ScienceDaily (May 10, 2009) — Moderate calorie restriction causes temporal changes in the liver and skeletal muscle metabolism, whereas moderate weight loss affects muscle, according to a new study in Gastroenterology, the official journal of the American Gastroenterological Association (AGA) Institute. In addition, researchers found that short-term calorie restriction (CR) with a low-carbohydrate diet caused a greater change in liver fat content and metabolic function than short-term CR with a high-carbohydrate diet.

Insulin resistance is the most common metabolic complication associated with obesity and is associated with an increased risk of developing non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes. Although an energy-deficit diet is the cornerstone of therapy for obesity, the most appropriate macronutrient composition of diet therapy needed to improve metabolic health remains controversial.

"Our data underscore the complexity of the metabolic effects of calorie restricition with diets that differ in macronutrient composition, and demonstrate differences among organ systems in the response to calorie restriction and subsequent weight loss," said Samuel Klein, MD, of the Washington University School of Medicine and lead author of the study. "Our findings help explain the rapid improvement in glucose levels observed after low-calorie diet therapy and bariatric surgery," he added.

In the present study, 22 obese patients were randomized to a high-carbohydrate or low-carbohydrate energy-deficit diet. A euglycemic-hyperinsulinemic clamp, muscle biopsies and magnetic resonance spectroscopy were used to determine insulin action, cellular insulin signaling and intrahepatic triglyceride (IHTG) content before, after 48 hours and after ~11 wks (7 percent weight loss) of diet therapy. An euglycemic-hyperinsulinemic clamp is a widely used experimental procedure for the determination of insulin sensitivity.

Researchers found that short-term CR caused a rapid decrease in IHTG content, an increase in hepatic insulin sensitivity and a decrease in endogenous glucose production rate, whereas longer-term CR and a moderate 7 percent weight loss improved skeletal muscle insulin sensitivity in conjunction with an increase in cellular insulin signaling. The effect of moderate CR in obese patients with either a low-fat or low-carbohydrate diet on metabolic function is a continuum, with differential effects on specific organ systems.

Related Stories

Low-carb Diets Alter Glucose Formation By The Liver (Oct. 21, 2008) — A new study shows that a low-carbohydrate diet changes hepatic energy metabolism. When carbohydrates are restricted, the liver relies more on substances like lactate and amino acids to form glucose, ...  > read more

Low-carbohydrate Diet Burns More Excess Liver Fat Than Low-calorie Diet, Clinical Study Finds (Jan. 20, 2009) — People on low-carbohydrate diets are more dependent on the oxidation of fat in the liver for energy than those on a low-calorie diet, researchers have found in a small clinical ...  > read more

Calorie Restriction Does Not Appear To Induce Bone Loss In Overweight Adults (Sep. 27, 2008) — Young adults who follow a diet that is low in calories but nutritionally sound for six months appear to lose weight and fat without significant bone loss, according to a new ...  > read more

Low-carb Diet Better Than Low-fat Diet At Improving Metabolic Syndrome (Nov. 16, 2005) — Eating a low carbohydrate diet improves metabolic syndrome and may therefore decrease the risk of developing diabetes and cardiovascular disease associated with it. In an article published today in ...  > read more

Search ScienceDaily

Weight Loss Weapon