Choice
of protein- and carbohydrate-rich foods may have big effects on long-term
weight gain
Tufts University, Science
Daily
Making small, consistent changes to the types of protein- and
carbohydrate-rich foods we eat may have a big impact on long-term weight gain,
according to a new study led by researchers at the Friedman School of Nutrition
Science & Policy at Tufts University. The results were published on-line in
the The American Journal of Clinical Nutrition.
Based on more than 16 years of follow-up among 120,000 men and
women from three long-term studies of U.S. health professionals, the authors
first found that diets with a high glycemic load (GL) from eating refined
grains, starches, and sugars were associated with more weight gain. Previous
research has linked GL of the diet, a reflection of how much a food causes a
rise in blood glucose, to chronic diseases like type 2 diabetes but it had not
been established how GL is related to weight-gain over many years.
Next, the authors determined whether changes in GL impacted the relationship between major protein-rich foods and long-term weight gain.
"There is mounting scientific evidence that diets including
less low-quality carbohydrates, such as white breads, potatoes, and sweets, and
higher in protein-rich foods may be more efficient for weight loss," said
first and corresponding author Jessica Smith, Ph.D., a visiting scholar at the
Friedman School and a research fellow at the Harvard T.H. Chan School of Public
Health. "We wanted to know how that might apply to preventing weight gain
in the first place."
Smith and colleagues first looked at the relationship between
changes in protein foods and weight gain during every four-years of follow-up.
Several key results were seen:
- Increasing intakes of red meat and processed meat were most strongly associated with weight gain.
- Increasing intakes of yogurt, seafood, skinless chicken, and nuts were most strongly associated with weight loss -- the more people ate, the less weight they gained.
- Increasing other dairy products, including full-fat cheese, whole milk, and low-fat milk, did not significantly relate to either weight gain or weight loss.
"The fat content of dairy products did not seem to be
important for weight gain," Smith said. "In fact, when people
consumed more low-fat dairy products, they actually increased their consumption
of carbs, which may promote weight gain. This suggests that people compensate,
over years, for the lower calories in low-fat dairy by increasing their carb
intake."
Next, the authors noted several synergistic relationships
between changes in protein-rich foods and changes in GL of the diet. For
example, increasing servings of foods linked to weight gain, like red meat, and
at the same time increasing GL by eating more low quality carbohydrates like
white bread, strengthened the foods' association with weight gain. But
decreasing GL by eating, for example, red meat with vegetables, mitigated some
of that weight gain.
For fish, nuts, and other foods associated with weight loss,
decreasing GL enhanced their weight loss effect, while increasing GL decreased
their weight loss effect. Notably, although other foods like eggs and cheese
were not linked to weight change on average, when servings of these foods were
increased in combination with increased GL, they were linked to weight gain. On
the other hand, when servings of eggs and cheese were increased in combination
with decreased GL, the participants actually lost weight.
"Our study adds to growing new research that counting
calories is not the most effective strategy for long-term weight management and
prevention," said senior author Dariush Mozaffarian, M.D., Dr.P.H., dean
of the Friedman School. "Some foods help prevent weight gain, others make
it worse.
"Most interestingly, the combination of foods seems to make a big difference. Our findings suggest we should not only emphasize specific protein-rich foods like fish, nuts, and yogurt to prevent weight gain, but also focus on avoiding refined grains, starches, and sugars in order to maximize the benefits of these healthful protein-rich foods, create new benefits for other foods like eggs and cheese, and reduce the weight gain associated with meats."
"Most interestingly, the combination of foods seems to make a big difference. Our findings suggest we should not only emphasize specific protein-rich foods like fish, nuts, and yogurt to prevent weight gain, but also focus on avoiding refined grains, starches, and sugars in order to maximize the benefits of these healthful protein-rich foods, create new benefits for other foods like eggs and cheese, and reduce the weight gain associated with meats."
The researchers relied on validated self-reported food
questionnaires from three studies that enrolled doctors, nurses and other
healthcare professionals from across the U.S. Further studies investigating the
relationships of protein and carbohydrate-rich foods to weight management in
the other populations would be useful.
Story Source:
The above story is based on materials provided by Tufts University. Note: Materials may be edited for content and
length.
Journal Reference:
J. D. Smith, T. Hou, D. S. Ludwig, E. B. Rimm, W. Willett, F. B.
Hu, D. Mozaffarian.Changes in intake of protein foods, carbohydrate amount and
quality, and long-term weight change: results from 3 prospective cohorts. American
Journal of Clinical Nutrition, 2015; DOI: 10.3945/ajcn.114.100867
Cite This Page:
Tufts University. "Choice of protein- and carbohydrate-rich
foods may have big effects on long-term weight gain." Science Daily,
9 April 2015. <www.sciencedaily.com/releases/2015/04/150409133206.htm>.
