Friday, July 4, 2008

Metabolic Syndrome

In several recent posts we've mentioned something called "metabolic syndrome." What is metabolic syndrome?

Metabolic syndrome is not a disease, but rather a set of symptoms that frequently appear together in patients as they grow older. Typically these symptoms include obesity, low HDL cholesterol levels, high triglyceride levels, high glucose and insulin levels, and high blood pressure. As these symptoms worsen, patients with metabolic syndrome frequently progress to type 2 diabetes and cardiovascular disease. If we could somehow prevent or reverse the symptoms of metabolic syndrome, it seems logical that we could correspondingly decrease the incidence of type 2 diabetes and cardiovascular disease.

Obesity is one of the characteristics of metabolic syndrome. Because obesity is easy to observe, it is commonly assumed that metabolic syndrome is caused by obesity. However, a careful inspection of the markers associated with metabolic syndrome reveals that they are all related to insulin resistance.

While weight loss will relieve some of the symptoms of metabolic syndrome, weight loss is notoriously difficult to accomplish and even harder to maintain. The good news is that carbohydrate restriction, even in the absence of dramatic weight loss, is effective in alleviating all of the aspects of metabolic syndrome.

In a study published in the New England Journal of Medicine, 63 obese patients were assigned to a low-carb/high-fat/high-protein diet or to a high-carb/low-fat/low-calorie conventional diet. They were given little follow-up to mimic typical dieting conditions. The graph above summarizes the findings. Light blue bars represent low-carbers at 6 months and dark blue bars represent low-carbers at 12 months. Light red bars represent high-carbers at 6 months and dark red bars represent high-carbers at 12 months.

Although the low-carb group lost more weight than the high-carb group, at 12 months the difference was not significant. The low-carb group experienced a slight decline in systolic blood pressure while the high-carb group experienced a slight increase. HDL cholesterol was significantly higher and triglycerides were significantly lower and in the low-carb group at 12 months. Finally, there was less insulin released in the low-carb group at 6 months, though the difference was no longer significant at 12 months.

Jeff Volek and Richard Feinman have compiled a review of over 30 dietary studies, tabulating the effects of carbohydrate restriction on the markers associated with metabolic syndrome. As we might expect, some studies show great differences and other show little or none. However, taken together, the studies show that while both low-carb diets and conventional diets are associated with an overall decrease in weight, low-carb diets also typically produce the following
  • an increase in HDL cholesterol
  • a decrease in triglycerides
  • a decrease in glucose levels
  • a decrease in insulin levels
  • a decrease in blood pressure

In other words, a review of the scientific literature shows that dietary carbohydrate restriction is a reproducible way to improve the features of metabolic syndrome.


Laurie Cags said...

Thanks for printing this as it's important for so many people.
You may also want to tell your readers about the effort being taken to better educate the public by asking the NIH to fund more low carb research.
You can find the petition here:

Keep up the good work!

Stargazey said...

Thanks for the reminder, Laurie!

I signed the petition a while ago, but we need to get as many signatures as possible. (To all my readers--just copy and paste Laurie's URL into your browser and take a look at the site if you're interested in signing the petition. Or you can click here.)

The impetus for the petition is a diabetes study called ACCORD. According to Science News, Targeting Blood Sugar To Near-normal Levels Increases Risk Of Death In Persons With Diabetes At High Risk, ACCORD Trial Shows. If that were true, wouldn't it mean that those of us who walk around all the time with normal blood sugars are also at an increased risk of death?

Well, no. It turns out that the ACCORD strategy for restoring the diabetics to normal blood sugars was intensive use of medication, not a change to something like the low-carb lifestyle. According to a brief article by Eric Westman and Mary Vernon, "In our clinical practices, we frequently see individuals who are instructed to eat high carbohydrate diets and use intensive injectable hypoglycemic therapy, and they are susceptible to hypoglycemic reactions. Severe hypoglycemic reactions are associated with an increased morbidity and mortality". In other words, the ACCORD study tried to control high blood glucose without adequate provision for the dangers of accidentally producing low blood glucose through overmedication.

Rather than abandon all attempts at normalizing blood glucose levels in type 2 diabetics, those of us who follow the low-carb lifestyle would like to see the National Institutes of Health at least consider the possibility that a change in diet could provide an effective alternative therapy for these people. If you agree, please take the time to sign the petition.

feinman said...

Thanks for citing our article. I do think it is a very important observation but was not widely cited in the scientific literature. I also feel that the ACCORD study is a wake-up call for the importance of alternative approaches to the problems of diabetes and metabolic syndrome. The petition that Lauri referred to has proved to be an important window into actual practice in the population and we think it will have an impact at the NIH.

I urge people to use the petition to have your voice heard on a broader perspective for government-funded research.

Richard Feinman
Professor of Biochemistry
SUNY Downstate Medical Center

JayCee Botha said...


Just a quick question please...

Why did the insulin DROP at all (below 0) for a high carb diet in both 6 and 12 months ? Doesn't Insulin go UP in a high carb diet?

Thank you for a great blog!


Stargazey said...

Hi, Jaycee! I think the confusion may be caused by the term "diet." In the U.S., "diet" is commonly used with reference to a weight loss program. That's how it's being used in this study--the high-carb diet group ate 1200 to 1500 kcal per day for women and 1500 to 1800 kcal per day for men, with approximately 60 percent of calories from carbohydrate. The high-carb diet group was therefore getting 180-270 grams of carbohydrate per day.

If the subjects were typical Americans, before they started the study they were probably eating a high-carb "diet" in the other sense of the term "diet"--what a person usually eats. The difference was that, pre-study, they were eating 60% of a higher number of calories as carbs. So when they participated in the study, they decreased the absolute number of carbs they ate, and their insulin secretion correspondingly decreased from its baseline value.