The risks of smoking are generally inflated by researchers, precisely because it's either difficult in any given study, or said researchers would rather not control for multiple variables between populations. I.e., smokers tend to have significantly worse diet and exercise in comparison with non-smokers. If a person is obese and eats terribly and they smoke, then have a heart attack then the smoking is automatically the primary cause of death.  That said, the findings of this study in no way contradict either the NCS or CBL diets.  These diets are only ULC for the first 10 days.  While they're ULC during parts of the week, they aren't ULC diets.  CNS is meant to be a temporary fat loss diet only, and the 5 day average of total carb intake isn't ULC.  Once you lose the fat on CNS there's no dietary advantage to remaining on a high protein, low carb diet.  You simply don't over eat, eat more of your calories in the evening, and don't eat a lot of low-GI foods that cause long insulin spikes that reduce the period that the body is burning fat. Kiefer explicitly states that he assumes a person will go back to eating more carbs regularly after losing weight on CNS. CBL simply shifts around when different proportions and combinations of macronutrients are eaten over a week, and is higher carb than most diets.