No, It's OK, You Can All Go Back To Your Atkins*
Turns out being fat is bad for you again after all. Phew!
*Note: the above is stated purely in the spirit of comedic hyperbole. Do not, repeat do not adopt the inexplicably still-undiscredited Atkins diet, nor any of its monstrously wrongheaded progeny. Your body burns glucose for energy, people. It gets glucose from breaking down complex carbohydrates. Protein is made of amino acids, which are also necessary to your body's healthy function, but not as fuel. If you weren't 'meant' to eat carbohydrates, your body wouldn't be evolved to rely on them for fuel. That unpleasant bad breath problem people on Atkins suffer from? Indicator of a little thing called 'starvation ketosis': your body digesting its own tissues for lack of glucose.
Human beings are omnivores; we have evolved to derive our various nutritional requirements from a variety of different food types. Cutting out any one type entirely is unrealistic, unsustainable and patently unhealthy. The fact that you may be losing weight does not mean you are healthy, nor that you will be able to sustain the weight loss when you (inevitably) return to a more balanced eating pattern.
Losing weight is brutally fucking difficult, there's no two ways about it, and the temptation is strong to subscribe to a plan that offers simple guidelines ("Only Ever Cabbage Soup!"), or draconian measures ("Only Ever Cabbage Soup!"), or unlimited if circumscribed freedom ("All The Fat & Protein You Can Stomach"). But these measures are based on a category error about human metabolism (see above), they put serious stress on your metabolism and they pretty much never work over the long haul. The only reliable way of losing weight healthily and sustainably I've ever seen is, if you'll forgive my stating the obvious: a) reducing the quantity of food you eat; b) paying attention to the nutritional quality of same (i.e., lots of fruit and veg, not so much with the fats and sugars); and c) getting regular, sweaty, heartpounding exercise. Boring and preachy and assishly difficult though it may be, I don't know of anything else that really works.