Intermittent fasting: Using the clock to manage calories

Feb. 4, 2026

By Mary Hightower
University of Arkansas System Division of Agriculture

Fast Facts

(521 words)

Download file photo of Araghi

LITTLE ROCK — Counting hours rather than calories — known as intermittent fasting — may help some people manage weight.

“Intermittent fasting is an eating pattern based on time instead of specific foods,” said Lida Araghi, assistant professor and extension nutrition and foods specialist for the University of Arkansas System Division of Agriculture. “You choose set hours to eat, and you do not eat during the fasting hours.”

Araghi
Lida Araghhi says intermittent fasting can flip the metabolic swtich. (UADA file photo)

Araghi said that intermittent fasting can encourage the body to shift from using stored sugar — blood glucose — to using more fat-based fuel. This action is sometimes called a “metabolic switch,” she said.

“The method of limiting eating hours may help some people eat fewer calories without tracking calories,” Araghi said.

Time-restricted eating using a 14- to 16-hour fasting window is being studied for benefits such as improved insulin sensitivity and reduced inflammation. Fasting can also trigger autophagy, the process by which cells are broken down and recycled to create newer cells, she said.

A common intermittent fasting style is 16:8, fasting for 16 hours and eating during an eight-hour window.

“During the fasting time, water is encouraged,” she said. “Many plans also allow zero-calorie drinks like plain tea or black coffee. If a drink has sugar or calories, it breaks the fast.”

However, a 16-hour fast doesn’t give the faster carte blanche to eat more or just anything.

“Food choices still matter because a smaller eating window does not automatically mean a healthier diet,” Araghi said.

Who benefits from fasting?

Intermittent fasting can benefit people who like a simple structure with clear time rules for a weight management tool they can stick with, she said.

It’s also helpful for people who like to snack late in the evening and “want a way to reduce late-night eating,” Araghi said.

As with any change in diet, there are some caveats. Fasting may not be appropriate for people who:

  • Are pregnant or breastfeeding
  • Have a current or past eating disorder
  • Are under 18 years of age
  • Are at high risk of bone loss or falls
  • Take insulin or certain diabetes medicines, including sulfonylureas, unless a clinician adjusts the plan, because fasting can raise the risk of low blood sugar

Getting started

Araghi offered a simple starter plan for intermittent fasting:

  • Start with a 12-hour overnight fast — finish eating at 7 p.m. and then wait until 7 a.m. to eat breakfast.
  • If the faster is still feeling well after one to two weeks, 14:10 — 14 hours fasting, 10 hours eating — can be attempted.
  • If all is still going well, some people may move to 16:8 — 16 hours fasting, 8 hours eating.

Araghi said fasters should:

  • Drink water regularly during the day.
  • Build meals around protein, fiber-rich foods such as beans, whole grains, vegetables, and fruit, and healthy fats to help you feel full longer.

Some people feel side effects at first, such as hunger, headache, or irritability, especially in the first week or two, she said.

“Stop and get help if you feel faint, confused, or have signs of low blood sugar,” she said.

Learn more about intermittent fasting from the extension fact sheet FSCS135, The Science of Intermittent Fasting.

To learn about extension programs in Arkansas, contact your local Cooperative Extension Service agent or visit uaex.uada.edu. Follow us on Facebook and Instagram. To learn more about the Division of Agriculture, visit uada.edu. To learn more about ag and food research in Arkansas, visit the Arkansas Agricultural Experiment Station at aaes.uada.edu.

About the Division of Agriculture

The University of Arkansas System Division of Agriculture’s mission is to strengthen agriculture, communities, and families by connecting trusted research to the adoption of best practices. Through the Agricultural Experiment Station and the Cooperative Extension Service, the Division of Agriculture conducts research and extension work within the nation’s historic land-grant education system.

The Division of Agriculture is one of 20 entities within the University of Arkansas System. It has offices in all 75 counties in Arkansas and faculty on three campuses.

Pursuant to 7 CFR § 15.3, the University of Arkansas System Division of Agriculture offers all its Extension and Research programs and services (including employment) without regard to race, color, sex, national origin, religion, age, disability, marital or veteran status, genetic information, sexual preference, pregnancy or any other legally protected status, and is an equal opportunity institution.

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Media contact:
Tracy Courage
tcourage@uada.edu