While it has long been used in ancient traditions and major religions, intermittent fasting (IF) is enjoying new popularity among people trying to lose weight. Sometimes called “feast and fast,” IF is an eating pattern with periods of little to no energy intake interspersed with periods of normal energy intake, adhered to on a repeating basis.
Though scientific evidence is still forming, the latest studies show that IF shows promising benefits for the body and brain. It’s important to note, though, that the method involves more than just limiting calories on a regular schedule; it must be personally tailored to be maximally effective.
Interested in exploring IF? Teri Mosey, PhD, a holistic nutrition consultant with 25 years in the health and fitness industry, shares insights into the philosophy and implementation of this approach.
Why Intermittent Fasting?
IF has drawn the attention of the weight loss industry because simply restricting calories continues to show a poor success rate, a high incidence of weight regain and negative biological consequences (Ganesan, Habboush & Sultan 2018).
That’s because there’s more to weight than an energy-calorie equation. Research shows that meal selection, metabolic processes, circadian rhythms, emotional state and sleep patterns contribute to long-term weight management (Eichelmann et al. 2016; Wang et al. 2017).
The IF method includes food selection, timing and frequency manipulation and may involve caloric restriction. These variables lead to changes in eating and sleeping patterns, resulting in positive alterations to metabolic rhythms (Aksungar et al. 2017). The altered biorhythms, in turn, shift inflammatory biomarkers, hormone secretions, microbiome health, cognitive function and metabolic pathways—all of which can potentially extend life span and lengthen health span (Carlson et al. 2007; Mattson, Longo & Harvie 2017).
Getting Started With Intermittent Fasting
If, after consulting with a nutrition professional, you decide to try IF, consider these suggestions:
Choose an IF regimen carefully. Select an approach that you can sustain. Consistency is crucial to reaping benefits.
Change the timing gradually. Rather than shift the timing of your food intake all at once, trim a little time off your eating window, about 30 minutes, each day.
Omit late-night eating. This will help align IF with circadian rhythms.
Time meals to support digestion. Consider going 5 hours between meals or snacks to support the body’s migrating motor complex and to create metabolic flexibility.
Expect some discomfort. There will be a time of imbalance as hunger sensations and hormones adapt. Be prepared to feel hungry, moody and preoccupied with food when first starting.
Be committed. Practice for at least 8 weeks to begin reaping IF’s benefits as part of a preexisting healthy lifestyle.
Is Intermittent Fasting a Good Fit?
Use the following information as a starting point to decide whether intermittent fasting (IF) may work for you. You can also consult with a registered dietitian to get personalized guidance. (See eatright.org to find one.)
Positive indicators. IF may be a good fit for you if you want to
- improve body awareness and hunger/fullness cues;
- explore life without strong food attachments;
- work toward the potential health benefits of the practice; and
- enhance an existing health-supportive lifestyle.
Contraindications. IF is not meant for those who are
- younger than 23 or older than 75;
- pregnant or breastfeeding;
- diagnosed with advanced type 1 diabetes;
- struggling with a chronic sleep disorder;
- challenged with an eating disorder or trying to counteract poor eating habits; or
- predisposed to taking practices, including healthy ones, to an unhealthy extreme.
Aksungar, F.B., et al. 2017. Comparison of intermittent fasting versus caloric restriction in obese subjects: A two year follow-up. The Journal of Nutrition, Health and Aging, 21 (6), 681–85.
Carlson, O., et al. 2007. Impact of reduced meal frequency without caloric restriction on glucose regulation in healthy, normal weight middle-aged men and women. Metabolism, 56 (12), 1729–34.
Eichelmann, F., et al. 2016. Effect of plant-based diets on obesity-related inflammatory profiles: A systematic review and meta-analysis of intervention trials. Obesity Reviews, 17 (11), 1067–79.
Ganesan, K., Habboush, Y., & Sultan, S. 2018. Intermittent fasting: The choice for a healthier lifestyle. Cureus, 10 (7), e2947.
Mattson, M.P., Longo, V.D., & Harvie, M. 2017. Impact of intermittent fasting on health and disease processes. Aging Research Reviews, 39, 46–58.
Wang, Y., et al. 2017. The intestinal microbiota regulates body composition through NFIL3 and the circadian clock. Science, 357 (6354), 912–16.