What’s the hype behind intermittent fasting?



By: Sarah Pittman BS, Graduate Student in Food Science and Human Nutrition at the University of Illinois

Intermittent fasting, also known as intermittent energy restriction, is a diet strategy gaining popularity. People following this diet eat only at certain times of the day, with the hope that restricting caloric intake will result in weight loss. There are 3 types of intermittent fasting: periodic fasting, time-restricted feeding, and alternate-day fasting.

Periodic fasting/whole day fasting:

  • Includes whole-day fasting or energy restriction
  • 1 or 2 fasting days per week and normal eating patterns the other days
  • May eat up to 500-600 calories on fasting days (25% of regular daily caloric intake)

Time-restricted feeding:

  • Eat only during a certain number of hours per day
  • Fasting for 16 hours and eating for 8 hours is an example of the 16:8 diet

Alternate-day fasting:

  • The strictest form of intermittent fasting, this pattern alternates between fasting and feast days (normal intake)
  • 2 categories:
    • Complete alternate-day fasting: no calories are consumed on fasting days
    • Modified alternate-day fasting: allows 500-600 calories on fasting days

What does the research say?

  • There is some limited research that the diet produces weight loss
  • Initial human studies that compared alternate-day fasting to eating less every day showed both works equally for weight loss
  • Most studies have been limited to just a few months at a time, so the long term benefits of intermittent fasting are unknown


Therefore, intermittent fasting has not yet proven to be a research-based, sustainable weight loss strategy. While the data does not support this as a long-term weight loss plan, time-restricted eating may be beneficial for individuals who have trouble curbing late-night snacking.



Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. American Journal of Clinical Nutrition, January 2005. Link: http://ajcn.nutrition.org/content/81/1/69.full

Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial. JAMA Internal Medicine, May 2017. Link: http://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2623528

Monique Tello M. Intermittent fasting: Surprising update – Harvard Health Blog. Harvard Health Blog. Published 2019. Accessed December 2, 2019. Link: https://www.health.harvard.edu/blog/intermittent-fasting-surprising-update-2018062914156

Publishing H. Any benefits to intermittent fasting diets? – Harvard Health. Harvard Health. Published 2019. Accessed December 2, 2019. Link: https://www.health.harvard.edu/diet-and-weight-loss/any-benefits-to-intermittent-fasting-diets


Performance Nutrition Considerations for Service Members and Veterans

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Join the MFLN Nutrition & Wellness team and former Army Dietitian Kimberly Feeney, MS, RD, CSSD for this sports nutrition webinar Performance Nutrition Considerations for Service Members and Veterans. Learn how to assess energy needs, macronutrient needs and timing, fluid needs, supplements, and fad diets affecting athletes. Questions? Contact us at MilFamLN@gmail.com.

Learning Objectives

Following the webinar, participants will be able to:

·     Accurately assess energy and nutrient needs and provide a nutrition prescription based on physical activity level.

·     Identify potential benefits and risks of popular dietary trends in athletes.

·     Objectively evaluate dietary supplements for safety and effectiveness.

1.0 CPEU approved for Registered Dietitians


Kimberly Feeney, MS, RD, CSSD

Experienced Performance Dietitian
Tactical Performance Dietitian, United States Air Force
Prior Army, currently Air Force civilian

How to Connect

You may connect via the APAN Connect system or YouTube Live. For tech support for either system, email us at milfamln@gmail.com. The recording of this webinar will be posted a couple days after the live session.

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Event Materials

Slides: Performance Nutrition Considerations for Service Members and Veterans .pdf