Coffee with half and half. There are a few carbs in the 1/2 and 1/2, but not much.
ETA:
I was in a hurry earlier so I didn't go into my experience with lo/no-carb eating.
I have done it, and I have done it for lengthy periods of time. Once, post baby to lose pregnancy weight (I'd gained 50 lbs). It is hard at first, and yes, you are tired a bit at first. But after a week or so, my energy was way up. You have to be sure to get adequate sleep though.
I found that any time I "indulged" in things carb laden, I felt AWFUL. Really... just AWFUL. And I'd need a nap. Birthday party, and a have a big slice of cake and small serving of ice-cream... a handful of chips b/c that is what the snack food was.... UGH. It was awful.
I also found that if I had 2 or 3 eggs in a veggie/cheese omelet for breakfast, that I really wouldn't be hungry until 1 or 2 pm. Then a piece of LIGHT bread (most have 7 carbs per slice) with egg salad or peanut butter, or tuna salad (without relish in it)... and I was good until dinner.
I didn't even need snacks. But I learned also to carry a snack size ziplock baggie of cashews or peanuts or almonds or walnuts with me. Because when you need food, you need it in a hurry, or you can start to feel yucky and end up grabbing a Snickers bar or something terrible for you.
I did lose weight. And it works and I felt great when I did it, both times. I stayed at 30 grams of carbs per day or less. For months at a time. I ran into problems when I tried to reintroduce a few carbs (to stay below 50 grams)... that was just too many and it was like being an addict. I could basically have almost NONE, or I had no control at all.
My husband still basically lives with a modified version of this. He doesn't eat many starches and enjoys sugary sweet treats rarely. He prefers greek yogurt (highest protein content for yogurts, and low fat and low carb) for his "dessert" every day. He loves Kashi products and Zone bars. And he tries to only eat "light" bread, except when we enjoy a loaf with olive oil and spices. :)
Fresh green salads, seeds/nuts, whole fruit (not juices) and very little processed starch of any kind. We L. grilled foods: chicken, pork, steak, fish, and tonight-- grilled meatloaf!