Depression is a term used to describe a wide variety of conditions involving low mood. Major, atypical and bipolar depression are among the many forms of the disorder, each causing unique physical and emotional symptoms. Depending on the type of depression in question, personal body chemistry and other factors, depression treatments can cause weight loss in some patients.
Depressive Disorders
Major depression involves low mood in combination with appetite loss, anxiety and insomnia. Atypical depression---despite the name---is the most common form of the disorder, affecting about 40 percent of patients, according to Depression Perception. It is essentially the opposite of major depression in that it causes overeating, oversleeping and a general slowing of mental faculties. It is this type of depression that is most likely to result in weight gain.
Types of Antidepressant Drugs
Selective serotonin reuptake inhibitors are the most widely prescribed family of antidepressants. Drugs from this class include Prozac, Zoloft, Lexapro and Luvox among others.
When selective serotonin reuptake inhibitors are ineffective, medications from the tricyclic antidepressant class may be prescribed. Tricyclics are an older class of drugs more likely to cause side effects like weight gain, dry mouth and unwanted sedation. Drugs in this class include Elavil, Anafranil and Tofranil.
Atypical antidepressants include medications like Wellbutrin, Remeron and Desyrel that work by affecting multiple neurotransmitters in the brain. According to E Med TV, about 28 percent of patients taking Wellbutrin experience weight loss of more than 5 pounds, making it one of the treatments most likely to cause weight loss. Monoamine oxidase inhibitors like Nardil and Parnate are generally considered a last resort due to the risk for life-threatening interactions with certain foods and medications.
Pharmacology and Weight Loss
Serotonin directly influences mood, appetite and other states of being and is thought to be deficient in people with depression. Selective serotonin reuptake inhibitors work by preventing the reuptake of serotonin, resulting in increased levels of the neurotransmitter in the brain. As serotonin levels begin to normalize, changes in appetite often occur. Patients with atypical depression, for instance, often experience decreased appetite and increased energy levels, resulting in weight loss.
Tricyclics primarily affect the neurotransmitter acetylcholine, while atypical antidepressants increase levels of various neurotransmitters like norepinephrine and dopamine, which are also thought to play a role in some forms of depression. Atypical antidepressants are more likely to cause weight loss than tricyclics, which include weight gain as a common side effect.
Side Effects
Like all medications, antidepressants can cause unwanted side effects. Selective serotonin reuptake inhibitors often cause decreased libido, nervousness and increased sweating, according to Mayo Clinic. Tricyclic antidepressants can cause side effects like weight gain and drowsiness that are often severe enough to discontinue treatment. Other possible side effects of antidepressants include dry mouth, nausea, insomnia and headache.
Warning
All selective serotonin reuptake inhibitors are required to carry a black box warning---the most serious kind---regarding the increased risk of suicide in some patients taking these medications. If you experience worsening anxiety, depression or thoughts of self-harm while taking selective serotonin reuptake inhibitors, seek medical help immediately.
