Harvard Study Questions U.S. Dietary Guidelines
Quote:
Harvard Study Questions U.S. Dietary Guidelines, Links Starchy Vegetables to Middle-Age Weight Gain
Recent research by Harvard University's nutrition experts linked starchy vegetables to weight gain during middle age, calling the U.S. Dietary Guidelines into question. These guidelines currently promote the consumption of all vegetable types, including starchy ones, per the Harvard Gazette.
A recent study by Yi Wan, a postdoctoral research fellow in nutrition at Harvard’s T.H. Chan School of Public Health, examined the diets of roughly 137,000 people under the age of 65 during a 25-year period. The study suggested that substituting starchy vegetables with whole grains, fruits, and non-starchy vegetables could slow down weight gain as people age.
Starchy vegetables, such as potatoes, peas, and corn, are found to have faster digestion rates, leading to a quick rise in blood sugar levels and triggering body fat storage processes. Whole grains, conversely, can prevent weight gain by slowing digestion and reducing blood sugar spikes. Moreover, whole grains are typically high in fiber, a nutrient known to play a role in weight management, per the Harvard Gazette.
The study questions the U.S. Dietary Guidelines that currently advocate for all types of vegetable consumption. Instead, it suggests focusing more on non-starchy vegetable intake for improved health benefits. In regard to refined carbs, starch, and sugar, it doesn't specify a threshold for weight gain, but advises reducing consumption, specifically of added sugars.
Low-carb diets, commonly hailed for their weight loss benefits, are not exempt from this issue. Yi Wan noted that, while carbohydrates are a primary energy source, a low-carb diet might restrict the intake of essential nutrients found in carbohydrate-rich foods like whole grains, fruits, and vegetables.
The study's dietary recommendations are particularly applicable to individuals with higher BMIs and to women who go through significant weight changes. The approach of menopause, and an associated decrease in estrogen levels, often results in increased fat storage in women, the Harvard Gazette reports.
This study excluded participants with a range of health conditions such as diabetes, cancer, cardiovascular disease, respiratory disease, neurodegenerative disorders, gastric conditions, chronic kidney disease, and systemic lupus at the start. Funded by grants from the National Institutes of Health, Friends of FACES/Kids Connect provided additional support but played no role in the study's design, conduct, analysis, or reporting.
While current guidelines for Americans recommend limiting added sugars and consuming at least half of grains as whole grains, they also advocate for all vegetable types—including "dark green; red and orange; beans, peas, and lentils; starchy; and other"—the findings of this study suggest that a more nuanced approach to vegetable consumption may be required to ensure optimal health and weight management for middle-aged individuals.
|
https://hoodline.com/2023/11/harvar...ge-weight-gain/
Quote:
Waistline growing? Eat more veggies — but not this kind.
Study adds starchy variety to list of culprits contributing to middle-age weight gain
ost know indulging in cookies and cakes, soda, and white bread can accelerate weight gain in middle age. New research suggests adding another culprit to the list: starchy vegetables.
A study published in The BMJ earlier this fall finds that swapping whole grains, fruits, and non-starchy vegetables for refined grains, foods high in added sugar, and starchy vegetables — such as potatoes, peas, and corn — can slow weight gain as we age.
“Starch-rich foods tend to digest faster than fiber-rich foods, causing a rapid increase in blood-sugar levels. This quick increase can trigger metabolic processes that convert these sugars into stored body fat,” said Yi Wan, a postdoctoral research fellow in nutrition at Harvard’s T.H. Chan School of Public Health, and co-author of the study.
She added that favoring whole grains deters weight gain by slowing digestion and blood sugar spikes. “This can help mitigate metabolic processes that promote fat storage. In addition, whole-grain foods are typically rich in fiber, a nutrient widely recognized for its beneficial effects on weight management.”
This is the same reason that low-carb diets — often promoted as beneficial to weight loss — don’t work, Wan explained.
“Carbohydrates are the body’s primary energy source,” she said. “More importantly, maintaining a low-carb diet can also limit the consumption of beneficial nutrients like fiber, vitamins, minerals, and many bioactive compounds found in carbohydrate-rich foods like whole grains, fruits, and vegetables.”
“Our findings raise concern about the current U.S. Dietary Guideline recommendation to increase consumption of all types of vegetables, including starchy vegetables.”
Wan, along with other Harvard nutrition researchers and a New York University neurologist, looked at the diets of nearly 137,000 men and women under the age of 65 using data from more than 25 years through the Nurses’ Health Study I and II and the Health Professionals Follow-Up Study.
Notably, the study contradicts U.S. Dietary Guidelines.
“Our findings for starchy vegetables raise concern about the current U.S. Dietary Guideline recommendation to increase consumption of all types of vegetables, including starchy vegetables,” she said. “We recommend a heightened focus on increasing the intake of non-starchy vegetables.”
While the current guidelines for Americans recommend limiting added sugars, they also recommend that “at least half” of grains consumed should be whole grains while all vegetable types are promoted — “dark green; red and orange; beans, peas, and lentils; starchy; and other.”
The study’s dietary recommendations are particularly impactful on people who already have a higher BMI, and on women, Wan said.
“The susceptibility to weight change for women could be related to the menopausal and hormonal status,” she said. “Most women in our study reached menopause, leading to decreased estrogen levels and causing an increase in fat storage.”
As to whether any amount of refined carbs, starch, or sugar are appropriate in a healthy diet, Wan said there is no specific threshold that leads to weight gain.
“We recommend minimizing their consumption, particularly of added sugar,” she said.
Participants in the study were free of diabetes, cancer, cardiovascular disease, respiratory disease, neurodegenerative disorders, gastric conditions, chronic kidney disease, and systemic lupus at the onset.
The study was co-authored by Deirdre K. Tobias, Kristine K. Dennis, Marta Guasch-Ferré, Qi Sun, Eric B. Rimm, Frank B. Hu, David S. Ludwig, and Willett of Harvard and Orrin Devinsky of NYU.
Funding: This study was supported by grants from the National Institutes of Health (UM1 CA186107, U01 CA176726, and U01 CA167552) and by Friends of FACES/Kids Connect. The funders had no role in the design, conduct, analysis, or reporting of this study.
|
https://news.harvard.edu/gazette/st...ge-weight-gain/ |