This is a dilemma I expect to face a lot over the next few months as I am absolutely committed to losing weight - none of my usual half hearted attempts here this time.
As it's winter, I'd start with soup. Which has the added benefit of being easy to make low calorie. I'm doing weight watchers so will base my menu on that.
I'd do a pea and spinach soup [In a tiny amount of oil, fry a small finely chopped onion and a finely chopped leak. Then add one bag of baby spinach and about 100g of frozen peas and about 1litre of stock (enough to cover peas and spinach generously after the spinach has wilted) . Simmer gently for 10 - 15 minutes. Allow to cool slightly then use a hand blender to liquidise, adding salt and pepper to taste and half a teaspoon of nutmeg. The soup will be a fairly unappetizing dark green at this stage. When serving it (hot), add a table spoon of plain greek yoghurt to each bowl and mix through. Makes it a much nicer colour and adds a lot of flavour. For the men, you can also top with crunch bacon bits]. This soup is 2 points for weight watchers [excluding bacon].
You could also do a butternut soup which is also low in points and can be jazzed up with some spices like cumin, coriander and ginger (even a bit of curry).
For main, I'd do chicken and parma ham bake. This is surprisingly low points as the parma ham goes a long way.
Wrap chicken breasts in a slice of parma ham each and place in a large roasting tray. Around the chicken place baby tomatoes (pricked) and slices of sweet potato. Also toss a few garlic cloves into the dish and sprinkle some thyme or origanum too. By the end, everything should be snug (bulk up with sweet potato and tomatoes). Drizzle with a small amount of olive oil (mainly on the tomatoes and sweet potatoe) and put in a medium oven for about 30- 40 minutes - the parma ham will crisp up and release it's fat to help cook the tomatos and sweet potato. You can stir the vegetables around about half way through if you want to.
I work this out to be about 4 and a half points per person, assuming that you only have a 100g chicken breast for the dieters and bulk up on the tomatos and sweet potato. Serve with some extra green vegetables like green beans or brocolli. You can also serve it with some couscous (possibly just for the men) which will be lovely with the juices from the roasting try. (alternatively, leave out the sweet potato and serve it with mash, but that makes it a lot more calories/points).
For dessert, I'd go for something very chocolatey and intense and small - some kind of chocolate thing made in espresso cups with 70% dark chocolate. I need to investigate this kind of thing myself! Or, try serving frozen yoghurt with fresh fruit.