The Psychological Effects of Strength Exercises in People who are Overweight or Obese: an Updated Literature Review and Meta-analysis

In 2016, a literature review to examine the psychological effects of strength exercises for people who are overweight or obese was conducted, incorporating 17 included studies. Although some positive results were found, the authors concluded that there is a strong need to accumulate more evidence before drawing conclusions. Therefore, the current review aimed to update the overview of existing literature on this topic repeating the same procedures. Additional relevant literature (updated search #1 on 6 April 2022, and #2 on 19 January 2024) was identified by use of the PubMed, PsycINFO, the Psychology and Behavioural Sciences Collection, and SCOPUS databases. Following the original procedures, this review focused on studies with an independent identifiable effect of strength exercises on psychosocial determinants in people with overweight or obesity. Risk of bias was assessed using the Effective Public Health Practice Project Quality Assessment Tool. Effect sizes and corresponding variance estimates were extracted or calculated for the main effects of strength exercises on psychological outcomes. In total, 27 studies (10 additional studies compared to the 2016 review) representing 12,861 participants were included. In addition to the eight broad categories of psychological outcomes (psychological disorders, inhibition, mood, outcome expectations, quality of life, self-efficacy, self-esteem, and stress), two more outcome categories (motivation and executive functions) were identified. No large differences were found between the original and updated literature review: some weak positive effects were found for inhibition, self-efficacy, self-esteem, and psychological disorders but not for the other categories. In conclusion, the literature on the effects of strength exercises on psychological outcomes is - almost 8 years after the original review - still fragmented and more evidence is needed to draw profound conclusions. Future research may consider that the psychological effects of strength exercises might be stronger among people who are overweight or obese when they are in contexts in which they can engage in favorable comparisons with normal-weight counterparts.