Obesity is a major global health challenge with significant implications for individual and collective health, affecting quality of life and health systems. It is related to a wide range of chronic diseases, including cardiovascular disease, type 2 diabetes, hypertension and some cancers, making it an independent risk factor for mortality in many developed nations. This article explores the potential of neurofeedback training (NFT) as an intervention for maladaptive eating behaviors and related psychological factors, particularly in post-bariatric surgery patients.
The Obesity Epidemic and Emotional Eating
Statistics suggest that the prevalence of obesity has reached epidemic proportions. In adults, the Body Mass Index (BMI) is commonly used as an indicator of body fat, with values between 25 and 29.9 kg/m2 indicating overweight, while a BMI of 30 kg/m2 or higher is used to define obesity. Difficulties in managing emotions and the prevalence of negative emotions emerge as key elements in the genesis and maintenance of obesity. Emotional eating (EE) is defined as the tendency to overconsume food in response to negative emotional states, such as anxiety, sadness, stress or anger, rather than in response to physiological hunger. This behavior involves a shift in attention from internal emotional experience towards immediate external stimuli, particularly food, with the aim of reducing self-awareness and regulating affect. Emotional eating, therefore, represents a form of dysfunctional coping strategy, in which food intake has the function of alleviating emotional distress rather than satisfying an energy requirement. These dysfunctional behaviors not only complicate weight management but may also negatively influence perceived self-efficacy in the context of weight loss.
Bariatric Surgery: An Effective Intervention with Limitations
One strategy often considered to bring about significant changes in weight loss in patients with severe obesity is bariatric surgery. Bariatric surgery has proven to be an effective option, leading to significant body weight reduction and improvements in associated comorbidities. Bariatric surgery is considered an effective therapeutic intervention for the treatment of severe obesity characterised by BMI ≥ 40 kg/m2 or ≥35 kg/m2 in the presence of comorbidities. Several techniques, such as gastric bypass and sleeve gastrectomy, significantly reduce stomach capacity and limit nutrient absorption, leading to substantial weight loss. An additional study demonstrated that bariatric surgery can result in a body weight reduction of between 20% and 30% of the initial weight within the first 12-18 months post-operation. Furthermore, bariatric surgery is associated with improvements in obesity-related comorbidities, such as type 2 diabetes, hypertension and sleep apnoea, thus contributing to a better quality of life and reduced mortality. However, it is important to recognise that some patients may not achieve the expected level of weight loss or may experience significant weight regain. Outcomes may vary widely between individuals, and some patients may require additional interventions or support to maintain their results. In particular, recent evidence indicates that even after surgery, a proportion of patients continue to present maladaptive eating behaviours and difficulties in emotional regulation, which may compromise long-term weight maintenance.
Neurofeedback Training: A Non-Invasive Approach to Brain Modulation
As an alternative methodology in the treatment of patients with obesity, NeuroFeedback Training (NFT) is included, which represents a promising brain training methodology that relies on neurophysiological principles to offer a non-invasive approach to the control and modulation of brain activity. Specifically, during the training process, the neurofeedback system analyses specific neural parameters, while a computational interface provides the patient with a continuous stream of real-time information about their physiological brain activity (e.g., through visual and/or acoustic signals). The patient is then called upon to self-regulate these parameters, receiving immediate feedback indicating whether or not the training goals have been achieved. The scientific literature has documented the complex neurobiological processes that regulate eating behaviour, evidencing the central role of specific brain circuits in the modulation of appetite, food reward and inhibitory control. Neuroimaging studies and research on the neuromodulation, of eating behaviour, suggest that obesity cannot be considered only as a metabolic or behavioural issue, but should be addressed by taking into account brain influences on body weight regulation mechanisms. These findings show the importance of considering the neural basis of nutrition in the treatment of eating disorders, emphasising the need for a multidisciplinary therapeutic approach that integrates neuroscience, psychology and nutrition science to develop more effective and targeted interventions. While NFT has been investigated in populations with binge eating and obesity, demonstrating reductions in pathological eating behaviours, the existing evidence is limited to heterogeneous samples that do not include post-bariatric surgery patients. This represents a significant gap, since the clinical profile of post-bariatric patients differs substantially from that of general obese populations. In fact, despite substantial weight loss, many individuals continue to experience maladaptive eating patterns, emotional dysregulation, and vulnerability to relapse, which can undermine long-term surgical outcomes. Therefore, to our knowledge, no studies have systematically evaluated the use of NFT in this clinical subgroup. Based on these premises, the conceptual hypothesis of the present study is that NFT, by enhancing self-regulatory mechanisms through targeted modulation of brain activity, may reduce emotional eating and improve psychological well-being in post-bariatric surgery patients.
Neurofeedback Protocol and Study Design
A study was conducted involving thirty-six patients who underwent sleeve gastrectomy, divided into an NFT group (N = 18) and a control group (N = 18). A total of 36 patients were recruited at the General Surgery Unit of the University Hospital of Messina. All participants had previously undergone bariatric surgery, specifically sleeve gastrectomy, and provided written informed consent before taking part in the study. For each participant, data were collected on biographical information, body mass index (BMI), clinical and psychiatric history, the presence or absence of binge eating episodes, and details related to their bariatric procedure. Inclusion criteria required that participants were eligible for bariatric surgery according to clinical guidelines, had already undergone sleeve gastrectomy, did not present current episodes of binge eating, and reported emotional eating behaviours in the postoperative period. This study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee at the University Hospital of Messina (Prot. 68/16 approved 1 August 2016). In addition, this study was conducted according to the diagnostic and therapeutic procedures for the multidisciplinary clinical management of obesity (PDTA No. 2755 approved DG 1261/20 December 2024). The neurofeedback protocol adopted in the study was based on alpha-theta training. Brain activity was recorded via two electrodes placed in the following leads: left central occipital (C3-O1) and right central occipital (C4-O2). The positioning of the electrodes was chosen to target both the sensorimotor (central) and visual (occipital) cortical regions. The sensorimotor cortex contributes to self-regulatory control and habitual motor patterns, which are potentially relevant in modulating orofacial and eating behaviours, while the occipital areas are involved in the visual processing of signals including food and body image. Neurofeedback targeting alpha-theta activity in these regions can improve emotional regulation and inhibitory control over food-related stimuli, promoting adaptive eating behaviours. The treatment was conducted for a total of 10 sessions, each lasting 30 min, on a weekly basis, for a total duration of two months and two weeks. To ensure adequate conductivity, an electrically conductive gel was applied to the participants’ skin. The protocol employed a frequency band between 6 and 9 Hz, with the aim of increasing alpha and theta waves in the open-eye condition. During the training, patients were presented with visual stimuli (geometric shapes, diagrams, graphs, linear distortions, pictures, slides and videos) and auditory stimuli (audio fragments, natural sounds, voice information and sound distortions). In addition, audio and video feedback messages allowed participants to monitor their progress in real time. At the end of each session, the electrodes and cap were removed. During the study, patients were assessed at two points in time: one month after surgery (T0) and after 10 neurofeedback sessions (T1). All 18 participants demonstrated high adherence to the protocol, completing it regularly without any dropouts and attending all scheduled sessions in full.
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Assessment Tools
Assessments were performed at baseline and after 10 NFT sessions, using the Eating Disorder Inventory (EDI) and the Body Uneasiness Test (BUT).
Eating Disorder Inventory (EDI)
The Eating Disorder Inventory (EDI) is an instrument used to assess the main psychological characteristics associated with eating disorders. The scale is not intended for the specific diagnosis of an eating disorder, but rather for the evaluation of traits considered significant for understanding such conditions. The instrument consists of 64 items divided into eight subscales: the first three examine attitudes and behaviours related to weight, eating, and body image, while the remaining five assess broader psychological traits that are clinically relevant to eating disorders. Participants respond to each item using a 6-point Likert scale, ranging from always, usually, often, sometimes, rarely, to never. These responses are then recoded into a 4-point scale (0-3), where 0 is assigned to the three least symptomatic responses, and 3 represents the most symptomatic response. The eight subscales of the EDI are:
- Drive for Thinness: This subscale measures the excessive desire for thinness, which often leads to restrictive and unhealthy weight-loss behavior.
- Bulimia: This subscale assesses behaviors related to bulimia nervosa, including episodes of binge eating and subsequent compensatory behaviors such as self-induced vomiting. It measures the frequency and intensity of binge periods and the level of anxiety or shame related to these behaviors.
- Body Dissatisfaction: This subscale measures the degree of dissatisfaction a person feels about their body. Individuals with high scores in this subscale are more likely to perceive their body as imperfect or ‘wrong’. It focuses on feelings of physical and psychological discomfort with various areas of the body and concerns about fitness.
- Ineffectiveness: This subscale explores the sense of ineffectiveness that often accompanies eating disorders. It is a measure of how the person perceives his or her ability to handle stressful situations and achieve goals.
- Perfectionism refers to the tendency to set unrealistically high standards for oneself and to feel disappointed or anxious when these standards are not met.
- Interpersonal Distrust: This subscale measures the level of distrust a person has in others and in their social relationships.
- Interoceptive Awareness: This subscale explores a person’s ability to perceive and interpret physiological body signals, such as hunger, satiety, tiredness and pain.
- Maturity Fears: This subscale measures fears related to growth and maturation, including physical and psychological changes associated with adulthood.
Body Uneasiness Test (BUT)
The Body Uneasiness Test (BUT) is a self-report questionnaire consisting of 71 items, divided into two sections. The first section, BUT-A, consisting of 34 items, assesses aspects such as:
- Weight phobia: Evaluates excessive preoccupation with body weight and fear of gaining weight.
- Body image concerns: Measures the level of dissatisfaction with one’s physical appearance, including distorted perceptions of one’s body, feelings of shame and discomfort about specific body parts.
- Avoidance: Assesses the avoidance strategies put in place to avoid confronting one’s body.
- Compulsive self-monitoring: Measures the tendency to repetitively and obsessively control one’s physical appearance.
- Depersonalization: Assesses the sense of alienation from one’s own body, as if it did not belong to the person or was detached from them.
Study Results: NFT Shows Significant Improvements
Compared with the control group, the NFT group showed significant improvements; specifically, reductions were observed in EDI subscales such as Drive for Thinness (p = 0.023, d = 0.51), Bulimia (p = 0.008, d = 0.92), Body Dissatisfaction (p = 0.015, d = 0.52), Ineffectiveness (p = 0.002, d = 0.89), Perfectionism (p = 0.006, d = 0.70), Interpersonal Distrust (p = 0.008, d = 0.82), and Interoceptive Awareness (p = 0.001, d = 0.91). Significant reductions were also found in BUT subscales including Weight Phobia (p = 0.041, d = 0.84), Body Image Concern (p = 0.039, d = 0.90), Avoidance (p = 0.027, d = 0.83), Compulsive Self-Monitoring (p = 0.013, d = 0.83), and Depersonalisation (p = 0.033, d = 0.85).
EEG Neurofeedback Paradigms for Binge-Eating Disorder
Specific alterations in electroencephalography (EEG)-based brain activity have recently been linked to binge-eating disorder (BED), generating interest in treatment options targeting these neuronal processes. A randomized-controlled pilot study examined the effectiveness and feasibility of two EEG neurofeedback paradigms in the reduction of binge eating, eating disorder and general psychopathology, executive functioning, and EEG activity. Adults with BED and overweight (N = 39) were randomly assigned to either a food-specific EEG neurofeedback paradigm, aiming at reducing fronto-central beta activity and enhancing theta activity after viewing highly palatable food pictures, or a general EEG neurofeedback paradigm training the regulation of slow cortical potentials. In both conditions, the study design included a waiting period of 6 weeks, followed by 6 weeks EEG neurofeedback (10 sessions à 30 min) and a 3-month follow-up period. Both EEG neurofeedback paradigms significantly reduced objective binge-eating episodes, global eating disorder psychopathology, and food craving. Approximately one third of participants achieved abstinence from objective binge-eating episodes after treatment without any differences between treatments. These results were stable at 3-month follow-up. Among six measured executive functions, only decision making improved at posttreatment in both paradigms, and cognitive flexibility was significantly improved after food-specific neurofeedback only. Both EEG neurofeedback paradigms were equally successful in reducing relative beta and enhancing relative theta power over fronto-central regions. The results highlight EEG neurofeedback as a promising treatment option for individuals with BED.
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Study Design and Procedures
This randomized-controlled trial used a within-between subjects design with participants being randomized to one of two active intervention groups (between-subjects), measured at four different time points (within-subjects). All participants were assessed at baseline, after the 6 weeks waiting period (pretreatment), after neurofeedback training (posttreatment), and after a 3-month follow-up period. Participants were randomized into a food-specific and a general neurofeedback condition using two stratification indices: weight status (BMI < 30 kg/m2 versus BMI ≥ 30 kg/m2) and severity of BED according to the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5 [1]; BED full syndrome versus BED of low frequency and/or limited duration). Participants were blind for other possible group allocations, but it was not possible to keep the experimenter blind during treatment, assessment, and analysis. Written informed consent was obtained from all participants prior to study participation and after detailed explanation of study procedures. Based on the results of Schmidt and Martin [9, 10], an a priori power analysis suggested medium to large within group effects of neurofeedback on overeating tendencies (0.89 ≤ d ≤ 1.6); therefore, a sample size of n = 18 individuals with BED was required per group to detect medium-to-large sized reductions in OBEs (f = 0.30) with adequate power (1 − β = 0.80).
EEG Neurofeedback Protocols
Participants received 10 individual EEG neurofeedback sessions. Each session lasted approximately 1 h, including 30-min active training. The aim was to train twice a week in the first 4 weeks and once a week during weeks 5 and 6. All participants were asked not to eat 2 to 3 h before each session to reduce between-subject variance in food deprivation. Based on the findings of a systematic literature review and the findings by Schmidt and Martin [9, 10], the EEG neurofeedback protocol aimed at reducing fronto-central high beta activity (23 to 28 Hz) while increasing theta activity (5 to 7 Hz). The EEG was derived from the training sites Fz, Cz, Fc1, and Fc2 in reference to the mastoids with a sampling rate of 256 samples per second (sps). A fast Fourier transformation was used to determine the activity over the fronto-central area. Eye-movements were controlled by an Electrooculogram (EOG), and low and high bandpass filters were implemented. As active comparison condition, a general paradigm, SCP training was used, which is well established in the treatment of ADHD [18, 39]. SCP training targets the ability to self-regulate cortical activation and inhibition [18]. In line with the standard SCP protocol, Cz was used as training site, which was referenced to the mastoids with a sampling rate of 128 sps. Since SCP training is sensitive to eye movements, an electrooculogram (EOG) real-time correction was implemented. Additionally, low and high bandpass filters were employed.
Infraslow Neurofeedback for Food Craving
Theoretically, the inflexibility of the DMN towards alterations in energy dynamics could be a reason for the heightened craving for food among some obese individuals, particularly those with symptoms of food addiction. In reference to addiction, the relationship between PCC activity and craving has been described in many aspects of craving including drug, alcohol, smoking, and food. Here, a novel approach using infraslow neurofeedback may be effective for modulation of PCC activity and craving.
Methods of Infraslow Neurofeedback Study
Participants between the ages of 18 to 60 years were recruited from advertisements in local newspapers and on notice boards with an invitation to participate in a potential therapeutic method to curb food craving. Interested individuals were invited to the neuromodulation clinic of the University Hospital of Otago, Dunedin, New Zealand for a screening procedure. All eligible participants had to score 3 or more on the YFAS and had to have a body mass index (BMI) that is equals to or above 25. Exclusion criteria included: (1) major weight gain or loss (>5 kgs) in the last 6 months; (2) recent significant head injuries; (3) females who are or intend to become pregnant; (4) co-morbidities associated with obesity (e.g., diabetes, obstructive sleep apnoea); (5) centrally active medications; or (5) neurological or psychiatric disorders. The study was a four-week, randomised, double-blind, parallel trial. Different researchers conducted the EEG assessments/craving status to those carrying out the treatments. All researchers who had contact with participants were blinded to treatment allocation to minimise possible bias. All patients were blinded to treatment assignment. Participants were randomised to either ISF-N training or placebo. At pre-treatment (T0), food craving was measured using the validated Food Craving Questionnaire (FCQ-S) and resting state brain activity sampled using EEG. Height was measured without shoes to the nearest 0.5 cm using a stadiometer and body weight assessed using a Bioelectric Impedance Analysis (BIA) machine. Participants received either ISF-NF or placebo three times a week for two weeks totalling up to six sessions. The first training session was for 10 minutes and the subsequent 5 sessions were 20 minutes each. Two-days after the last treatment session (T1), participants were asked to complete the same battery of questionnaires and to perform another resting state EEG.
Infraslow Neurofeedback and Placebo Administration
ISF-NF and placebo ISF-NF were administered with participants sitting in a comfortable chair with their eyes closed. After careful skin preparation, the appropriate Comby EEG (Ag/AgCl) cap was placed on the participant’s head with reference electrodes at the mastoids. The impedances of the active electrodes were kept below 5 kΩ. Before the training period, participants were instructed to relax and listen to the sound being played. For the ISF-NF group, a distinct tone was used for ISF reinforcement at the PCC. Reward threshold was adjusted in real time at above 90%. In other words, for 90% of the time, a sound was played (reward) when participant’s brain activity meets the infraslow magnitude (threshold). was administered. The simulation protocol played a sound at random. Before the first training session, a simple explanation was given to participants. They were informed that research has shown that the brain of individuals with a BMI of more than 25 functions a little differently from normal-weight individuals and that we were trying to train their brains to normalize. The sound they hear during neurofeedback reflects whether they were doing well.
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