What is Intermittent Fasting (IF) and why should you do it?
Intermittent fasting is a healthy and highly effective method of restricting calories and losing unwanted body weight and reducing obesity related illness in overweight adult women.
According to the most recent data, 70% of US adults are overweight or obese.1 Obesity remains one of the largest threats to the health of our nation putting millions of Americans at increased risk for chronic diseases. Among this threat, obesity rates are 5% higher women; with females being twice as likely to be extremely obese compared males.2 Given the current obesity epidemic there is a growing need for effective dietary approaches.
Aside from weight loss IF has also been linked to many other health benefits such as:
- disease prevention
- reduced insulin levels
- reduced inflammation
- improved risk factors for coronary heart disease
- low blood pressure
- extended life span5
Calorie restriction has been one of very few interventions that has consistently proven to support weight loss.
Intermittent Fasting is making a conscious decision to restrict calories in whole or in part during certain periods of time
There are several ways to implement IT.
The best schedule would be a self-selected meal timing window that fits into your lifestyle. A few examples include:
- Daily: Restricting calories 16 hours and consuming all of your calories in an 8 hour window
- Alternate Day: Severely restricting calories every other day
- 24-hour: Restrict calories two times per week for 24 hours
- Spontaneous: whenever skipping a meal is most convenient.
How does it work?
IF switches your body’s source of energy. Your body’s primary sources of energy are glycogen stores and blood glucose. It takes approximately 8 hours for your body to metabolize glucose after a meal has been consumed3; thus the human body enters into a fasted state around 8 hours after eating, once it has finished absorbing its nutrients. Once all of your glucose and sugars are used up for energy your body then switches to burning fat for fuel.
Ta-da! You are now in a fasted state!
Burning fat = weight loss!
IF is not a diet, but rather a dieting pattern that is as unique as you are!
What can you eat?
Research suggests that a diet high in fat is equally effective as a low fat fasting diet in helping obese subjects lose weight and improve obesity related risk factors.9 Unlike other diets, IF does not require you to change your dietary intake, only your diet schedule. This gives you the opportunity to focus only on the pattern of your food consumption instead of the macronutrients in the foods you consume in order to experience the benefits of weight loss.
A long term IF plan will always prove healthiest when in conjunction with a whole food based diet consisting of: healthy fats, high quality proteins, complex carbohydrates and unrestricted quantities of vegetables and moderate exercise.
No One Size Fits All
IF is one strategy for adult obese women to consider in their search for weight loss.
If you’re overwhelmed with the latest in trendy yo-yo diets; IF warrants a good introductory option to aid in the battle against obesity. Lasting weight loss and weight maintenance does require extensive dietary counseling to instill healthy behaviors that can be employed on a more long term basis. Regular appointments with your healthcare provider and Registered Dieticians play an important role in combatting long term obesity and learning overall wholesome food based diets.
Avoid IF if you are:
- Pregnant, trying to get pregnant, or breastfeeding
1.Obesity and Overweight. Centers for Disease Control and Prevention website.
Published June 13, 2016. Accessed
January 26, 2017.
2. Overweight and Obesity Statistics. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/health-statistics/Pages/overweight-obesity-statistics.aspx. Published October 2012. Accessed January 26, 2017.
3. Azizi Fereidoun. Islamic Fasting and Health. Annals of Nutritional & Metabolism. DOI:
4. Collier, Roger. Intermittent fasting: the next big weight loss fad. CMAJ.JAMC medical knowledge matters. 2013 doi: 10.1053/cmaj.109-4437
5. Tiver, Allegra. Alternate-day fasting improved weight loss in adults with obesity; best as dinner or small meals. Obesity Week. 2014
6. Klempel MC., Kroeger CM, Bhutani S, Trepansowski JF, Varady KA. Intermittent fasting combined with calorie restriction is effectice for weight loss and cardio-protection in obese women. Nutrition Journal. 2012,11:98
7. Johnstone, A. Fasting for weight loss: an effective strategy or latest diet trend? International
Journal of Obesity. 2015 39, 727-733
8. Varady Krista A., et al. Alternate day fasting for weight loss in normal weight and overweight subjects: a randomized controlled trial. Nutrition Journal. 2013, 12:146
9. Klempel MC, Kroeger CM, Varady KA. Alternate day fasting (ADF) with a high-fat diet produces similar weight loss and cario-protection as ADF with a low-fat diet. Metabolism
10. Varady, Krista A. Impact of intermittent fasting on glucose homeostasis. Current opinion in clinical nutrition and metabolic care. DOI: 10.1097/MCO.0000000000000291
11. Griggs RL, Potter C, Brunstrom JM. Intermittent fasting: not as hungry as you expected? Appetite. doi.org.une.idm.oclc.org/10.1016/j.appet.2016.02.080
12. Kliewer, K.L.; Ke, J.Y.; Lee, H.Y.; Stout, M.B.; Cole, R.M.; Samuel, V.T.; Shulman, G.I.; Belury, M.A. Short-term food restriction followed by controlled refeeding promotes gorging behavior, enhances fat deposition,and diminishes insulin sensitivity in mice. J. Nutr. Biochem. 2015, 26, 721–728.
13. Harvie M, Howell A. Potential Benefits and Harms of Intermittent Energy Restriction and Intermittent Fasting Amongst Obese, Overweight and Normal Weight Subjects-A Narrative Review of Human and Animal Evidence. Behavioral sciences. 2017
14. Medical Complications of Obesity photo taken from https://commons.wikimedia.org/wiki/File:Medical_complications_of_obesity.png. This file was derived from: Adult Obesity-CDC Vital Signs-August 2010.pdf. 21 August 2012 Accessed February 19, 2017.