Intermittent Fasting: When it Comes to Your Health, Timing Matters

The University of Kentucky Public Relations & Strategic Communications Office provides a weekly health column available for use and reprint by news media. This week's column is by Alex Keeble, doctoral student in the UK Center for Muscle Biology; Jean Fry, registered dietitian and assistant professor in the UK College of Health Sciences Department of Athletic Training and Clinical Nutrition; and Julie Pendergast, assistant professor studying chronobiology in the UK College of Arts and Sciences.

LEXINGTON, Ky. (March 1, 2021) — It’s well known that the type of foods eaten impacts health. Research shows that a healthful diet is based on whole plant foods, like vegetables, fruits, whole grains and legumes. Healthful diets also limit trans fats, alcohol, processed grains, and sugary foods and beverages. Eating this way lowers the risk of cancer, diabetes, heart disease, and many other conditions. While studies show the health benefits of a high-quality diet, research also supports a role for timing, too.

Recently, scientists have studied a strategy called time-restricted feeding. Using this approach, all daily eating is contained within a specific time window. For example, a recent study from the University of California-San Diego showed that when participants with metabolic disease reduced their eating window from more than 14 hours to 10 hours a day, without tracking calories, blood sugar was reduced.

Clinical studies have also shown that time-restricted feeding causes weight loss and improves “bad” LDL cholesterol and blood pressure. A study in fruit flies also showed that time-restricted feeding increases longevity. Time-restricted feeding has the potential to improve overall health and longevity.

Other research shows that your body’s natural circadian (timing) rhythms also affect health. For example, some people naturally are early risers and others like the nighttime. Forcing night owls to do things early in the morning and vice versa can have harmful effects on health. Interrupting natural rhythms can affect metabolism, hunger, and behavior, leading to negative health outcomes like increased risk of obesity and cancer.

Early evidence supports that lifestyle timing is important, and suggests that limiting eating to an approximately 8-10 hour window may promote better health. Before making big changes to your eating or lifestyle habits, it’s important to consider how changes will fit into your daily routine in the long-term. Eating has cultural and social importance. Further, there is little known about how time-restricted feeding affects metabolically healthy or physically active people.

It’s also critical to ensure your information comes from the right place. A lot of advice given on social media platforms may not be evidence-based, so consultation with your physician and a registered dietitian is important. Incorrect use of a time-restricted diet could promote an unhealthy relationship with food or disordered eating patterns.

All that said, remember this article the next time you’re tempted to delay bedtime for a Netflix binge and late-night snacks – timing matters.