No — hormone therapy does not cause weight gain for most women. Multiple well-designed studies, including the Women's Health Initiative, found no association between hormone therapy and weight gain. Some women find it actually helps with weight management by slowing the redistribution of fat to the abdomen that commonly occurs during menopause.
Why the confusion: Weight gain during menopause is common, but it's primarily caused by the hormonal changes of menopause itself, declining muscle mass with age, and lifestyle factors — not hormone therapy.
What some women notice: A small number experience mild bloating or fluid retention when first starting — this is temporary and usually resolves within a few months. It is not the same as gaining fat.