Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New data validate the low-glycemic diet

27.08.2004


A carefully controlled animal study provides clear evidence that a low-glycemic-index (low-GI) diet – one whose carbohydrates are low in sugar or release sugar slowly – can lead to weight loss, reduced body fat, and reduction in risk factors for diabetes and cardiovascular disease.

"The study findings should give impetus to large-scale trials of low-GI diets in humans," says senior author David Ludwig, MD, PhD, director of the Optimal Weight for Life (OWL) obesity program at Children’s Hospital Boston. His group’s findings appear in the August 28th issue of The Lancet.

Many studies, including small studies in humans, have suggested that low-GI diets are beneficial, but due to study design, the observed benefits could have come from other aspects of the subjects’ diets, such as fiber or overall caloric intake. For this reason, no major health agency or professional association references glycemic index in their dietary guidelines, Ludwig says.



In the current study, rats were fed tightly controlled diets with identical nutrients, except for the type of starch. Both diets were 69 percent carbohydrates, but 11 rats were randomly assigned to a high-GI starch and 10 to a low-GI starch. Food portions were controlled to maintain the same average body weight in the two groups.

At follow-up, the high-GI group had 71 percent more body fat and 8 percent less lean body mass than the low-GI group, despite very similar body weights. The fat in the high-GI group was concentrated in the trunk area, conferring "the apple shape as opposed to the pear shape," Ludwig says. (Having an apple shape is a known risk factor for cardiovascular disease in humans.)

The high-GI group also had significantly greater increases in blood glucose and insulin levels on an oral glucose tolerance test, and far more abnormalities in the pancreatic islet cells that make insulin, all changes that occur in diabetes. Finally, the high-GI group had blood triglyceride levels nearly three times that of the low-GI group, a risk factor for cardiovascular disease.

In a further experiment, rats were randomly assigned to one of the two diets, and, at week 7, were crossed over to the alternate diet for another 3 weeks. Rats that switched from a low to high GI diet showed greater increases in blood glucose and insulin than rats that were switched from high to low GI. Finally, 24 mice were randomly assigned to the low- or hi-GI diet. At week 9, the high-GI group had 93 percent more body fat than mice on the low-GI diet.

"What the study shows is that glycemic index is an independent factor that can have dramatic effects on the major chronic diseases plaguing developed nations – obesity, diabetes, and heart disease," says Ludwig. "This is the first study with hard endpoints that can definitively identify glycemic index as the active dietary factor."

Unlike the popular Atkins diet, which seeks to minimize carbohydrate intake, the low-GI diet makes distinctions among carbs. It avoids high glycemic-index foods, such as white bread, refined breakfast cereals, and concentrated sugars, which are rapidly digested and raise blood glucose and insulin to high levels. Instead, it emphasizes carbohydrates that release sugar more slowly, including whole grains, most fruits, vegetables, nuts, and legumes.

"The Atkins diet tries to get rid of all carbohydrates, which we think is excessively restrictive," says Ludwig. "You don’t have to go to this extreme if you pay attention to the glycemic index and choose low-GI carbs."

Bess Andrews | EurekAlert!
Further information:
http://www.harvard.edu
http://www.childrenshospital.org

More articles from Materials Sciences:

nachricht New design improves performance of flexible wearable electronics
23.06.2017 | North Carolina State University

nachricht Plant inspiration could lead to flexible electronics
22.06.2017 | American Chemical Society

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Touch Displays WAY-AX and WAY-DX by WayCon

27.06.2017 | Power and Electrical Engineering

Drones that drive

27.06.2017 | Information Technology

Ultra-compact phase modulators based on graphene plasmons

27.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>