Food labels make calorie counts look straightforward. The number listed per serving is calculated from the food’s fat, carbohydrate, and protein content.

In reality, the digestive process is much more complex. As food moves through the body, it interacts with trillions of microbes in the gut that can affect how many calories are ultimately absorbed.

Researchers at Arizona State University have developed a mathematical model called DAMM, short for digestion, absorption, and microbial metabolism, to better capture this process. The model tracks food as it moves through the digestive system, estimating what is absorbed by the body, what reaches the colon, and how gut microbes transform the remaining material into substances that are either absorbed or eliminated.

The researchers say the model could improve understanding of obesity, diabetes, and other metabolic disorders by revealing how different diets influence both the body and the microbial communities living in the colon.

Gut Microbes Change the Calorie Equation
With further development, DAMM could help health care providers create more personalized nutrition plans.

“Digestion is not just a human process—it is a collaboration between our bodies and trillions of microbes living in the gut,” said Professor Rosa Krajmalnik-Brown. “DAMM gives us a powerful new way to quantify how those microbial partners contribute to human health and energy balance and also points at the importance of properly feeding our gut microbes.”