This is the third review in our series examining the connection between osteosarcopenic adiposity/obesity (OSA/OSO) syndrome and health impairments. The objective here was to examine whether there is a causal and/or bidirectional relationship between OSA and some chronic diseases. The search (in PubMed, Scopus, and WoS), screened for articles from their inception to the end of February 2024. Of n=859 articles retrieved, eleven met the eligibility criteria (having all three body composition compartments measured-bone, muscle, adipose tissue and being conducted in adult humans with chronic disease). The selected articles included four assessing OSA and cancers, one each assessing OSA and HIV, Cushing's disease (CD), chronic kidney disease (CKD), pulmonary function, and two for alcohol abuse-caused liver disease, as well as one 6-year study showing the progression to OSA over time. There was a positive relationship between OSA and each of the chronic diseases, as well as a possible bidirectional relationship between OSA and cancers. The evidence linking OSA with HIV, CD, CKD, liver disease, and pulmonary function, was insufficient to derive firm conclusions about their causal/bidirectional relations. This review emphasizes the need for a multidisciplinary approach in the management and treatment of chronic diseases where body composition assessment should get full attention. To close the knowledge gap, more studies about the role of OSA in chronic diseases are needed.