Intermittent fasting is an ace up the sleeve of those who are struggling to lose weight and regulate blood sugar. You don’t have to do much reading to see articles online touting the benefits. Does that mean it’s great for everyone? Absolutely, not. Read on for a discussion of the pros and cons of intermittent fasting to find out if it could help you reach your health goals.
What is Intermittent Fasting?
Intermittent fasting has been described many ways. In the research, it is really all about when you are eating your food. Rather than fasting for days at length, intermittent fasting refers to eating very little to no food for 8-24 hours a time. There are many variations. Intermittent fasting could mean you skip a meal a few times a week, not eating for one day a week or eating all your food for the day at the evening meal. Some studies have also looked at eating as much as you want one day and very little the next day and alternating after that but this was a challenging method to stick with. (1)
Intermittent fasting helps people lose weight and protect their heart.
Intermittent fasting has been shown to assist with metabolism regulation. It’s particularly helpful in those with uncomplicated cardiovascular disease, Type II diabetes, high blood pressure and obesity. Here is how it helps:
- Weight loss is achieved by reducing body fat while preserving muscle mass
- LDL cholesterol and triglycerides decrease (bad cholesterols)
- HDL levels are preserved (good cholesterol)
- Blood sugar decreases
- Blood pressure decreases (1,2)
How fasting works
While intermittent fasting can be very helpful to regulate metabolism, it’s important to understand how it works. When we fast, the body knows that food is unavailable. This means that for the first 18 hours or so the body burns stored carbohydrates. After that, the body has to switch to burning fats and a day or two later that is accompanied by breaking down muscle to produce glucose. (5)
Fasting makes you stressed
The fasting state increases our body’s stress hormone, cortisol. Cortisol increases energy so we can deal with a stressor, in this case fasting. In healthy people, the changes that occur when fasting aren’t harmful. But, if you’re overworked, sick or ill, not sleeping well or dealing with stressful family and life events it may not be a good time to fast. (6) The rise in cortisol during fasting can also increase anxiety in susceptible individuals and aggravate insomnia. (7)
Slippery slope – when fasting makes you feel too good
It’s important to note that fasting may help manage symptoms but does not often resolve health issues on it’s own. Many people with fatigue, food sensitivities and gastrointestinal issues feel better when they don’t eat. Unfortunately, that positive benefit can lead to development of a disordered relationship with food. (8,9)
For these reasons, I don’t recommend intermittent fasting to people with a history of extreme dieting or disordered eating. I do advocate for treating the underlying cause of these health issues. If you’re avoiding food to feel better or have more energy this a sign of deeper health issues that need to be addressed.
Fasting isn’t the same for males and females
Fasting and weight loss can also alter hormone balances. Females are particularly susceptible to this effect. Intermittent fasting may be much less beneficial for females than males. If you’re female and looking to implement intermittent fasting it is very important to be working with a knowledgeable practitioner. (10)
Who should not intermittent fast?
Type I diabetics should not intermittent fast. Children should not intermittent fast. Those who have physically demanding jobs or are underweight should not fast. It should also be avoided during pre-pregnancy, pregnancy and breastfeeding. You should always consult a physician or naturopathic doctor before embarking on an intermittent fasting plan.
Intermittent fasting can be very effective for restoring healthy metabolism in the right people. It is a powerful tool that should be treated with respect and implemented under supervision of a knowledgeable professional.
- Tinsley GM, La Bounty PM. Effects of intermittent fasting on body composition and clinical health markers in humans. Nutr Rev. 2015 Oct;73(10):661-74 http://www.ncbi.nlm.nih.gov/pubmed/26374764 Accessed May 2, 2016
- Varady KA, Bhutani S, Church EC, Klempel MC. Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and carioprotection in obese adults. Am J Clin Nutr November 2009 vol.90 no.5 1138-1143 http://ajcn.nutrition.org/content/90/5/1138 Accessed May 2, 2016
- Johnson JB, Summer W, Cutler RG, Martin B, Hyun DH, Dixit VD, Pearson M, Nassar M, Tellijohann R, Muadsley S, Carlson O, John S, Laub DR, Mattson MP. Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma. Free Radic Biol Med. 2007 Mar 1;42(5):665-74 http://www.ncbi.nlm.nih.gov/pubmed/17291990 Accessed May 2, 2016
- Dukowicz AC, Lacy BE, Levine GM. Small intestine bacterial overgrowth: a comprehensive review. Gastroenterol Hepatol (NY). 2007 Feb;3(2): 112-122. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3099351/ Accessed May 2, 2016
- Klien S, Sakurai Y, Romijn JA, Carroll RM. Progressive alterations in lipid and glucose metabolism during short-term fasting in young adult men. Am J Physiol. 1993 Nov;265(5 PT 1):E801-6.http://www.ncbi.nlm.nih.gov/pubmed/8238506 Accessed May 2, 2016
- Tomiyama AJ, Mann T, Vinas D, Hunger JM, DeJager J, Taylor SE. Low calorie dieting increases cortisol. Psychosom Med. 2010 May;72(4):357-364. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2895000/ Accessed May 2, 2016
- D’aurea C, Poyares D, Piovezan RD, Passos G, Tufik S, Mello MT. Objective short sleep duration is associated with the activity of the hypothalamic-pituitary-adrenal axis in insomnia. Arg Nueropsiquiat. 2015 Jun;73(6):516-9.http://www.ncbi.nlm.nih.gov/pubmed/26083888 Accessed May 2, 2016
- Quick VM, Byrd-Bredbenner C, Neumark-Sztainer D. Chronic illness and disordered eating: a discussion of the literature. Adv Nutr. 2013 May; 4(3)::277-286. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3650496/Accessed May 2, 2016
- Moreno-Domínguez S, Rodríguez-Ruiz S, Fernández-Santaella MC, Ortega-Roldán B, Cepeda-Benito A. Impact of fasting on food craving, mood and consumption in bulimia nervosa and healthy women participants. Eur Eat Disord Rev. 2012 Nov;20(6)461-7 http://www.ncbi.nlm.nih.gov/pubmed/22764071
- Ruper S. Shattering the myth of fasting for women: a review of female-specific responses to fasting in the literature. Paleo for Women Blog. June 4, 2014. http://paleoforwomen.com/shattering-the-myth-of-fasting-for-women-a-review-of-female-specific-responses-to-fasting-in-the-literature/ Accessed May 2, 2016