Physical activity is essential to fighting obesity, and scientists are constantly working to make it more effective and beneficial.
A $450,000 grant from the National Institutes of Health will help 91˛Öżâ Biological Sciences Professor, Dr. Colleen Novak, better understand how the body allocates energy and burns fat.
In her project, “Mechanisms Underlying Contextual Induction of Muscle Thermogenesis,” Novak is studying the biological phenomenon known as thermogenesis — how the body burns caloric energy, turning it into heat. She specifically aims to determine how she can engage muscle thermogenesis so that she can have muscles burning more calories for the same amount of effort.
“Thermogenesis burns energy in general, and hopefully some of that energy will be fat.”
“We are focused on the heat put off by skeletal muscle as a way to dissipate energy,” Novak said. “We’ve found a way to make rats engage muscle thermogenesis, and this grant allows us to study the mechanisms behind that.”
The biological systems and processes in rats are very similar to those in humans, so the rodents are commonly studied as findings have the potential for human applications.
Novak’s research has previously shown that obese rats have lower rates of muscle thermogenesis, burning fewer calories during activity, and not increasing their muscle temperature as much as the lean rats.
“We have to figure that out if we want to be able to hijack the process to replicate the phenomenon in humans somewhere down the line,” Novak said. “Thermogenesis burns energy in general, and hopefully some of that energy will be from fat.”
She said the project will prove the importance and potential of thermogenesis for inducing weight loss, separate muscle from other sources of thermogenesis in animal models, and allow researchers to eventually understand the brain’s role in the process.
“We’ll be testing some ideas on what brain mechanisms are involved in controlling this,” Novak said. “We’ll be able to develop the tools to tap into some existing theories.”
Novak said it is believed the brain communicates with skeletal muscle through the sympathetic nervous system — the part responsible for the “fight-or-flight” response — based on two key observations.
“We know other brain regions are involved in turning on other types of thermogenesis through the sympathetic nervous system, so it logically follows that the brain region we study would use a similar pathway,” Novak said.
More decisive, though, are Novak’s observations of the rats’ responses to certain stimuli.
“The best result comes when we expose them to predator odor,” Novak said.
When she introduces the scent of a ferret — a natural predator to rats — the rats’ leg muscle temperature rises by a full degree Celsius within two minutes, and as much as 1.5 to 2 degrees within 10 to 15 minutes.
In essence, what could lead animals — and eventually humans — to engage skeletal muscle thermogenesis, and burn more calories for the same amount of work, is the reaction to a perceived threat, or at least tricking the body into triggering the corresponding biological response.
Novak said that in the context of weight loss, burning energy less efficiently is good, because it means the body is using more calories.
She likened the phenomenon to an inefficient car engine.
“We think this process changes how muscle cells handle energy, and it can make them less efficient,” she said. “Like an engine, you can tell when it’s not running efficiently, because it will lose power to heat. The energy has to go somewhere.”