Currently in the United States there is an obesity epidemic. The obesity epidemic is of particular importance to psychiatrists due to the fact that many of the psychotropic drugs they prescribe are associated with weight gain. There are various reasons for this including using particular combinations of drugs and diet, however. One study, focusing on 98 patients with affective psychosis or schizophrenia, found that recipients of atypical-antipsychotic drugs experienced a 7% weight gain in one year. There are several other studies that have explored the relationship between weight-gain and psychotropic drugs. Here is an excerpt of an article from Journal Watch that discusses some of these studies:
Some weight-related research might augur psychiatric pharmacogenomics, allowing clinicians to identify patients who are likely to gain weight when taking certain medications. In an animal study, the binding of antipsychotic drugs to histamine H1 receptors paralleled their likelihood of increasing appetite. Clozapine and olanzapine, both strongly associated with weight gain, increased hypothalamic AMP-kinase, which regulates food intake through H1 receptors. Atypical antipsychotics might increase appetite and therefore weight gain through this mechanism, which could become a target for treatment. Other receptors might be involved in antipsychotic-induced weight gain. Increased waist circumference, a core component of the metabolic syndrome, was associated with three polymorphisms of the serotonin 2C receptor gene.
Eating more, especially foods that pack a lot of calories into a small volume, is undoubtedly one mechanism of medication-associated weight gain. Animals given high-fat foods showed increased expression of striatal FosB, an early gene product involved in reward signaling. After withdrawal of high-fat or high-carbohydrate foods, animals showed stress responses mimicking those seen after withdrawal from substances that cause physical dependence. Animals also endured an aversive environment to obtain high-fat foods. Any strategy to prevent or treat weight gain must involve an appreciation of the potent effect of food on reward mechanisms.