After one year Low Carb advantage vanishes
Well, results of low carb not being clearly superior is likely due to muddying the waters with quite high levels of carbohydrates. In low carb circles the clear limit used for carbohydrates is 150g. That is not an arbitrary number but the estimated amount of glucose that spares protein in full parenteral feeding different than fat, that is, the daily glucose need of our body (ingested or generated de novo from proteins and glycerol) when we are out of ketosis. Beyond this point both fat and glucose have the same sparing effect. Between 150 and 200g is considered moderate in carbohydrates and it is defended by Paul Jaminet for example. Vicente has some blog posts in English commenting upon this misunderstanding in several research papers such as talking about low carb interventions that are not low carb (other and another) or even not so honest reviews and meta-analysis.
[Added on 4/10/2016]
As a matter of fact we can already see the positive effect of a low carb diet at 142g-CHO/day on diabetics even without weight loss in the trial by Gannon & Nuttall.
Of course human beings can thrive at different carbohydrate intake levels. We have Kitavans for example.
Once ill such as with hypertension or diabetes I think low carb high fat should be an approach to check. Feinman et alter think it should be the first approach in diabetes management. Not that it is the only one and we have for instance the high carb very low fat rice diet promoted by Kempner back in the day (via Denise Minger) that seems to have reversed diabetes and hypertension too. I am not sure about a too low fat intake effect on our gallbladders though. As a matter of fact the low-carb diet is the one that has been shown to be a good solution to gallbladders stones (via Dr. Eades).
Of course it would be interesting to see the options evaluated on long term studies. Nevertheless its absence doesn't preclude anyone of trying whatever approaches they are attracted to and checking their physiological surrogate markers to them. Dr. Eenfeldt keeps track of those favoring low-carb high-fat.
With respect to body fat loss there are even more strange approaches like the Shangri-La Diet of late Seth Roberts promoting ingestion of flavorless calories (even water with sugar) in order to hack the weight set point. Not that ingesting them as seed oils is safe.
Potential dangers of too low carb
There are those who think (opinion of Paul Jaminet) that too low carbohydrate consumption may have detrimental effects to our health on the long run.
One of these would be a deficit of substrate (the carbohydrate part) for mucin production. Mucin seems to be used by our gut commensal bacteria.
Either way, it will be a good idea to have them in mind if we go too low carb, just in case.