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Are All Carbs Bad for You?
Carbohydrate foods get a bad rap, but the healthy ones are an important part of your diet
James Yates
Is there really such a thing as good carbs and bad carbs? And what are carbohydrates, anyway?
Let’s start with what carbohydrates actually are. Think of your body as an engine. Protein is what builds and repairs that engine, which includes your muscles, organs and tissues. Carbohydrates are the fuel that make it run. They are one of three macronutrients, along with protein and fat, and are the body’s preferred source of energy, especially for the brain and nervous system. So by definition, carbohydrates are not bad; they’re necessary.
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That said, and this is where confusion creeps in, not all carbohydrates behave the same way in our body. There really are good carbs and bad carbs, and the difference has far more to do with how the carbs are processed than with the carbs themselves.
Bad carbs are usually highly processed. These are foods where fiber and nutrients are stripped away and replaced with refined starches and added sugars. Think sugary sodas, pastries, white bread, standard white pasta, sweetened coffee drinks and many packaged snacks. My unofficial rule of thumb is this: If it needs unwrapping, it’s probably not doing your body any favors. For instance, plastic-wrapped pastries are rarely gifts to your metabolism or your brain.
Good carbs, on the other hand, tend to look like food in its natural state. Vegetables, fruits, beans, lentils, whole grains, nuts and seeds all contain carbohydrates, and they come bundled with fiber, vitamins, minerals and resistant starch. This is the kind of starch that feeds “good” gut bacteria. Fiber is particularly important since it slows digestion, steadies blood sugar, supports gut health and helps you feel fuller, longer.
Why does this matter more as we age? Because most of us become more insulin-resistant. Your doctor may notice your blood sugar creeping up and will talk to you about hemoglobin A1C, which is a measure of average blood sugar over several months. Refined carbohydrates raise blood sugar quickly, forcing your body to pump out more insulin. Over time, that pattern promotes inflammation and increases the risk of diabetes, weight gain and heart disease.
Research backs this up. Researchers on one large study followed older adults for 15 years and found that a higher intake of simple, so-called “bad” carbohydrates was linked to a greater risk of physical frailty, while complex carbohydrates were not associated with this risk.
Your gut plays a starring role here as well. Clinical data show that diets high in refined carbohydrates negatively affect the gut microbiome and increase inflammatory markers, compared with diets rich in unrefined carbohydrates. When you inflame the gut, you don’t just feel physically worse, your mental well-being can suffer, too.
Highly processed carbs are bad for your brain as well. One 2024 study published in Neurology found that older adults who ate high amounts of ultraprocessed foods had a greater risk for stroke and cognitive decline.
Carbs get blamed for weight gain, too, but again, it’s the type that matters. Empty refined carbs are easy to overeat and hard to efficiently metabolize. Whole-food carbs, rich in fiber, help regulate appetite and provide steady energy. Cut carbs from your diet too aggressively, and folks often experience fatigue, headaches, poor concentration, constipation and nutrient deficiencies.
More from Dr. Adam
What should you actually eat? Keep it simple. Build meals around minimally processed food. Fill half your plate with fiber-rich vegetables, add a quarter plate of lean protein, and include a sensible portion of whole-food carbs like beans, baked or boiled potatoes with the skin, brown rice, whole oats and fresh fruit.
Food should nourish you, not confuse you or make you feel anxious. Carbohydrates have been feeding humans for thousands of years. When you focus on quality and balance instead of restriction, carbohydrates can take their rightful place — not as something to fear, but as an essential part of eating well and aging wisely.
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