Low-Carb Diets Could Sabotage Healthy Aging

Posted by

On May 17, 2025

If you’re avoiding carbs in an effort to improve your diet, you may want to reconsider. A new study found that women who ate more carbohydrates — especially the unrefined kind in whole grains, fruits, vegetables, and beans — significantly improved their odds of making it to age 70 without chronic diseases, memory loss, physical decline, or depression.

However, when the researchers looked specifically at women with higher intakes of refined carbohydrates — the kind in white bread, pastries, and processed snacks — they saw that benefit disappear.

“We’ve all heard that different carbohydrates can affect health differently, whether for weight, energy, or blood sugar levels. But rather than just look at the immediate effects of these macronutrients, we wanted to understand what they might mean for good health 30 years later,” says lead author Andres Ardisson Korat, DSc, a scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston.

The study defined healthy aging as:

Living to at least 70 years old
Not having one of 11 major chronic illnesses like heart disease, diabetes, or cancer
Staying mentally sharp with no memory issues
Maintaining physical ability, including the ability to engage in moderate activities like walking a few blocks
Having good mental health as measured by standardized depression scale for older adults

Key Study Findings

The research followed over 47,000 women from the long-running Nurses’ Health Study, tracking their diet starting in midlife (around age 48) and their health into older age (up to their nineties).

At the end of the study, only 8 percent of the women met the criteria for healthy aging.

Key findings included:

Women who ate more fiber, more carbs of any type, and more high-quality carbs had between a 6 to 37 percent greater likelihood of healthy aging and better mental and physical health.
Eating more highly processed carbs was linked to a 13 percent lower chance of healthy aging.
A higher glycemic index and carb-to-fiber ratio was also linked to lower odds of healthy aging.

How the Study Was Conducted

Based on questionnaire responses, researchers tabulated the following dietary intakes for participants:

Total carbs
Refined carbs from processed foods
High-quality (unrefined) carbs from whole grains, fruits, vegetables, and legumes,
Dietary fiber

Researchers also used the questionnaires to calculate the glycemic index and glycemic load of these carbohydrates.

Glycemic index is a measure from 0 to 100 of how a carb-containing food raises blood sugar levels. Generally speaking, highly processed foods have a higher glycemic index, and foods high in fiber or fat have lower indexes.

Glycemic load uses the glycemic index but also factors in the total carbs to help estimate how quickly a food causes blood sugar to rise and how much blood sugar levels will rise in total after eating.

How Can Healthy Carbs Help You Age Better?

It’s likely that quality carbs helped with healthier aging for a few reasons, says Nathan Wood, MD, a chef and the director of the culinary medicine program at the Yale School of Medicine in New Haven, Connecticut. Dr. Wood was not involved in the study.

Fiber

“Fiber is an extremely beneficial component of our diets. It plays an important role in digestive health and feeds our gut microbiome. We are learning more and more about how the health of the microbes in our gut is connected to all sorts of other positive health outcomes — from mental health to heart health to preventing diabetes,” says Wood.

“Fiber intake may decrease levels of markers of inflammation, and this may improve biological pathways involved in aging,” says Dr. Korat.

Fiber also prevents weight gain and its associated complications, he says. “This is because fiber takes up a lot of room in our digestive tract, but our body doesn’t absorb it. It makes us feel full when we eat it, but it doesn’t give our body any energy [calories],” says Wood.

Antioxidants

Another important aspect to consider is that whole grains, fruits, vegetables, and beans (like all plants) contain antioxidants, says Wood.

“Antioxidants help to combat inflammation. In this way, they can protect against cancer, diabetes, heart disease, fatty liver disease, and even signs of aging,” he says.

Why You Shouldn’t Be Afraid of Carbs

“Many people fear carbohydrates, but they are an essential component of the human diet,” says Wood.

It’s interesting that consuming more carbohydrates overall was associated with improved aging, he says.

“It’s likely the case that these carbohydrates came from more healthy sources. In addition, this could mean that these participants who were consuming more carbohydrates were consuming less fat,” says Wood.

Although fat is also a necessary component of the human diet, many of us eat too much of it, he says.

“Even more important is the type of fat we consume. Saturated fat, which is solid at room temperature (think beef tallow, butter, and coconut oil), increases our LDL or ‘bad’ cholesterol. Higher levels of LDL cholesterol are connected to a higher risk for heart disease and strokes. That’s why swapping out saturated fat for carbohydrates would likely lead to improved aging,” says Wood.

Would the Findings Apply to Men and People of Color?

The study only included women and most of them were white. Would eating more quality carbs help men and people of different races and ethnicities with healthy aging?

“Although this study included only women, it is very reasonable to think that these results could be extrapolated to men, as well,” says Wood.

Because there were very few Black or Asian participants, as well as participants of other races, more research would be needed to see if these results could apply to non-white populations — although it’s likely that they would see the same benefits, he says.