Zhukov said:
That's the Atkins/Paleo kinda thing right? No sugers or carbs? Supposed to do something whacky to your metabolism so you burn fat?
Does it work?
Short answer is yes, long answer is "yes*".
Like most diets, it'll work through sheer elimination of 90% of the crap you were probably eating. Processed foods of all varieties will be out, as will fast foods and sugary treats and fattening breads. You kinda cannot help but lose weight on a diet like that. Since the body stores water with glucose, you'll also shed water weight like a champion (most people will point to Keto as a "rapid weight loss" diet for this reason, although THAT weight loss is of course illusory...start carb loading again and all that water comes back). You do eventually metabolize fat for energy more efficiently (turning it into glucose) although whether or not the body goes more aggressively after its own fat stores or just uses incoming fats is beyond me. I suspect the latter.
Why the asterisk?
Atkins "failed" for a reason. You'll hear a lot of Keto fanatics talk about being on a diet where they can eat all the bacon and ribeye they want, and...well...that's not a long term recipe for health. You can still overeat ketogenically, and make stupid dietary choices. Second, it's expensive as hell to eat little other than produce and meat and dairy, especially if you shop organic. Third, it's not the most varied diet and most people will eventually rebel. It was number two that caught up with me in the end...I wanted/needed bread so I could make some affordable lunches. I still keep carbs quite low though...under 100g a day where I can help it, and virtually none of that from sugars (outside of fruit). I was under 30g on keto, which can be tricky to get to.
I dropped about 30 pounds in 1.5 months on keto, but I was also cutting calories REALLY aggressively as mentioned (because I have no patience). I think a more natural weight loss rate would be about 2lbs a week, which is pretty close to what my GF saw when she ate the diet with me (assuming you weren't eating back all your calorie reduction in the form of a stick of butter with every meal). It's a good 'cleanse' diet to go on to kickstart a new healthy living regimen since it gets a lot of trash out of your diet, but like all diets it only has value insomuch as people use it to springboard into something sustainable.
So, is it good for weight loss? Yeah. Is it a sustainable long term lifestyle? Probably not, save for the fanatic few. I actually think it's a good way to transition into eating less carbs though, as the almost total abandonment of them for a few months makes the little bit I have now seem absolutely decadent, rather than a pauper's portion.
Thursdays Boot Camp and Saturdays a P-90X type class; I also get bored every so often on those off days and go play on the elliptical or some cardio that's not running). 
