Preventing Midlife Weight Gain with Whole Grains and Non-Starchy Vegetables

The kind of carbs you eat can make a difference in middle-aged weight management, a new study finds.

Research published last month in The BMJ found that high-quality carbohydrates promoted less weight gain in people in midlife, while lower-quality carbohydrates promoted more weight gain.

On average, participants of the study gained weight over a 24-year period, but those who got their carbs from sources like fruits, vegetables, and whole grains gained less weight than those who ate more refined carbs like foods with added sugars or sweetened beverages.

The study’s findings could have major implications for public health since most American diets rely on carbohydrates as their primary calorie source.

The Dietary Guidelines for Americans 2020–2025 recommend consuming 45–65% of daily calories from carbs—yet, according to 2019 research, low-quality carbs account for 42% of a typical American diet.

“Most people will get a major percentage of their calories from carbohydrates, so consuming most of these from good sources is important for weight control and risks of serious diseases,” Yi Wan, PhD, lead study author and postdoctoral research fellow at Harvard University’s T.H. Chan School of Public Health, told Health.

Here’s how carb quality can impact middle-aged weight management, and how experts recommend people shape their diet around high-quality, nutrient-dense carbohydrates.

Experts have known for some time that type of carbohydrates can affect weight management. However, the new study is unique in its long follow-up period, scope, and focus on people in middle age.

Using data from the Nurses’ Health Study, Nurses’ Health Study II, and the Health Professionals Follow-Up Study, researchers assessed the diets of over 113,000 women and over 22,000 men who, on average, ranged from 40–65 years old. Subjects completed self-administered questionnaires about their diets (including carbohydrate intake) every two to four years for a total of 24 years.

As participants aged, some level of weight gain appeared to be inevitable, no matter what type of carbs people primarily ate.

“People in midlife years go through many changes,” explained Steven Batash, MD, FACG, a weight loss specialist and gastroenterologist. “It becomes harder and harder to control the amount of calories consumed, and even small positive calorie balance over a period of time will lead to weight gain.”

Batash noted that less physical activity, hormonal fluctuations in women, and greater affluence can all lead to weight gain in midlife.

Still, the new study found noteworthy differences in weight gain based on the types of carbs study participants consumed regularly.

People whose carb intake included more starch and added sugar tended to gain more weight over time. On the other hand, people who ate carbs that boosted their daily fiber intake gained less weight.

Whole grain foods, fruits, and vegetables were all associated with significantly lower weight gain.

Though the study was quite extensive, Wan noted a few limitations:

However, when the researchers analyzed the data by race, the associations between carbohydrates and weight appeared consistent across different racial groups.

On a chemical level, all carbohydrates are made up of carbon, hydrogen, and oxygen—so why exactly does the “type” of carb you eat matter for weight loss?

The body processes different types of carbs differently, with some promoting weight management better than others. Much of carbs’ impact on weight boils down to how much they fill you up.

“Healthier carbs like whole grains and veggies usually contain more fiber, more nutrients, and fewer calories than high-glycemic foods,” said Batash. “Fiber keeps you full longer, and since vegetables usually contain fewer calories than high-glycemic carbs, it is easier to maintain a negative calorie balance.”  

The effect of various carbs on blood sugar may also be part of the weight loss equation.

“Some carbs [like refined sugars] are quickly absorbed, causing a rapid increase in blood sugar levels,” Wan said. “This can trigger metabolic processes that store these sugars as body fat.”

Unlike high-fiber foods (such as whole wheat bread, beans, and fresh produce), high-glycemic carbs like sodas, candies, or pastries are rapidly absorbed in the bloodstream, leaving you hungry more quickly. Batash said this can create a vicious cycle of overeating.

If certain carbs may be more likely to impact weight management, it’s important to understand how to choose the type of carb that’s best for your nutrition goals.

Start with choices high in fiber.

According to the Academy of Nutrition and Dietetics, women should strive for about 25 grams of fiber per day and men should try for about 38 grams per day. Foods like fruits, vegetables, whole grains, beans, legumes, nuts, and seeds all add to this total.

Meanwhile, sugary sodas, refined flour breads and pastas, and white rice are less optimal for weight management. They offer little fiber and can quickly elevate blood sugar.

As you attempt to tweak your carb intake, just know that it doesn’t have to mean totally overhauling your diet. Small changes and swaps can make a difference over time.

Some of Batash’s recommendations include:

With any weight management plan, continuing to enjoy your favorite foods is still an important priority when you’re adjusting types of carbs.

“Go with healthy choices 80% of the time and allow yourself to eat that pasta you love on occasion,” said Batash. “No food should be deemed off limits.”