Do you honestly believe that a mere 17.5 grams of additional carbohydrates (the amount found in a 6 oz. glass of grapefruit juice) can cause such metabolic havoc as to completely halt fat burning?? Do you have any scientific proof to support this assertion (I'm asking because you seem big on studies)?
And you questioned my intelligence...
Do you think that Atkins requires that carbs be below 20 grams a day because he pulled that number out of a hat? You can see for yourself that 37 grams a day does not work. You provided the study yourself!
Some require even less. For example, my wife began to steadily lose weight only after reducing her intake to below 20 gms of carbohydrates per day. She also has to strictly watch her calories.