Overweight and obesity are an increasing tendencies worldwide. Disordered Eating Behaviors (DEBs) are feeding dynamics commonly present on them, as in Feeding Disorders (FD). These eating and body conditions are highly correlated with specific psychopathological symtoms, such as anxiety and depression, weight-related shame and stigma, and academic stress. Additionally, electroencephalographic findings suggest that weight- and eating-related conditions may be mediated by neural pathways specific to executive functions, such as selective attention and inhibitory control. Therefore, this cuasi-experimental design, pre- and post- measurement, longitudinal cross-sectional study aims to evaluate the effect of a training on psychological flexibility skills, based on Acceptance and Commitment Therapy (ACT) processes, on psychological, electroencephalographic and body composition measures.

This study is a Randomized Controlled Trial (RCT), according to the guidelines for CONSORT randomized controlled trials. Participants will be randomized and double-blinded. Stage 1: Clinical Trials Registration. Involvement Participant eligibility assessments (n = 30). Permanence analysis of participants and inclusion and exclusion criteria. Randomized groups (n = 30 ). Blinded 1: Group assignment; A = Wait List, control group, B = Psychological Flexibility Training Intervention Group. Randomization of participants to the intervention Blind Group 1: BGroup 2. Homologous rate of group assignment will be maintained. Psychometric, neuropsychological and neurophysiological measures will be used. The following assessment instruments will be used:

Neuroimage: Global Brain Activity (GBA) electroencephalography neurophysiological recording of each participant will be performed, using food pictures taken from selected from the International Affective Picture System (IAPS) in an artifact-free room using a 14-channel Emotiv EPOC. Only 8 channels are going to be monitorized: Fp1, Fp2, F3, F4, F7, F8, P3 & P4, and only frequencies between 8-12, and 13 to 30, for Alpha and Beta, respectively. The datasets will be stored in the research mainframe for subsequent property extraction and offline analysis using artificial intelligence tools and techniques.

Executive Function: Neuropsychological Battery of Executive Functions and Frontal Lobes, 3rd Edition (BANFE-3). This is an instrument that allows exploring the functioning of 16 executive processes: Metamemory, figurative meaning comprehension, abstract attitude, verbal fluency, productivity, cognitive flexibility, visuospatial planning, sequential planning, inverse sequencing, encoding control, self-directed working memory, verbal working memory, visuospatial sequential working memory, inhibitory control, rule following and risk-benefit processing. The exploration of these processes is performed through 14 tasks that were adapted from paradigms already tested in neuropsychological and neuroimaging studies in previous international studies. According to the authors, the test has sufficient convergent and clinical validity. The reliability assessed through inter-rater agreement is .80. The parameters were obtained from its application in a sample of Mexican participants without atypical functioning conditions. The tests of interest for this study are described below: Stroop Effect: It is considered an indicator of inhibitory control functioning since it evaluates the participant's ability to stop an automatic response and execute a non-dominant one. In this version, a sheet is used in which columns of six words are presented with color names that presuppose two conditions, in the neutral condition the person should only read the word that corresponds to the color of the ink with which it is printed on the sheet, while in the conflict condition, the participant must name the color of the ink with which the word is printed avoiding reading it, in this condition there is no concordance between the word and the color of the ink so that a situation of cognitive conflict is generated. Letter Sorting: This task is based on the Wisconsin letter sorting test and has been associated with cognitive flexibility functioning. Here, the participant is asked to look at a base sheet containing the image of four cards that have geometric shapes that vary in shape, color, and number of shapes on each card. The participant is given a deck of 64 cards with the same characteristics and is asked to place each one of them under the card that he/she believes corresponds to the card on the sheet based on its characteristics. The evaluator can only answer yes or no according to a criterion established by the evaluator, and that will change progressively but is not perceptible to the individual. The hability of the participant to modify his/her classification criterion according to the feedback provided by the evaluator is explored, especially in the conditions of criterion change.

Eating Bevarior: Binge Eating Scale (BES), validated in mexican population, has been selected to messure binge eating, composed of 16 items, and two factors, 1) Cognitive Manifestations and 2) Behavioral Manifestiations. In regards to restrictive eating, emotional eating and external eating, we've selected the Dutch Eating Behaviour Questionnarie, validated in mexican population. Additionally, to messure Cognitive Restrain, Emotional Eating and Uncontrolled Eating the Three-Factor Eating Questionnaire-R18 (TFEQ-R18), valitaded in mexican population, has been selected.

Beck Anxiety Inventory. For the measurement of depression, the Beck Hopelessness Scale is used, composed of 20 items and three factors validated in Mexican population.

Inclusion Criteria:

• Between 18 and 30 years old.
• Currently enrrolled in university studies.
• Attend at least 80% of the intervention sessions.

Exclusion Criteria:

• Having a diagnosis of personality disorder.
• Failure to attend post-assessment.
• Currently attending psychological therapy or psychiatric care..