I would hope that I am pretty well-versed in metabolic syndrome, so here are my 2c
There does exist a pretty solid consensus on the role of the carbs and insulin theory, however I do not feel that this is the whole story....the reason for this is that there are no physiological reasons why the pathway JSW has peer-reviewed, given a very 6th grader treatment by Lustig, leads to ALL of the symptoms of metabolic syndrome. Simply taking in carbs, glucose in its purest forms even minus fiber, should not cause the metabolic cascade of insulin resistance and cardiovascular sclerosis indicative of the disease. The human body is masterful at processing glucose, as it is the most energy dense, preferred fuel of every cell in the body. It yields 36 ATP per cycle of glycolysis, vs I believe 4 ATP for both beta-oxidation (lipid) and anaerobic creatine reactions (sprints). I am not convinced, as I do not believe the scientific community is, that these processes alone are the rote mechanisms of resistance.
I believe that these studies are a classic case of correlation yielding wishes of causation. Yes, we DO find all of these pathways at work (JSW's Lustig pathway) in those with the disease state, with the liver being taken as the epicenter for what ends up being pancreatic resistance, but this does not mean that the excess insulin/glucose theory LEADS to disease....in much the same way that high cholesterol is FOUND alongside patients with severe atherosclerotic and myocardial pathology, it is more and more proving to be exactly that; a ride-along, not a cause.
I believe, and counsel people as such, that it is in fact a "staged-mechanism" disease. First, a calorie-dense environment of BOTH high sucrose and fat must be present, which overwhelms mitochondrial function as well as the ability for the liver to synthesize fats normally. This leads to a micro-cirrhotic state of the liver, in which PUFA and its inflammatory cascade are allowed to run unchecked....this leads to damage to the vessel walls, the hallmark of metabolic syndrome at the vascular level, but NOT alone due to the glucose toxicity, rather a combination of an inflamed system (from the oxidative cascade being misregulated) now being damaged by something it can normally handle in a masterclass, glucose.
The calling card of the metabolic syndrome cardiovascular system is not, in heart surgeries I have seen with my own eyes, an excess of plaque build-up, as some of the CW would have people believe....the giveaway is just how NARROW their vessels are, due to the vessel basement membrane thickening and pericyte regulator loss over time....in short, it is the inflammation, not the thing actually clogging things up.
As far as causes, I blame it mostly on the hyper-palatability of so many foods that are extremely high in both sugar and fat, especially in regards to PUFA. I believe that even a diet very high in sugar, but low on these fats, would lead to slightly decreased insulin sensitivity by default, but not a disease state. I believe that a diet VERY high in concentrated sugars though, such as those found in sodas and some baby formula, can also overwhelm the system with sheer numbers....this accounts for what started all of Lustig's work as a pediatric endocrinologist: How do you get a 6 month old with metabolic syndrome? There is no PUFA, no candy, no soda....the answer is sucrose in outrageous numbers, found via baby formula cranked full of corn syrup.....in short, either one will get you to the disease state, but the adult inflammatory one I outlined is the shorter route.
As for how I go after it, that would take another novel, and I have laid it out before
"They now look to a single and splendid government of an aristocracy, founded on banking institutions, and moneyed incorporations under the guise and cloak of their favored branches of manufactures, commerce and navigation, riding and ruling over the plundered ploughman and beggared yeomanry." - Thomas Jefferson, 1826