Study: This Hormone May Halt Metabolism When The Body's In Overdrive

We've heard it all before–staying active can be a surefire way to ramp up your metabolism. But the relationship between the amount of activity you do and how it truly affects your metabolism can sometimes feel a bit fuzzy. Thanks to a new study out of the University of Michigan Life Sciences Institute, this relationship is a bit more clear.

Researchers discovered a hormone secreted by the liver called tsukushi, or TSK for short, drastically slows the metabolism of mice when their bodies are actively expending energy. For example, when the mice were in a cold environment, their bodies worked to produce heat, causing TSK levels to rapidly increase.

After observing the elevation of TSK in these high-energy states, the researchers had a hunch that the removal of TSK would cause the mice to burn significantly more calories, which, in fact, it did. In brief periods without food, the mice with TSK held on to their weight, while the mice without TSK rapidly lost weight.

In a separate facet of the study, the mice were overfed a high-fat diet in an effort to gain weight. Those without TSK gained significantly less weight than those with TSK. Additionally, non-TSK mice had lower levels of fat mass on their liver (an unsurprising hallmark of fatty liver disease, yet another affliction associated with obesity and diabetes).

So how could this be important for humans? For starters, metabolic disorders—like diabetes, metabolic syndrome, or insulin resistance, for example—can wreak havoc on your health and lead to a lifetime of symptom management. They can also contribute to weight gain and obesity, which currently affects 2.1 billion people across the globe. Understanding more about their root causes could lead to more effective treatment solutions.

While sparking interest in metabolic disorders, this study also highlights the important role the liver plays in your overall health. Simply put, your liver is the body's switchboard1 to decide what should be flushed away as a toxin and what should be absorbed as a nutrient, so proper liver functioning is key to detox your body and ultimately burn fat. With metabolic disorders, the liver's abilities to balance blood sugar and break down carbohydrates are compromised.

While this study has broad implications for understanding metabolic health, there's still plenty to do on the future research front. According to Emily Kagey, a representative from the University of Michigan, the researchers plan on specifically looking at the relationship between TSK and thermogenic fat, or "brown fat," which creates heat and burns calories when used for energy2 in the body.