How do some drugs like anti-depressants cause weight gain as a side effect? My doctor told me, even if I’m not increasing my calorie consumption, i still may gain weight. How does that work?
In: 1
Weight gain is a biologic process, designed to protect you from times of low food supply. It’s controlled by complex chemical pathways that regulate your metabolism, how much energy is made available to power your muscles and how much is stored for later. Some medications upset that balance, giving symptoms like fatigue and weight gain.
Depends on the drug, but generally they just cause increased food intake – https://pubmed.ncbi.nlm.nih.gov/8006246/. Drugs like mirtazepine are notorious for this. Some antipsychotics can have other negative metabolic effects
if it causes fatigue + weight gain, then it’s usually causing your body to store energy as fat even when it’s not “excess” energy – so you feel tired (because you don’t have enough energy) and gain weight (because you’re making fat with the energy you are aren’t “allowed” to use).
If it only causes weight gain it probably just increases your appetite so you end up eating more food or reduces your metabolic rate so each calorie goes farther, and I’m sure there are other pathways as well.
While the general rule of weight change = Calories in minus calories out is accurate, there are a LOT of very complex pathways that determine your appetite (which regulates calories in), your metabolic rate (which regulates how many calories you use while idle), your digestion speed (how efficiently you get calories out of the food you eat), your fatigue/activity level (which determines how active you are and will change your calorie expenditure, etc. etc, and antidepressants have whole body effects that will almost certainly affect at least one of these systems in some way.
Latest Answers