Both hypothyroidism and hyperthyroidism are linked to an increased risk of anxiety and depression, although the causal relationship is unclear. The efficacy of the treatment of both varies and is controversial. In addition, certain psychotropic drugs such as antipsychotics and lithium can influence thyroid function. In patients with eating disorders, especially restrictive eating disorders, low energy intake together with the low fat mass associated with lower leptin production may affect the hypothalamic-pituitary axis. This can cause hypogonadism with secondary osteoporosis and also alters other hormonal axes such as the somatotropic axis or oxytocin production, for example. Many psychiatric diseases are associated with a greater vitamin D deficiency and, thus, osteoporosis. There is a bidirectional relationship between depression on the one hand and obesity and type 2 diabetes on the other. Also, in patients with schizophrenia or bipolar disorder, there is a higher prevalence of diabetes, obesity, and metabolic syndrome, mainly related to a sedentary lifestyle and the use of antipsychotics (mainly clozapine and olanzapine). In fact, the main cause of death is cardiovascular disease in both psychiatric disorders.