The research, which compared the results of a high-protein, dairy-intensive diet with a conventional weight-loss diet based on the food-guide pyramid, was published in this month's Journal of Nutrition.
"This is an important finding because many people, especially women in mid-life, are concerned with both obesity and osteoporosis," said Ellen Evans, a U of I associate professor of kinesiology and community health and member of the U of I Division of Nutritional Sciences.
"Furthermore, treating obesity often increases risk for osteoporosis. Many people lose bone mass when they lose weight," she said.
Study co-author Donald Layman, a U of I professor of nutrition, has previously reported that protein-rich weight-loss diets preserve muscle mass, help lower blood sugar and lipids, and improve body composition by targeting weight carried in the abdomen.
In the recent study, Layman's diet prescribed approximately 30 percent of all calories from protein, with an emphasis on lean meats and low-fat dairy products.
The scientists recruited and randomized 130 middle-aged, overweight persons at two sites—the U of I and Pennsylvania State University. Participants then followed either the higher-protein weight-loss diet or a conventional higher-carbohydrate weight-loss diet based on the food-guide pyramid for four months of active weight loss followed by eight months of weight maintenance.
"Essentially we substituted lean meats and low-fat milk, cheese, yogurt, etc., for some of the high-carbohydrate foods in the food-pyramid diet. Participants also ate five servings of vegetables and two to three servings of fruit each day," Evans said.
Bone mineral content and density were measured with DXA scans of the whole body, lumbar spine, and hip at the beginning of the study, at four months, at eight months, and at the end of the 12-month period.
"In the higher-protein group, bone density remained fairly stable, but bone health declined over time in the group that followed the conventional higher-carbohydrate diet. A statistically significant treatment effect favored the higher-protein diet group," said Matthew Thorpe, a medical scholars (MD/PhD) student who works in Evans's lab and was the primary author of the study.
"The combination and/or interaction of dietary protein, calcium from dairy, and the additional vitamin D that fortifies dairy products appears to protect bone health during weight loss," he added.
Because higher-protein diets have been associated with elevated urinary calcium levels, some scientists have feared that these diets cause bone demineralization.
The U of I team measured these levels at the beginning and eight months into the study. Although the researchers did note increased amounts of urinary calcium in the higher-protein group, they attributed the source of the increased calcium to improved intestinal absorption of calcium rather than bone loss.
"Other recent studies using radiolabeled calcium have shown that the higher urinary calcium levels associated with higher-protein diets are not coming from bone as some researchers had believed," Thorpe said.
The U of I scientists will soon begin a similar study contrasting higher-protein, dairy-rich diets with conventional weight-loss diets in older, mildly frail women.
"We'll measure bone and muscle outcomes in the two groups after six months of weight loss. Ultimately we want to know if a higher-protein weight-loss diet that emphasizes lean meats, whey protein, and low-fat dairy consumption can reduce the risk for osteoporosis and muscle loss.
"We also want to learn how these changes in body composition will affect balance, gait, and other measures of physical function in this population known to be at high risk for osteoporosis and physical disability," she said.
Phyllis Picklesimer | EurekAlert!
Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT
Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
05.12.2016 | Power and Electrical Engineering
05.12.2016 | Information Technology
05.12.2016 | Earth Sciences