Eli5: If gaining weight is simply the result of calories in and out, then why does taking certain medications (birth control, anti-depressants) commonly lead to weight gain?

Question

Eli5: If gaining weight is simply the result of calories in and out, then why does taking certain medications (birth control, anti-depressants) commonly lead to weight gain?

In: Biology

Answer 1

Various hormones levels in your body will effect how many calories you burn while at rest(calories out). If you don’t also alter how many calories you’re consuming(calories in) you’ll suddenly be consuming the same but gain weight because of the lower calorie out.