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 Freiburg researcher investigate the origins of surface texture
17.02.2020 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht Understanding Metal Ion Release from Hip Implants
17.02.2020 | Max-Planck-Institut für Eisenforschung GmbH

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Freiburg researcher investigate the origins of surface texture

Most natural and artificial surfaces are rough: metals and even glasses that appear smooth to the naked eye can look like jagged mountain ranges under the microscope. There is currently no uniform theory about the origin of this roughness despite it being observed on all scales, from the atomic to the tectonic. Scientists suspect that the rough surface is formed by irreversible plastic deformation that occurs in many processes of mechanical machining of components such as milling.

Prof. Dr. Lars Pastewka from the Simulation group at the Department of Microsystems Engineering at the University of Freiburg and his team have simulated such...

Im Focus: Skyrmions like it hot: Spin structures are controllable even at high temperatures

Investigation of the temperature dependence of the skyrmion Hall effect reveals further insights into possible new data storage devices

The joint research project of Johannes Gutenberg University Mainz (JGU) and the Massachusetts Institute of Technology (MIT) that had previously demonstrated...

Im Focus: Making the internet more energy efficient through systemic optimization

Researchers at Chalmers University of Technology, Sweden, recently completed a 5-year research project looking at how to make fibre optic communications systems more energy efficient. Among their proposals are smart, error-correcting data chip circuits, which they refined to be 10 times less energy consumptive. The project has yielded several scientific articles, in publications including Nature Communications.

Streaming films and music, scrolling through social media, and using cloud-based storage services are everyday activities now.

Im Focus: New synthesis methods enhance 3D chemical space for drug discovery

After helping develop a new approach for organic synthesis -- carbon-hydrogen functionalization -- scientists at Emory University are now showing how this approach may apply to drug discovery. Nature Catalysis published their most recent work -- a streamlined process for making a three-dimensional scaffold of keen interest to the pharmaceutical industry.

"Our tools open up whole new chemical space for potential drug targets," says Huw Davies, Emory professor of organic chemistry and senior author of the paper.

Im Focus: Quantum fluctuations sustain the record superconductor

Superconductivity approaching room temperature may be possible in hydrogen-rich compounds at much lower pressures than previously expected

Reaching room-temperature superconductivity is one of the biggest dreams in physics. Its discovery would bring a technological revolution by providing...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

70th Lindau Nobel Laureate Meeting: Around 70 Laureates set to meet with young scientists from approx. 100 countries

12.02.2020 | Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

 
Latest News

Movement of a liquid droplet generates over 5 volts of electricity

18.02.2020 | Power and Electrical Engineering

Powering the future: Smallest all-digital circuit opens doors to 5 nm next-gen semiconductor

18.02.2020 | Information Technology

Studying electrons, bridging two realms of physics: connecting solids and soft matter

18.02.2020 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>