View More 2023, Scientific Sessions, Session Coverage

Studies examine impact of meal timing, exercise, and circadian rhythm on metabolic health


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3 minutes

Food intake and exercise play significant roles in metabolic health.

Kylie Kavanagh, DVM, MS, MPH
Kylie Kavanagh, DVM, MS, MPH

During the session It’s About Time—Eating and Exercising in Metabolic Health, Kylie Kavanagh, DVM, MS, MPH, Professor of Pathology – Comparative Medicine at Wake Forest School of Medicine, discussed how time-restricted feeding (TRF) improves cardiometabolic profiles in primates other than humans.

“Human behavior can really get us into trouble and confound the way we interpret results from behavioral interventions,” she said.

TRF is a form of intermittent fasting, and the key marker for Dr. Kavanagh’s study was an increase in high-density lipoprotein (HDL), or “good,” cholesterol. Dr. Kavanagh studied adult and geriatric nonhuman primates for 12 months on a Western diet that included high-fructose corn syrup and simple sugars. Some primates had 24-hour access to food, and some were on early TRF (eTRF) with access to food only from 6 a.m.-2 p.m.

The study found that in all subjects—even in geriatric primates who already had deficient cholesterol efflux capacity (CEC)—long-term exposure to TRF improved the CEC in adult and geriatric populations. It also found that HDL particles became larger and more apolipoprotein (ApPO) A1-rich with eTRF. Triglyceride levels also decreased.

“Geriatrics can’t have HDL function like they should [because of their age], and this particular intervention really did fix it, for adults and for geriatrics, which are the bulk of our patients,” Dr. Kavanagh said.

Ultimately, eTRF may be a strategy for the improvement of cardiovascular risk in adult and senior populations, she concluded.

Aalim M. Weljie, PhD
Aalim M. Weljie, PhD

Aalim M. Weljie, PhD, Associate Professor of Systems Pharmacology and Translational Therapeutics at the University of Pennsylvania Perelman School of Medicine, discussed circadian rhythm and metabolism.

Organisms have evolved with the cycles of light and dark, and every tissue in the human body has its own clock that is trained and organized through the suprachiasmatic nucleus, a “master regulator” in the brain. The core clock and metabolism are connected at a molecular level through transcriptional factors, nuclear receptors, and post-translational modifications, he explained.

Glucose metabolism is time-of-day dependent, and Dr. Weljie presented data that indicate the mechanism responsible for reduced glucose tolerance later in the day resides in the peripheral tissues. For someone with type 2 diabetes, the ability to dispose of a glucose load is drastically decreased.

Dr. Weljie presented results from a circadian study that used fruit flies as a model organism, in part because there are commonalities in the core clock between mammals and the flies. The study used isotope tracers to provide mechanistic insights.

Researchers injected the flies with glucose to observe the effect after one hour on the pentose phosphate pathway, the glycolysis pathway, and the tricarboxylic acid cycle (TCA) cycle.

“Early in the day, the fly is able to metabolize the glucose into these different pathways more broadly than it can later on in the day,” he said. “I think this is important and harkens back to the translation relevance of this.”

Lisa S. Chow, MD, MS, Professor of Medicine in the Division of Diabetes, Endocrinology, and Metabolism at the University of Minnesota, discussed time-restricted eating and its role in weight loss and metabolic health.