Metabolomics is the study of metabolism using the latest technology to look directly into cells. Metabolic rate is often measured through oxygen consumption and CO₂ production (indirect calorimetry), but this primarily focuses on aerobic processes and does not provide a complete picture of metabolism. Within metabolism, there are both aerobic and anaerobic energy pathways.
Measuring metabolic rate through oxygen consumption and CO₂ production does not account for anaerobic processes such as glycolysis (glucose breakdown), beta-oxidation of fatty acids, and the creatine phosphate system.
Researchers sometimes try to mitigate this limitation by measuring lactate levels in the blood, which can provide some insight into anaerobic metabolism, particularly in muscles. However, blood lactate levels primarily reflect anaerobic glycolysis and do not fully account for other anaerobic processes involving fatty acids and creatine phosphate. There are formulas to estimate these processes, but they are still approximations.
Metabolomics, on the other hand, looks directly into the cells and is not limited to only aerobic processes or anaerobic lactate production. Instead, it can identify and quantify a wide range of metabolites, which are the intermediates and end products of metabolic reactions. Thus, metabolic rate measurements provide an estimate of energy expenditure but do not directly assess the complex metabolic processes occurring within cells, whereas metabolomics offers a more direct and detailed view of cellular metabolism.
As such, the study published in Nature is within the field of metabolism and uses the latest technology to study metabolism directly. Therefor it constitutes our latest understanding of metabolism during fasting.
Researchers sometimes try to mitigate this limitation by measuring lactate levels in the blood, which can provide some insight into anaerobic metabolism, particularly in muscles. However, blood lactate levels primarily reflect anaerobic glycolysis and do not fully account for other anaerobic processes involving fatty acids and creatine phosphate. There are formulas to estimate these processes, but they are still approximations.
Metabolomics, on the other hand, looks directly into the cells and is not limited to only aerobic processes or anaerobic lactate production. Instead, it can identify and quantify a wide range of metabolites, which are the intermediates and end products of metabolic reactions. Thus, metabolic rate measurements provide an estimate of energy expenditure but do not directly assess the complex metabolic processes occurring within cells, whereas metabolomics offers a more direct and detailed view of cellular metabolism.
As such, the study published in Nature is within the field of metabolism and uses the latest technology to study metabolism directly. Therefor it constitutes our latest understanding of metabolism during fasting.