Based on the search results, the key points regarding the connection between testosterone levels, immune health, and weight control are:
Testosterone has an immunosuppressive effect, meaning higher testosterone levels in men are associated with a weaker immune response compared to men with lower testosterone levels and women.[1][2][3] This could help explain why men are generally more susceptible to infections than women.
However, the immunosuppressive effects of testosterone may provide an evolutionary advantage for men. The search results suggest that a somewhat weakened but not overly strong immune response may be more beneficial for men, who are more prone to injuries and infections from physical competition and traditional male roles.[2] An overactive immune response can also be damaging, as seen in women being more susceptible to death from systemic inflammatory conditions like sepsis.[2]
In terms of weight control, the search results indicate that genetically higher free testosterone levels are associated with decreased body fat and increased bone mineral density in men.[4] This suggests testosterone may play a role in regulating body composition, though the long-term effects on health outcomes remain unclear and require further study.[4]
In summary, higher testosterone appears to have a suppressive effect on the immune system in men, which may have evolutionary advantages despite increasing susceptibility to infections. Testosterone also seems to influence body composition by reducing body fat, but the full implications for health require more research.[1][2][3][4]
Citations:
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7735617/
[3] https://www.nature.com/articles/nri.2016.90
[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7591257/
[5] https://www.broadwayclinic.com/article/immunocompetency-hormones-find-out-the-interconnection