Low-carb diet burns more excess liver fat

January 21st, 2009 - 12:34 pm ICT by IANS  

Washington, Jan 21 (IANS) A low-carbohydrate diet burns more excess liver fat than a low-calorie diet, according to a clinical study. These findings could open the way for treating obesity and related conditions like diabetes, insulin resistance and nonalcoholic fatty liver disease (NAFLD), said Jeffrey Browning, assistant professor at the University of Texas (UT) Southwestern Advanced Imaging Research Centre.

“Instead of looking at drugs to combat obesity and the diseases that stem from it, maybe optimising diet can not only manage and treat these diseases, but also prevent them,” said Browning, the study’s lead author.

Although the study was not designed to determine which diet was more effective for losing weight, the average weight loss for the low-calorie dieters was about 2.5 kg after two weeks, while the low-carbohydrate dieters lost about four kg on average.

Glucose, a form of sugar, and fat are both sources of energy that are metabolised in the liver and used as energy in the body. Glucose can be formed from lactate, amino acids or glycerol.

In order to determine how diet affects glucose production and utilisation in the liver, the researchers randomly assigned 14 obese or overweight adults to either a low-carbohydrate or low-calorie diet and monitored seven lean subjects on a regular diet.

After two weeks, researchers used advanced imaging techniques to analyse the different methods, or biochemical pathways, the subjects used to make glucose. “We saw a dramatic change in where and how the liver was producing glucose, depending on diet,” said Browning.

Researchers found that participants on a low-carbohydrate diet produced more glucose from lactate or amino acids than those on a low-calorie diet.

“Understanding how the liver makes glucose under different dietary conditions may help us better regulate metabolic disorders with diet,” Browning said.

The different diets produced other differences in glucose metabolism. For example, people on a low-calorie diet got about 40 percent of their glucose from glycogen, which is comes from ingested carbohydrates and is stored in the liver until the body needs it.

The low-carbohydrate dieters, however, got only 20 percent of their glucose from glycogen. Instead of dipping into their reserve of glycogen, these subjects burned liver fat for energy, said an UT release.

“Energy production is expensive for the liver,” Browning said. “It appears that for the people on a low-carbohydrate diet, in order to meet that expense, their livers have to burn excess fat.”

These findings were published in Hepatology.

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