In the ongoing quest for healthier diets and the battle against middle-age weight gain, researchers are pointing to a surprising culprit: starchy vegetables. New findings published in The BMJ reveal that making a dietary switch from refined grains, high-sugar foods, and starchy vegetables, such as potatoes, peas, and corn, to whole grains, fruits, and non-starchy vegetables can slow the inevitable weight gain that often accompanies aging.
Yi Wan, a postdoctoral research fellow in nutrition at Harvard’s T.H. Chan School of Public Health and a co-author of the study, explained, “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.”
Wan emphasized that favoring whole grains, in contrast, can deter 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.”
The study’s conclusions challenge the notion that low-carb diets are effective for weight loss. “Carbohydrates are the body’s primary energy source,” Wan stated, adding that such diets may also limit the intake of valuable nutrients like fiber, vitamins, minerals, and bioactive compounds present in carbohydrate-rich foods like whole grains, fruits, and vegetables.
To arrive at these insights, Wan and her team, along with researchers from Harvard and a neurologist from New York University, analyzed the dietary habits of nearly 137,000 individuals under the age of 65. They relied on data spanning over 25 years from the Nurses’ Health Study I and II and the Health Professionals Follow-Up Study.
What’s intriguing is that these findings run counter to current U.S. Dietary Guidelines. Wan noted, “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. We recommend a heightened focus on increasing the intake of non-starchy vegetables.”
While existing guidelines advise Americans to limit added sugars, they also advocate for the consumption of “at least half” whole grains while promoting all types of vegetables, including starchy ones.
The impact of this research is particularly significant for individuals with a higher body mass index (BMI), with women being particularly affected. Wan commented, “The susceptibility to weight change for women could be related to the menopausal and hormonal status. Most women in our study reached menopause, leading to decreased estrogen levels and causing an increase in fat storage.”
As for the question of whether any amount of refined carbs, starch, or sugar is acceptable in a healthy diet, Wan offered this insight: “We recommend minimizing their consumption, particularly of added sugar.”
It’s important to note that the participants in the study were free of various health conditions at the onset, including diabetes, cancer, cardiovascular disease, respiratory disease, neurodegenerative disorders, gastric conditions, chronic kidney disease, and systemic lupus.