Could you tell me if someone drinks three or four glasses of wine a night, will they inevitably put on weight?

A problem?: First of all that sounds like a lot of wine for anyone, especially a woman. If your additional wine consumption calories are greater than your total caloric expenditure, then you will have surplus and gain weight. Alcohol doesn't add any nutritive benefit, so they are empty calories. Rule of thumb: to maintain weight, calories consumed have to equal calories expended. Excess is stored.