Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study examines calorie restriction and glycemic load

10.04.2007
The first phase of a caloric restriction study in human subjects at the Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University found evidence suggesting that calorie-restricted diets differing substantially in glycemic load can result in comparable long-term weight loss.

The study, part of the multi-center Comprehensive Assessment of Long-term Effects of Restricting Intake of Energy (CALERIE) trial, funded by the National Institute on Aging, accounted for dietary factors that affect hunger and satiety, used laboratory techniques to measure adherence, and was the first of its kind to provide a complete set of meals and snacks to its participants. Recruitment is currently underway for participation in the second phase of the CALERIE study at Tufts, which will examine the relationship between calorie-restricted diets, aging, and age-related disease.

"Participants in our pilot study achieved and maintained comparable weight loss after one year, regardless of whether they were on a low-glycemic-load or a high-glycemic-load diet," says corresponding author Susan Roberts, PhD, director of the USDA HNRCA's Energy Metabolism Laboratory. "The goal was for both groups to restrict calories by 30 percent and, after one year, both groups had lost an average of 8 percent of their original body weight. We found that the two groups did not differ significantly in their average body fat loss, energy intake, metabolic rate, or reports of hunger and satiety."

The two study diets were carefully matched for factors known to influence food intake during weight-loss efforts, such as palatability, dietary variety, and fiber. "Because there was careful attention to factors that influence hunger and satiety, participants were generally satisfied on a calorie-restricted diet," says Roberts, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts.

Thirty-four overweight but otherwise healthy men and women were assigned randomly to a low-glycemic-load (LG) or high-glycemic-load (HG) diet. At six months, the LG group had lost an average of 10.4 percent body weight, while the HG group had lost an average of 9 percent body weight. By 12 months, participants in both the LG and HG groups had lost an average of 8 percent of their starting body weight.

"Unlike several other long-term studies, which have reported greater weight loss with low GL diets at six months but no differences by 12 months, our data show no significant short-term or long-term differences," notes Sai Das, PhD, scientist at the USDA HNRCA and first author of the study. "However, we did detect a greater tendency for weight and body-fat regain among LG participants. This finding suggests that reduced calorie intake may be harder to sustain on LG diets over time."

The LG diet contained 40 percent carbohydrate, 30 percent fat, and 30 percent protein; while the HG diet contained 60 percent carbohydrate, 20 percent fat, and 20 percent protein. A food's glycemic load is a relative measure of how much carbohydrate is in the food and how quickly that food is converted in the body to blood sugar. Examples of foods provided as part of the LG diet include bean and barley stew, low-fat cottage cheese, and pumpernickel bread. The HG diet included foods like bagels, candied sweet potatoes and shepherd's pie with mashed potatoes.

Both diets were designed to restrict calories by 30 percent, relative to a person's baseline energy requirements, while providing the recommended amounts of vitamins, minerals, and essential fatty acids. All participants attended weekly behavioral support groups and met individually with a dietitian.

To measure objectively actual dietary intakes, the researchers used a laboratory technique involving doubly labeled water. They determined that both groups ate more calories than study foods provided; at six months the HG group averaged a 16 percent calorie-restricted diet and the LG group averaged a 17 percent calorie-restricted diet. Although participants did consume additional calories, the degree of non-adherence was not significantly different between the LG and HG groups when measured at various points throughout the study.

"An important difference between our study and other weight-loss trials is that we did not rely on self-reported intakes," says Das, who is also an assistant professor at the Friedman School. "Underreporting of caloric intake can vary between 5 and 50 percent. By providing the study food for the first six months, we did not have to worry as much about lifestyle factors like shopping and cooking habits interfering with dietary change."

Roberts previously conducted a pilot study showing that a diet's overall glycemic load may be an important determinant of weight loss for people with high levels of insulin secretion, such as people with diabetes. "We have observed that for some groups, glycemic load may impact weight loss. However, in terms of calorie-restricted diets, we see little difference among diets of varying glycemic load when we account for factors that affect dietary adherence."

Siobhan Gallagher | EurekAlert!
Further information:
http://www.tufts.edu

More articles from Studies and Analyses:

nachricht The importance of biodiversity in forests could increase due to climate change
17.11.2017 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>