There’s no evidence that HRT causes weight gain, although weight gain is common around the time of the menopause. This is because the body attempts to expand fat cells to produce more oestrogen and compensate for the ovaries producing less. 

Supplemented oestrogen side effects can include bloating, breast tenderness, swelling, leg cramps, nausea, headaches, and vaginal bleeding. These normally settle after a few weeks, however. Side effects of progestogen include mood swings, depression, acne, back and tummy pain, breast tenderness and vaginal bleeding, but these are usually short term.