August 29, 2011
Foods rich in protein, dairy products help dieters preserve muscle and lose belly fat: study
Hamilton, Ont. August 29, 2011—New research suggests a higher-protein, lower-carbohydrate energy-restricted diet has a major positive impact on body composition, trimming belly fat and increasing lean muscle, particularly when the proteins come from dairy products.
The study, published in the September issue of the Journal of Nutrition, compared three groups of overweight
and obese, but otherwise healthy, premenopausal women. Each consumed either low, medium or high
amounts of dairy foods coupled with higher or lower amounts of protein and carbohydrates.
The women exercised seven days per week for four months, a routine that included five days of aerobic
exercise and two days of circuit weightlifting.
According to the researchers, there were identical total weight losses among the groups, but the higher-protein,
high-dairy group experienced greater whole-body fat and abdomen fat losses, greater lean mass gains and
greater increases in strength.
All the tissue the women lost was fat, which has profound implications for longer-term health, say the
researchers.
“One hundred per cent of the weight lost in the higher-protein, high-dairy group was fat. And the participants
gained muscle mass, which is a major change in body composition,” says Andrea Josse, lead author of the
study and a graduate student in the Department of Kinesiology at McMaster University. “The preservation or
even gain of muscle is very important for maintaining metabolic rate and preventing weight regain, which can be
major problem for many seeking to lose weight.”
Researchers found the lower-protein, low-dairy group lost about a pound and half of muscle, whereas the
lower-protein, medium dairy group lost almost no muscle. In marked contrast, the higher-protein, high-dairy
group actually gained a pound and half of muscle, representing a three-pound difference between the low- and
high-dairy groups.
On top of the muscle mass differences, the higher-protein, high-dairy group lost twice as much belly fat as the
lower-protein, low-dairy group.“Fat in the abdomen is thought to be especially bad for cardiovascular and metabolic health, and it
seems—according to what we found in this study—increasing calcium and protein in the diet may help to further
promote loss of fat from the worst storage area in the body,” says Josse.
“A very important point is that these changes were not captured by simple measures of body weight or body
mass index, which are the most commonly used measures of dietary ‘success,’” adds Stuart Phillips, a
professor in the Department of Kinesiology. “These women also got fitter and stronger, which greatly reduces
their risk of disease.”
The I.D.E.A.L. (Improving Diet Exercise and Lifestyle) for Women study was funded by Dairy Farmers of
Canada, the US Dairy Research Institute and Canadian Institutes of Health Research. Agropur Incorporated
provided the dairy products used in the study.
Attention editors: Video clips of Stuart Phillips and Andrea Josse discussing the findings can be
found at: http://www.youtube.com/watch?v=G4B-35-lwCc
A copy of the study can be found on the Journal of Nutrition’s website at:
http://jn.nutrition.org/content/141/9/1626.full
McMaster University, one of four Canadian universities listed among the Top 100 universities in the world, is
renowned for its innovation in both learning and discovery. It has a student population of 23,000, and more than
150,000 alumni in 128 countries.
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For more information, please contact:
Stuart Phillips
Professor, Department of Kinesiology
McMaster University
905-525-9140, ext. 24465
phillis@mcmaster.ca
Michelle Donovan
Public Relations Manager
McMaster University
905-525-9140, ext. 22869
donovam@mcmaster.ca
Wade Hemsworth
Public Relations Manager
McMaster University
905-525-9140, ext. 27988
hemswor@mcmaster.ca