Heidi Pak

Postdoctoral Fellows Grant, Univ. of Texas Southwestern Medical Center

Heidi Pak says her grandmother first spurred her interest in the metabolism of aging.

“She always said ‘What’s the point of living a long time if everything hurts?’” Dr. Pak laughed. “Luckily she’s still alive and kicking, but it got me thinking as our health span hasn’t been keeping up with our longer life spans.”

In one of her first studies at the University of Wisconsin – Madison, she analyzed whether adding back branched-chain amino acid would decrease the effect of a calorie-restricted diet. Ultimately, she found no correlation, but the work took her in a new direction.

Now a postdoctoral fellow in Joe Takahashi’s lab at UT Southwestern, her research explores the interplay between eating patterns, calorie restriction and circadian rhythms on metabolism.

“I’ve found some interesting results in mice that eat in a scheduled manner – I call them “habitual eaters” – versus “sporadic eaters” which eat at random times of the day with the same calorie intake,” she said. “While body composition of the two groups did not differ much, energy expenditure followed a very circadian pattern, and more interestingly, respiratory exchange ratio (values which tell us which fuel source the metabolism is utilizing for its primary energy source) followed the pattern of food intake with the sporadic eaters not being able to switch between fuel sources as efficiently as the habitual eaters.”

Her goal is to test the hypothesis that the mice retain a metabolic memory of when food is coming, enabling their bodies to switch back and forth efficiently. She is evaluating if you need a 24-hour window aligned to the body’s circadian rhythm to reap the most benefits of calorie restriction for healthy aging.

“I hope to better understand how feeding pattern affects metabolism and how metabolism anticipates nutrients,” she said.

Dr. Pak was named a 2023 Welch Postdoctoral Fellow of the Life Sciences Research Foundation awardee and hopes to pursue a career in academia.

“I am so grateful to Welch for its support,” she said. “The Foundation is an amazing asset for research in Texas.”