Carbohydrates are not all the same: some are beneficial and aid in weight loss, while others lead to weight gain and disease development. We looked into the different types of carbohydrates and how they affect health.
A significant study on the impact of carbohydrates on women’s longevity was published in JAMA Network Open in May 2025. Researchers from Tufts University and Harvard Medical School examined the diets of 47,000 women aged 70 to 93. Participants had meticulously completed dietary questionnaires for decades, allowing researchers to correlate the quality of carbohydrates in their diet with their aging process.
The researchers defined “healthy aging” not only as the absence of chronic illnesses but also the maintenance of physical activity, clear thinking, and good mental health. Only 8% of the women met these criteria.
The analysis showed that those who consumed more complex carbohydrates (vegetables, fruits, whole grains, legumes) and fiber during middle age had a 6–37% higher chance of preserving their health in old age. Conversely, an excess of refined carbohydrates (white bread, pastries, polished rice) and starchy items yielded the opposite outcome.
Dietitians have named a product that truly aids weight loss.
What kinds of carbohydrates exist?
They are divided into simple and complex. Simple carbs consist of one sugar molecule (like glucose) or two (sucrose). The body doesn’t need to expend energy or time breaking them down; they are absorbed directly into the bloodstream.
Examples of foods with simple carbohydrates include:
sugary sodas,
sweets,
fruit juices (even natural ones),
honey,
pastries made with refined flour.
Complex carbohydrates are made up of long chains of sugars that break down slowly. They provide the body with energy evenly and over a long period.
Examples include:
whole-grain products (oatmeal, buckwheat, brown rice),
legumes,
vegetables,
fruits,
nuts,
seeds.
Why complex carbohydrates are so beneficial
This benefit stems not only from the nature of these carbohydrates but also from the foods in which they are found. Here are several key beneficial properties of complex carbohydrates and the foods rich in them.
Dietary Fiber
This is a complex carbohydrate present in legumes, vegetables, fruits, and whole grains. It slows down food absorption, promotes a feeling of fullness, and positively affects metabolism. This is particularly important in middle age when metabolism naturally slows down.
Furthermore, fiber reduces the rate at which blood sugar rises and improves cell sensitivity to insulin, thus lowering the risk of type 2 diabetes.
Beneficial foods richest in fiber have been identified.
Vitamins, Minerals, and Phytonutrients
Foods high in complex carbohydrates also supply essential health nutrients, including:
B vitamins (folate, B6, thiamine)—necessary for normal metabolism and nervous system function,
potassium—regulates blood pressure,
magnesium—needed for the heart, blood vessels, and muscles.
Vegetables, fruits, grains, and legumes also contain antioxidants such as carotenoids and flavonoids. These combat inflammation and oxidative stress—processes that speed up aging.
They improve gut function
Complex carbohydrates serve as food for beneficial bacteria, which produce butyrate. This is a short-chain fatty acid that has anti-inflammatory effects.
There is evidence suggesting that people who eat plenty of complex carbohydrates have lower arterial stiffness (an important indicator of cardiovascular health).
Low Glycemic Index (GI)
Most whole foods cause sugar levels to rise gradually rather than spiking. Glucose enters the blood as complex carbohydrates are broken down, which takes time. This way, the body receives sustained energy, and the strain on the pancreas is reduced.
What is the Glycemic Index: how ice cream turned out to be healthier than bread.
Same Calories, Different Effects
Let’s compare whole-grain bread with white bread made from refined flour. The calorie content of these products is roughly the same—250–270 kcal per 100g. However, the effects will differ:
white bread breaks down quickly, and almost all calories are absorbed,
whole-grain bread, due to its high fiber content, will take longer to digest,
whole-grain bread contains significantly more minerals and vitamins.
As mentioned, refined carbohydrates cause spikes in insulin and sugar. Over time, such fluctuations increase the risk of:
obesity,
type 2 diabetes,
cardiovascular diseases,
chronic inflammation,
dementia.
It is often due to simple sugars that carbohydrates get demonized. This gave rise to the popularity of the keto diet and other very low-carbohydrate eating plans. However, with such a diet, a person deprives their body of fiber and other valuable nutrients. The problem isn’t with carbohydrates themselves, but with their quality.
The healthiest types of bread.
The Main Takeaway
The quality of carbohydrates is more important than their quantity. Whole grains, vegetables, fruits, and legumes supply the body with fiber, minerals, and antioxidants. Such a diet slows down aging. Simple carbohydrates have the opposite effect. Therefore, the key strategy for healthy eating is not carbohydrate avoidance, but a sensible selection of their sources.
About the Author
