Which nutrient has the greatest impact on blood glucose levels?

Carbohydrates have the greatest impact on blood glucose levels because they are the primary source of glucose in the diet. When carbohydrates are consumed, they are broken down into simpler sugars, which then enter the bloodstream, causing a rise in blood glucose levels. This is especially true for simple carbohydrates, like those found in candies, sugary drinks, and white bread, which are rapidly digested and can lead to swift increases in blood sugar.

In contrast, protein and fat have a much lower immediate effect on blood glucose. While protein can influence blood sugar levels through gluconeogenesis, a process where the liver converts amino acids into glucose, this effect is slower and less pronounced compared to the impact of carbohydrate intake. Healthy fats, while essential for the diet, do not convert to glucose and therefore do not directly raise blood sugar levels.

Fiber, although a form of carbohydrate, is not digested in the same way as other carbohydrates. Soluble fiber can help regulate blood sugar levels by slowing digestion and absorption of other nutrients, but it does not contribute directly to blood glucose, particularly in the same immediate manner as other carbohydrate sources.

Thus, among the nutrients listed, carbohydrates stand out as the main dietary component that causes significant fluctuations in blood glucose levels.