Low-carbohydrate foods are widely available, reflecting the popularity of low-carbohydrate diets for weight management and for reducing blood lipids and postprandial glucose spikes. To better understand the true glycemic impact of these foods, researchers use a measure called equivalent glycemic load (EGL).

New research from the INQUIS team evaluated the EGL of seven low-carbohydrate foods, examining both their glycemic and insulinemic responses. The findings showed that actual EGL values were 20–90% lower than might be expected based on food label information. This discrepancy is likely due to two factors. Firstly, these products had high fat and protein content. Fat and protein are known to reduce glycemic responses by slowing gastric emptying and increasing postprandial insulin levels. Secondly, the products contained carbohydrate ingredients that are not available carbohydrates. In conventional foods (e.g., bread, rice, potato), the amount of available carbohydrate (carbohydrates that raise blood glucose) they contain is reasonably accurately estimated by subtracting the food label value for dietary fiber from the value for carbohydrate. However, low carbohydrate foods often contain carbohydrate ingredients that cannot be converted into blood glucose either because they are not absorbed or because they are not metabolized into glucose and are excreted in the urine. Although these carbohydrates are not available carbohydrates, they are not included in the value for dietary fiber on the food label. Thus, in such products, subtracting the food label value for fiber from that for carbohydrate results in overestimating the amount of available carbohydrate in the product, as we saw here.

Overall, this study demonstrated that EGL is a highly accurate and precise measure, correctly estimating glycemic impact to within 1 gram of net carbohydrate.

As low-carbohydrate products continue to expand in the marketplace, EGL offers an important framework for evaluating their true metabolic effects.

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