Well, this is a very individual thing. When I was young, I could eat anything and not gain weight. But as I've aged, I really have to limit things. And I am a firm believer that overeating carbs contributes to weight gain when we use insulin. When we eat more carbs than we actually need, the extra blood sugar is converted to body fat and insulin actually amplifies this fat storage.
And when we want to lose weight, we want to not just lose any weight, we don't want to lose muscle mass, we want to lose bodyfat. So I think it is actually a good idea focus on diets that help with fat loss. And I think there are two key elements to those diets. The first is simple, the diet should be protein sparing, you should get enough protein so that all your dietary needs for protein will easily be met and you won't burn up any muscles during your diet. You don't want to eat too much, but certainly get enough.
The second element is what you ask. How many carbs to eat. I think that the answer lies in making sure that you can keep your blood sugar rise from meals really well controlled and that within 2-3 hours of your meal you can attain a "normal" blood sugar (70-140 mg/dl or so). Excess carbs in your meal will be taken up as bodyfat and if your blood sugar remains elevated for hours after your meal your body will just lay down extra bodyfat.
And finally, our bodies naturally burn fat. Overnight we don't eat while we sleep, our bodies burn fat. Try to optimize the amount of fat burning time during the day (this is the ketosis that Claire mentions). Ketosis kicks in when you have a really well controlled blood sugar and low insulin levels. I've taken to doing intermittent fasting. As to how many carbs, I usually get about 50g/day. But everyone is different.
ps. Note that I said nothing about eating fat and although some people believe that calorie restriction is important, I'm not a believer.