Ahh, picture this. You wake up on a cozy winter morning, still warm under the blankets. You inhale the wonderful aromatic mix of your thieves oil diffusing and of coffee brewing. As you put on your bunny slippers and walk downstairs, you even get a whiff of your favorite breakfast being prepped by your sweetie.
It’s 6:12 am and you haven’t eaten since 6:37pm the day prior. Smiling contentedly, you make your way to the kitchen, ready to enjoy your breakfast and coffee. Then, the itty bitty committee in your head begins. You know the buggers-the subtle echoes from the media personalities and various health experts all who cite conflicting evidence on what you should put in your belly and how you should move your bootie.
I have discussed the importance of individualizing dietary approaches in the past, and my recent digging into more research has further cemented this belief. For example, all of the following factors below affect your overall health and weight maintenance; it’s not just about what TYPE of or the TIMING of food. So, keep these factors in mind as you skim through my research assessing when you should break your fast from the day prior:
- Microbiome composition (your bug population in your body)
- Quality of foods chosen
- Stress & hormonal balance (they both affect each other)
- Digestive prowess (how well you absorb, eliminate, and assimilate your food choices)
- Exercise and activity level
- Genetics- variants in genes will determine how you burn calories, how effective different types of exercise are for you, your ability to detoxify environmental toxins, how you digest and assimilate your food, your response to stress, and if you are more sensitive to hormonal and glucose fluctuations than others.
The Intermittent Fasting Group
Back to your morning routine.
You are just about to grab your coffee and eggs and start to wonder if today will be a good day to try intermittent fasting (a dietary pattern that alternates fasting and non-fasting). After all, there’s been a lot of press on intermittent fasting and its many benefits. So, what should one do?
Intermittent Fasting Pros and Caveats
PROS
1. Periodic fasting has been touted with cardiovascular, longevity, and blood sugar benefits. (1-4)
Here is an infographic which demonstrates some of the benefits studied in various articles and journals:
2. Energy Restriction All Day All the Time May Not Be As Effective As Certain Restrictions Some Times
I found an abstract of one randomized study aimed at comparing restricting energy verses carbohydrate restriction in 115 overweight women with a family history of breast cancer. The women were randomized to a daily 25% decrease in energy intake (less food), an intermittent energy and carbohydrate restriction, or an intermittent carbohydrate and energy restriction with as much protein and fat as they desired. The women were followed for a 3-month weight-loss period and 1 month follow up maintenance period. The maintenance period was using either an intermittent energy restriction or intermittent energy restriction with as much protein and fat desired. It was found, that in the short term, intermittent calorie restriction of either type was superior to daily energy restriction for improving insulin resistance and body fat reduction. (5)
Importance: This study demonstrated the significance in a specific population and showed that, rather than restricting daily energy intake, intermittent fasting in overweight women may beneficial SHORT term. Furthermore, the conditions tested seem to point to the beneficial effect can also come from restricting carbohydrates in this population. (Note that some glucose is needed for thyroid conversion and hormonal health.)
Caveat: There wasn’t a comparison between decreased energy intake and intermittent fasting used in the maintenance phase. There was also a lack of health parameters in the abstract. In other words, insulin resistance improved, but what about other measures?
Major Cons
Sex Differences, Hormones, & Weight May Play a Factor
So, fasting may have its place as a therapeutic protocol for obesity, religious rituals, and could be used short duration to improve metabolic profiles. However, what about biochemical individuality?
Several studies indicate that women, specifically, non-obese women, may not benefit from intermittent fasting long term. (6-7)
In a 3 week alternate day fasting in non-obese subjects (8 men and 8 women with BMI 20-30 kg/m2) glucose and insulin response were measured at baseline and after 22 days of alternate day fasting (36 hour fast). Muscle biopsies were also performed. Interestingly, glucose response to a meal was slightly impaired in women and unchanged in men! However, insulin response was unchanged in women and reduced in men. There was a trend in modulating a gene involved in cellular stress and insulin management as a result of alternate day fasting.
DISCUSSION: Alternate day fasting may adversely affect glucose tolerance in nonobese women but not in nonobese men. The gene expression results indicate that fatty acid oxidation and mitochondrial biogenesis are unaffected by alternate day fasting. However, the increased expression in SIRT1 suggests that alternate day fasting may improve stress resistance, a commonly observed feature of calorie-restricted rodents. (6)
A great prospective for more on the hormonal effects and brain effects in women with intermittent fasting is reviewed here.
What About Breakfast? Read more here.
References:
- Study finds routine periodic fasting is good for your health, and your heart-Fasting found to reduce cardiac risk factors, such as triglycerides, weight, and blood sugar levels April 3, 2011. Eurekalert. http://www.eurekalert.org/pub_releases/2011-04/imc-sfr033111.php
- Intermittent fasting: a dietary intervention for prevention of diabetes and cardiovascular disease? British Journal of Diabetes & Vascular Disease. March/April 2013 vol. 13 no. 2 68-72. doi: 10.1177/1474651413486496
- Medical News Today. Intermittent Fasting Shown To Improve Diabetes And Reduce Cardiovascular Risk. April 2013. http://www.medicalnewstoday.com/releases/259769.php
- Trepanowski, J. F., Canale, R. E., Marshall, K. E., Kabir, M. M., & Bloomer, R. J. (2011). Impact of caloric and dietary restriction regimens on markers of health and longevity in humans and animals: a summary of available findings. Nutrition Journal. 10, 107. doi:10.1186/1475-2891-10-107
- The effect of intermittent energy and carbohydrate restriction v. daily energy restriction on weight loss and metabolic disease risk markers in overweight women. Br J Nutr. 2013 Oct 16;110(8):1534-47. Epub 2013 Apr 16.
- Glucose tolerance and skeletal muscle gene expression in response to alternate day fasting. Obes Res. 2005 Mar;13(3):574-81.
- Alternate-day fasting and chronic disease prevention: a review of human and animal trials. Am J Clin Nutr. July 2007 vol. 86 no. 1 7-13
- Shattering the Myth of Fasting for Women: A Review of Female-Specific Responses to Fasting in the Literature. Paleo for Women [website]. June 4, 2012.
Images Courtesy of iStock photo and mercola.com
