Physical Activity in Eating Disorders: A Systematic Review

Activity-Based Anorexia Dynamically Dysregulates the Glutamatergic Synapse in the Nucleus Accumbens of Female Adolescent Rats

Intense physical activity and dieting are core symptoms of anorexia nervosa (AN). Their combination evolves into compulsivity, leading the patient into an out-of-control spiral. AN patients exhibit an altered activation of nucleus accumbens (NAc), revealing a dysfunctional mesocorticolimbic reward circuitry in AN. Since evidence exists that a dysregulation of the glutamate system in the NAc influences reward and taking advantage of the activity-based anorexia (ABA) rat model, which closely mimics the hallmarks of AN, we investigated the involvement of the glutamatergic signaling in the NAc in this experimental model. We here demonstrate that food restriction causes hyperactive and compulsive behavior in rodents, inducing an escalation of physical activity, which results in dramatic weight loss. Analysis of the glutamate system revealed that, in the acute phase of the pathology, ABA rats increased the membrane expression of GluA1 AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor subunits together with its scaffolding protein SAP97. Recovery of body weight reduced GluN2A/2B balance together with the expression of their specific scaffolding proteins, thus suggesting persistent maladaptive neurotransmission. Taken together, AMPA and NMDA (N-methyl-D-aspartate) receptor subunit reorganization may play a role in the motivational mechanisms underlying AN.

Differential effects of heat in the phases of the light-dark cycle in the activity-based anorexia model

BACKGROUND

This research builds on the studies on ambient temperature as a key influence in the recovery of rodents exposed to the activity-based anorexia (ABA) model. The ABA model is an experimental paradigm in which rodents under a restricted feeding schedule and with free access to an activity wheel show signs that parallel those of anorexia nervosa in humans.

OBJECTIVE

The present study focuses on the effects of applying heat during the different phases of the dark-light cycle in the activity levels, body weight, food intake, body temperature, and recovery rates of 30 male rats submitted to ABA.

METHOD

After reaching a 20% weight loss criterion, animals were randomly assigned to three experimental conditions: (a) continuous warming, (b) warming exclusively during the light phase, or (c) warming exclusively during the dark phase.

RESULTS

Differential effects were found depending on the modalities of warming: in comparison with either light or dark warming, continuous warming significatively decreased activity, facilitated weight gain, and maintained body temperature. Transient effects of warming were found both in the groups warmed either during light or dark periods exclusively.

DISCUSSION

The results suggest that both light and dark warming did not promote recovery in animals exposed to ABA. Evidence about the beneficial effects of continuous warming are in line with previous research and reinforces adding external heat as a useful tool in the treatment of anorexia nervosa.

Development and evaluation of an adapted physical activity program in anorexia nervosa inpatients: A pilot study

BACKGROUND AND CONTEXT

Problematic use of physical activity is frequent in subjects with anorexia nervosa (AN). Although it increases resistance to therapeutic treatment, paradoxically, physical activity in AN can also improve mental and physical health. Based on the literature review we hypothesized that adding an adapted physical activity (APA) program to treatment programs could be more beneficial than a total suppression of physical activities. We designed this open study to evaluate the outcome of AN inpatients after an APA program implementation as well as the perceived effect of APA.

METHOD

Forty-one women with AN (17.2 (±2.5) years old, BMI of 16.86 (±2.0)) were included. An eight-session (1 h30/session/week) standardized APA program was delivered and evaluated by structured questionnaires assessing exercise dependence, perceived physical activity, eating disorder (ED) symptoms, body mass index (BMI), along with an interview before and after the APA program.

RESULTS

Twenty-nine women complete the PA program and evaluation. BMI and perceived PA score significantly increased, ED and exercise dependence scores significantly decreased (p < .01). Participants appreciated the program.

DISCUSSION/CONCLUSION

The inpatient program which included APA program helped AN inpatients in decreasing their ED symptoms and their dependence to PA, without any deleterious effect on BMI. Furthermore, APA was appreciated by participants.

Eating-Disordered Behavior in Adolescents: Associations with Body Image, Body Composition and Physical Activity

Eating disorders (EDs) represent a disparate group of mental health problems that significantly impair physical health or psychosocial functioning. The aim of this study was to present some evidence about the prevalence of eating-disordered behavior (EDB) in adolescents, and explore its associations with body image (BI), body composition (BC) and physical activity (PA) in this age group. Data from 780 adolescents participating in a health behavior in school-aged children (HBSC) study conducted in Slovakia in 2018 were used (mean age 13.5 ± 1.3; 56% boys). Differences in mean values of numerical indicators were evaluated using the independent samples t-test. Differences between nominal variables were assessed by the chi-square test. Pearson correlation was used to describe the associations between all the selected variables. EDB was positively screened in 26.7% (208/780) of adolescents, with a higher prevalence in girls (128/344, 37.2%) than in boys (80/436, 18.3%). Significantly higher means of BI, body weight (BW), body mass index (BMI), body fat mass (BFM), body fat percentage (BFP), body fat mass index (BFMI), fat free mass index (FFMI), and SCOFF questionnaire score (SCOFF QS) were found in those positively screened for EDB. Pearson correlation analysis revealed positive associations between EDB and BI, BW, BMI, BFM, BFP and BFMI. The prevalence of EDB is high in Slovak adolescents. Positive associations between EDB, BI, BMI and fat-related body composition parameters support the idea of a more integrated approach in EDs and obesity prevention and treatment. At the same time, gender differences suggest the need for considering gender-specific strategies aimed at girls and boys separately.

Unexpected Association of Desacyl-Ghrelin with Physical Activity and Chronic Food Restriction: A Translational Study on Anorexia Nervosa

Anorexia nervosa (AN) is a severe metabopsychiatric disorder characterised by caloric intake restriction and often excessive physical exercise. Our aim is to assess in female AN patients and in a rodent model, the co-evolution of physical activity and potential dysregulation of acyl—(AG) and desacyl—(DAG) ghrelin plasma concentrations during denutrition and weight recovery. AN inpatients were evaluated at inclusion (T0, n = 29), half—(T1) and total (T2) weight recovery, and one month after discharge (T3, n = 13). C57/Bl6 mice with access to a running wheel, were fed ad libitum or submitted to short—(15 days) or long—(50 days) term quantitative food restriction, followed by refeeding (20 days). In AN patients, AG and DAG rapidly decreased during weight recovery (T0 to T2), AG increased significantly one-month post discharge (T3), but only DAG plasma concentrations at T3 correlated negatively with BMI and positively with physical activity. In mice, AG and DAG both increased during short- and long-term food restriction. After 20 days of ad libitum feeding, DAG was associated to persistence of exercise alteration. The positive association of DAG with physical activity during caloric restriction and after weight recovery questions its role in the adaptation mechanisms to energy deprivation that need to be considered in recovery process in AN.