how do you know that? There are so many possible confounding variables that make that claim doubtful.

When I avoid carbs, I lose weight. I don't get cravings for the foods that normally led me to overeat. It's an anecdote, so feel free to take it with a grain of sugar, but Taubes and Lustig improved my life a great deal.

Every gram of stored carbs (glycogen) gets stored with ~3g of water. By cutting carbs you use up stored carbs and rapidly lose this water-weight. This is why low-carb diets work so well at first, But it's not fat you're losing.

The first week or two of weight loss is indeed mostly water, but I weight 40 pounds less than when I started avoiding carbs. It works for me.