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.