Have you ever tried intermittent fasting or thought it might be a good idea for you? You are not alone!
You may have heard of someone who has tried it, or you have in the past. Maybe it worked, maybe it didn’t. The important thing to know is whether it is right for YOU.
What is Intermittent Fasting?
First, a quick refresher. Although there are many forms, the most common type of Intermittent fasting is based on eating only within a certain window of time each day, e.g. 8 hours each day, e.g. 10am-6pm, but not outside that window (vs. fasting every day, or every other day).
The science behind this is that your liver stores energy from meals for 12-16 hours, like a tank. It is usually empty at breakfast, then refills gradually each meal and is hopefully full before bed.
For intermittent fasting, the goal is to empty your ‘tank’ (glycogen stores), based on research that this stimulates growth hormone and burns fat. If you only eat for 8 hours and fast for 16, you would ideally accomplish this goal. You would also assume you are eating less calories overall.
Brunch is later in the morning after natural fasting overnight, when you get to eat breakfast and lunch at the same time! This is a common example of the liver tank being empty, since the first meal will re-fill it but then you need more for the day.
What about your health?
The main takeaway is that while it has been shown to have many benefits, it is not right for everyone. When done correctly it can be healthy, since it based on the science behind liver storage. It can also be a natural way to limit calories at night, which can affect metabolism. However, be careful of restricting calories and ‘dieting’, which can have negative effects on your health.
For the positives, it can be particularly helpful in regulating eating patterns, especially at night. One study in mice from 2012 found that when compared to a group that ate at any time and at night, those with normal feeding times had reduced risk of obesity, insulin disruptions, and inflammation. In humans it can also be a good non-pharmacological option for improved health. It can also lower blood pressure and risk for diabetes by increasing fat burning, and can have short-term benefits on glucose metabolism and lipid profile, although results are mixed and more human studies are needed (see article for review).
For the negatives, if you are a frequent dieter and trying to restrict calories, studies show this can cause weight gain and increased risks to health (especially in teens and girls). While weight gain leads to many health risks, simply restricting calories, which is essentially another way of ‘dieting’, can impair muscle quality (see Cava et. al, 2017 and Collins et. al, 2018 for review) and weaken the immune system.
The foods you eat are not all equal in calories, so even with the Weight Watchers method of staying within certain points, you could miss many nutrients you may need to actually burn fat and build muscle. Your metabolism could also get stuck in ‘starvation’ mode, disrupting insulin and other hormones and the gut microbiome.
(Avoid completely if you are under 18, pregnant, or have an eating disorder or blood sugar condition.)
Decide What is Right for You
Timing meals is an important factor in preventing fat storage. Many of us already do not eat three regular, balanced meals, so our bodies could be lacking in nutrients (although meals may not be lacking in calories!). So it is important to eat healthy foods at regular intervals as a first step, and always reach out to a nutritionist or professional before making changes to your diet.
If you are trying to decide if this is a good option for you, keep in mind there are healthier ways of intermittent fasting, and ways that look more like a diet. Remember your health and weight are more dependent on nutrients than calories, so ask yourself these 3 questions first:
- Do I eat 3 balanced meals per day?
- Do I eat my meals at regular times each day (e.g. no more than 4-5 hours between meals)?
- Do I eat meals after 9pm?
If you answered YES to all these questions, and you still want to try intermittent fasting, that may make sense for you depending on your current eating habits.
If you answered NO to any of these questions, it may not be the best solution for you.
Want to learn more about what is and is not good for your health? Join the WellLife Fall Sustainable Solution starting September 20th! Spots are limited and going fast, sign up today! Early bird specials available.
Katy Harris, MSPH, CSCS is a master of Public Health, Certified Strength & Conditioning Specialist, ultimate Frisbee athlete, and owner of the WellLife Health and Fitness Studio in Chapel Hill, North Carolina.
- Antoni, Rona, et al. “Effects of Intermittent Fasting on Glucose and Lipid Metabolism: Proceedings of the Nutrition Society.” Cambridge Core, Cambridge University Press, 16 Jan. 2017, https://www.cambridge.org/core/journals/proceedings-of-the-nutrition-society/article/effects-of-intermittent-fasting-on-glucose-and-lipid-metabolism/8803CC1517F53CEF2BF8BFDC06A816D6.
- Cava, Edda, et al. “Preserving Healthy Muscle during Weight Loss.” OUP Academic, Oxford University Press, 5 May 2017, https://academic.oup.com/advances/article-abstract/8/3/511/4558114.
- Collins, Kelsey H., et al. “Obesity, Metabolic Syndrome, and Musculoskeletal Disease: Common Inflammatory Pathways Suggest a Central Role for Loss of Muscle Integrity.” Frontiers, Frontiers, 1 Jan. 1AD, https://www.frontiersin.org/articles/10.3389/fphys.2018.00112/full.
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- Hatori, Megumi, et al. “Time-Restricted Feeding without Reducing Caloric Intake Prevents Metabolic Diseases in Mice Fed a High-Fat Diet.” Cell Metabolism, Cell Press, 16 May 2012, https://www.sciencedirect.com/science/article/pii/S1550413112001891.
- “Intermittent Fasting: What Is It, and How Does It Work?” Johns Hopkins Medicine, 7 Mar. 2022, https://www.hopkinsmedicine.org/health/wellness-and-prevention/intermittent-fasting-what-is-it-and-how-does-it-work.
- Malinowski, Bartosz, et al. “Intermittent Fasting in Cardiovascular Disorders-an Overview.” MDPI, Multidisciplinary Digital Publishing Institute, 20 Mar. 2019, https://www.mdpi.com/431602.
- Maslowski, Kendle M, and Charles R Mackay. “Diet, Gut Microbiota and Immune Responses.” Nature News, Nature Publishing Group, 17 Dec. 2010, https://www.nature.com/articles/ni0111-5?message-global=remove&page=4amp%2F.
- Pathways from Dieting to Weight Regain, to … – Wiley Online Library. https://onlinelibrary.wiley.com/doi/10.1111/obr.12250.
- “Glycogen Is a Stored Form of Glucose. It Is a Large Multi-Branched Polymer of Glucose Which Is Accumulated in Response to Insulin and Broken down into Glucose in Response to Glucagon.” Diabetes, 6 Mar. 2020, https://www.diabetes.co.uk/body/glycogen.html.
- Rahmani, Jamal, et al. “The Influence of Fasting and Energy Restricting Diets on IGF-1 Levels in Humans: A Systematic Review and Meta-Analysis.” Ageing Research Reviews, Elsevier, 19 May 2019, https://www.sciencedirect.com/science/article/pii/S1568163719301035.
- Sonnenburg, Erica D., and Justin L. Sonnenburg. “Starving Our Microbial Self: The Deleterious Consequences of a Diet Deficient in Microbiota-Accessible Carbohydrates.” Cell Metabolism, Cell Press, 21 Aug. 2014, https://www.sciencedirect.com/science/article/pii/S1550413114003118.
- Whyte, Hilary EA, and SM Findlay. “Dieting in Adolescence.” OUP Academic, Oxford University Press, 1 Sept. 2004, https://academic.oup.com/pch/article-abstract/9/7/487/2648606.