HIV remains a significant health concern, but the advent of antiretroviral therapy (ART) has transformed it into a manageable chronic condition. However, weight gain and obesity pose a substantial challenge for people living with HIV (PLWH). Moreover, the role of lifestyle has not yet been comprehensively investigated. This review aims to provide an updated perspective on the role of lifestyle factors in weight gain and obesity among PLWH. A systematic search was conducted on Medline, Web of Science, Scopus, and ClinicalTrials.gov according to PRISMA guidelines. Overall, 378 articles were identified, of which 22 studies met the inclusion criteria. No article comprehensively addressed all lifestyle factors, and only 8 (36.4%) evaluated 3 or more factors. Addictions (72.7%), food (34.4%), and physical activity (31.8%) were the most analyzed aspects. An absence of concordance was identified among the articles concerning the timing of assessments, methodologies employed in surveys, and the operational definitions utilized for "weight gain," "overweight," and "obesity." Weight gain in PLWH represents a complex phenomenon necessitating a holistic approach to promote well-being in this vulnerable population.