Carbohydrates: Sugars & Starches

Carbohydrates occur in food as sugars, starches, and fiber. Sugars and starches are broken down and used to provide energy to your cells. Fiber, on the other hand, is fermented and used as food by gut bacteria.

Why Your Body Needs Carbohydrates

Glucose is the primary energy source for most cells, especially the brain and red blood cells, which rely on it almost entirely. To keep a steady supply of glucose in the blood, your body carefully regulates blood sugar levels. This balance, known as homeostasis, is essential because when blood glucose drops too low, cells cannot function properly. On the other hand, if blood glucose rises too high, it can cause damage to cells.

When you eat carbohydrates, the sugars and starches in them are broken down into simple sugars like glucose, fructose, and galactose, which are absorbed into the bloodstream. Fructose and galactose are then processed by the liver. Galactose is mostly converted into glucose, while fructose is turned into compounds that can be used for energy, stored as glycogen, or converted to fat, depending on the body’s energy needs.

As blood glucose levels rise, the pancreas releases insulin, a hormone that helps move glucose from the bloodstream into your cells. If the cells need energy, glucose is used right away. Otherwise, it’s stored as glycogen in the liver and muscles for later use. If there’s still extra glucose, it can be converted into fat and stored in fat tissue.

Between meals, as well as during sleep and exercise, blood glucose levels naturally drop. When this happens, the body takes several steps to restore balance. The brain and nervous system signal hunger to encourage eating. At the same time, the pancreas releases a hormone called glucagon, which signals the liver to break down stored glycogen and release glucose into the bloodstream. It also activates a process called gluconeogenesis, where new glucose is made from amino acids in the liver and kidneys. Together, these actions help raise blood sugar levels back to a normal range.

Your Daily Carbohydrate Needs

Your body can adapt to low-carbohydrate diets by using fat and protein for energy. However, extremely low carbohydrate intake over the long term reduces glycogen stores and can place added physiological stress on the body. Potential concerns include changes in mood, kidney function, and bone health, depending on overall diet quality and individual factors.

On the other hand, diets high in refined carbohydrates and added sugars have been linked to issues like tooth decay, weight gain, elevated triglycerides, and impaired metabolic health.

Best Sources of Carbohydrates

Most carbohydrates are found as starches in grains, legumes, and tubers. Research suggests that starchy foods absorbed more slowly, especially those that are less processed or prepared using traditional methods, may offer health benefits compared to rapidly digested starches. These slowly absorbed starches have a low glycemic index (GI) and reduce the overall glycemic load of the diet.

GI measures how much a carbohydrate raises blood sugar compared to a reference food over two hours. Glycemic load reflects the total blood sugar and insulin response from all carbohydrates eaten. Both dietary GI and glycemic load have predictable effects on blood sugar, insulin, cholesterol, and other markers of metabolic health.

Fruits and dairy contain naturally occurring sugars. While natural sugars are chemically the same as added sugars, they generally come with more nutrients.