While doing a search last night for some information about one of the complications of Metabolic Syndrome, I stumbled upon an interesting review in the World Journal of Gastroenterology - Non-alcoholic fatty liver disease and the metabolic syndrome: Effects of weightloss and a review of popular diets. Are low carbohydrate diets the answer?
Researchers at the University of Connecticut Health Center, in Farmington, Connecticut, reviewed the role of the metabolic syndrome, especially insulin resistance and obesity in the development of non-alcoholic fatty liver disease (NAFLD), to investigate the effect of weight loss on NAFLD and, finally, to evaluate popular diets and compare them with regard to their effects on the metabolic syndrome and NAFLD.
The above article is fairly long, but the researchers take things step by step and review the degeneative processes that occur in metabolic syndrome. They then look at the various therapies that have been evaluated, "Therapies that have been evaluated include lifestyle changes such as diet and exercise, antioxidants like vitamin E and betaine, cytoprotective agents such as ursodeoxycholic acid, lipid-lowering agents, anti-diabetics, weight-loss agents like orlistat and iron reduction therapy, i.e. phlebotomy. The management of associated conditions, such as diabetes, obesity and hyperlipidemia, is especially important, given their association with more advanced liver disease."
The most common of these therapies is weight loss since it, by itself, often leads to improvements in insulin sensitivity, choleseterol, blood pressure and glycemic control - all problems associated with metabolic syndrome. Their concern, however is that "Improvement in liver biochemistry and ultrasonographic appearance is a consistent finding with moderate weight reduction. However, serum aminotransferases are unreliable markers for follow-up, and do not provide accurate data on prognosis. Worsening of fibrosis can occur even as the levels of transaminases decline. A few studies have evaluated and shown histologic improvement."
After a review of traditional weight loss recommendation studies, they move to "popular diets."
The effects of many popular diets on fatty liver are not known. However, metabolic improvements related to dietary weight reduction may favorably influence NASH. If dietary intervention can positively affect insulin resistance and other features of the metabolic syndrome, it would be important to know which particular diet is most beneficial.
One of the most startling statements in the review "A diet high in carbohydrates results in an increase in blood glucose, insulin and triglycerides, all of which are risk factors for the development of NAFLD."
This was stated after a favorable look at studies that used traditional dietary therapies!
Most researchers are well aware of the danagers of low-fat carbohydrate rich diets and I have to applaud these researchers for stating it here simply - the literature is rich with data that clearly shows low-fat diets do not result in significant improvements, but few will state it - it there in their data, but they simply omit any questions or concerns with "unfavorable" outcomes from low-fat diets.
These researchers continue, "Carbohydrate restriction leads to ketosis resulting not only in weight loss, but also a decrease in blood glucose, insulin and triglyceride levels. Studies have shown these diets to be effective in short-term weight loss. Early weight loss is a result of diuresis associated with ketone and urea nitrogen excretion. However, over time, weight loss is a result of loss of body fat. Proponents believe that these diets have a high satiety level, which make them easier to adhere to. This is very important, as dietary adherence is one of the main challenges faced by dieters. Questions with regard to their nutritional adequacy and long-term effects have been raised. In the short-term, these diets have been found to be safe. "
When reviewing studies that compared a low-fat diet to a low-carb diet, it was found that "Effects on biochemical markers associated with the metabolic syndrome appear to be more favorable with low-carbohydrate diets. In general, these diets show greater improvements in insulin sensitivity, triglyceride and high-density cholesterol levels. It is possible that for patients with the metabolic syndrome, a low-carbohydrate diet may be more advantageous. This, in turn, may positively affect NAFLD."
In their conclusions - "Traditionally, a low-fat diet has been recommended, but recent studies, show greater short-term weight loss and greater improvement in markers of the metabolic syndrome without significant adverse effects with low-carbohydrate diets. This raises the question of whether low-carbohydrate diets should be recommended as part of a weight loss strategy for our patients. At this point, questions regarding the nutritional adequacy and long-term safety remain. While studies have evaluated the effect of these diets on weight loss, cardiovascular and metabolic marker studies are needed to evaluate the effect of these diets specifically on NAFLD."