Here is a great article on 23 studies comparing low carbohydrate versus low fat diets. All the studies were randomized, controlled trials and published in respected, peer-reviewed journals. Another thing that stands out in these studies is their consistent results and conclusions, not often found in diet and nutrition research. And yet, there still remains skepticism about the efficacy of the lower carbohydrate diet on weight loss and metabolic effects. What still remains to be determined is if the differences in the metabolic markers (HDL, trigycerides, LDL particle size, etc) will result in less heart disease or at least have a favorable effect on our chronic disease risks, namely diabetes and heart disease. It will be interesting to see this trend continue, but it will be of no worth unless it translates to better heart health in the long run. Additionally, a low-carb diet should be defined; at this point it appears to be an ambiguous term and there are many approaches being followed such as the Paleo diets, low-glycemic diets,, ketogenic diets, etc. etc.
A recent study examined the effects of a low-carbohyrate diet versus a low-fat diet on inflammation, implicated in heart disease among other chronic diseases.