lucinda, my perspective might be an unpopular one... but I don't think you should give up on the way you enjoy the Sabbath, even if that celebration is centered in part around the enjoyment of food and drink. Maybe instead of curtailing your intake on Friday nights to the point where your enjoyment of that time is decreased, a better option could be making your weight loss plan a little more strict during the rest of the week so that you have more "wiggle room" on Friday nights. Or, keep your intake especially light during the day on Friday so that you can truly enjoy the food, wine and time with your family after sundown without any worry or guilt.
Just a thought.