I think diets with names (Atkins, South Beach, etc.) are not as effective as a simple, sensible diet (with 'diet' meaning every morsel that goes down the throat.)
A good health care provider and/or dietician can be a valuable resource. And 20 grams of carbohydrates sounds unhealthy, especially if that regimen lasts for a period of weeks.
I shoot for my daily caloric intake to be 30% protein, 20% fat, and the rest carbs, and under 2000 calories/day total. That's not all that hard to do. And, when I add a long bicycle ride into the mix, I get to eat more that day - maintaining close to the 30/20/50 ratio.