) and salience (anterior insula) regions across sexes. Sex differences were evident: females with high BMI had greater centrality in amygdala, hippocampus and nucleus accumbens and in anterior mid-cingulate cortex, whereas males with high BMI showed greater centrality in putamen and posterior insula.
Conclusions:
Elevated BMI is associated with sex-specific topological restructuring of reward, salience and sensorimotor brain networks. These results underscore the role of these networks in processing food-related cues and in the development or maintenance of increased ingestive behavior. The observed sex differences support the need to consider sex as a critical factor in understanding obesity and tailoring treatments.