Brain activation and affective judgements in response to personal dietary images: An fMRI preliminary study

Multimodal Neuroimaging of Obesity: From Structural-Functional Mechanisms to Precision Interventions

PURPOSE

Obesity's metabolic consequences are well documented; however, its neurobiological underpinnings remain elusive. This systematic review addresses a critical gap by synthesizing evidence on obesity-induced neuroplasticity across structural, functional, and molecular domains through advanced neuroimaging.

METHODS

According to PRISMA guidelines, we systematically searched (2015-2024) across PubMed/Web of Science, employing MeSH terms: ("Obesity" [Majr]) AND ("Neuroimaging" [Mesh] OR "Magnetic Resonance Imaging" [Mesh]). A total of 104 studies met the inclusion criteria. The inclusion criteria required the following: (1) multimodal imaging protocols (structural MRI/diffusion tensor imaging/resting-state functional magnetic resonance imaging (fMRI)/positron emission tomography (PET)); (2) pre-/post-intervention longitudinal design. Risk of bias was assessed via the Newcastle-Ottawa Scale.

KEY FINDINGS

1. Structural alterations: 7.2% mean gray matter reduction in prefrontal cortex (Cohen's d = 0.81). White matter integrity decline (FA reduction β = -0.33, p < 0.001) across 12 major tracts. 2. Functional connectivity: Resting-state hyperactivity in mesolimbic pathways (fALFF + 23%, p-FDR < 0.05). Impaired fronto-striatal connectivity (r = -0.58 with BMI, 95% CI [-0.67, -0.49]). 3. Interventional reversibility: Bariatric surgery restored prefrontal activation (Δ = +18% vs. controls, p = 0.002). Neurostimulation (transcranial direct current stimulation (tDCS) enhanced cognitive control (post-treatment β = 0.42, p = 0.009).

CONCLUSION

1. Obesity induces multidomain neural reorganization beyond traditional reward circuits. 2. Neuroimaging biomarkers (e.g., striatal PET-dopamine binding potential) predict intervention outcomes (AUC = 0.79). 3. Precision neuromodulation requires tripartite integration of structural guidance, functional monitoring, and molecular profiling. Findings highlight neuroimaging's pivotal role in developing stage-specific therapeutic strategies.

Brain functional and structural magnetic resonance imaging of obesity and weight loss interventions

Obesity has tripled over the past 40 years to become a major public health issue, as it is linked with increased mortality and elevated risk for various physical and neuropsychiatric illnesses. Accumulating evidence from neuroimaging studies suggests that obesity negatively affects brain function and structure, especially within fronto-mesolimbic circuitry. Obese individuals show abnormal neural responses to food cues, taste and smell, resting-state activity and functional connectivity, and cognitive tasks including decision-making, inhibitory-control, learning/memory, and attention. In addition, obesity is associated with altered cortical morphometry, a lowered gray/white matter volume, and impaired white matter integrity. Various interventions and treatments including bariatric surgery, the most effective treatment for obesity in clinical practice, as well as dietary, exercise, pharmacological, and neuromodulation interventions such as transcranial direct current stimulation, transcranial magnetic stimulation and neurofeedback have been employed and achieved promising outcomes. These interventions and treatments appear to normalize hyper- and hypoactivations of brain regions involved with reward processing, food-intake control, and cognitive function, and also promote recovery of brain structural abnormalities. This paper provides a comprehensive literature review of the recent neuroimaging advances on the underlying neural mechanisms of both obesity and interventions, in the hope of guiding development of novel and effective treatments.

Neural activity in self-related brain regions in response to tailored nutritional messages predicts dietary change

Overweight and obesity have become international public health problems, so there is an urgent need to implement effective interventions that prevent these concerning health issues. Designing personalized (tailored) dietary communications has become one of the most effective tools in reducing unhealthy eating behavior, when compared with one-size-fits-all messages (untailored). However, more research is required to gain a complete understanding of the underlying mechanisms by which tailored nutritional messages elicit reductions in unhealthy dietary behavior. To the best of our knowledge, our study may be the first to use neuroimaging, namely functional magnetic resonance imaging (fMRI), aiming to evaluate the neural basis of tailored and untailored nutritional messages and assess how these neural responses predict unhealthy food intake reduction after a month receiving tailored nutritional messages. To that goal, 30 participants were scanned while reading tailored and untailored nutritional messages. Subsequently, for a month, they received tailored interventions encouraging healthy food intake. The neural findings reveal that when compared to untailored communications, tailored messages elicit brain networks associated with self-relevance, such as the precuneus, the middle temporal gyrus, the hippocampus, the inferior orbitofrontal cortex (OBC), the dorsomedial prefrontal cortex (dMPFC), and the angular gyrus. Interestingly, among these self-related brain areas, the dMPFC, OFC, angular gyrus, and hippocampus forecast reductions in unhealthy food intake after a one-month tailored intervention for the cessation of unhealthy eating. These results may offer implications for clinicians, practitioners, and/or policymakers who should implement substantial efforts in creating individualized campaigns focused on their target's perceived needs, goals, and drivers in relation to eating healthy to reduce overweight issues. This research therefore constitutes a step forward in showing a direct association between the neural responses to tailored nutritional messages and changes in real-life healthy eating behavior.