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Intermittent Fasting...A Safe Route to Weight Loss, or Not
by Chris Moore, MS RDN CC
Fasting has been practiced by many cultures for centuries. The duration varies greatly as well as the reasons why food is abstained. A fast could be undertaken weekly or annually as a religious practice or sporadic, as a charitable, sacrificial, social and political change. I’m sure the names of Mahatma Gandhi or Dick Gregory come to mind; or the many prison hunger strikes in the name of unfair treatment.
By the time this paper goes to print, the final days of Lenten season (forty days prior to Easter) may be upon us, in which self-initiated fasts often occur. Individuals committing to the avoidance of a favorite dessert (or all), red meat, bread, bacon, alcohol or coffee (you name it) is reported as a sacrifice, but fasting is also overlooked is a way to pray and meditate. The religious reference to the topic at hand is just an introduction and that’s where I stop. I know to stay in my lane.
Intermittent fasting is being discussed as a possible approach to weight loss. With that in mind, it is generally practiced outside of a religious, social, or political scope; the intent is to maintain a usual eating pattern on some days, minimal or no food on other days through self- discipline.
Some may view this as ‘feast or famine’. More seriously, there are key populations when intermittent fasting is not recommended. These include pregnancy, diabetes (type 1 and 2), clinical diagnosed hypoglycemia (low blood sugar), bulimia nervosa, competitive athletes, and individuals with anorexia (no appetite) and unplanned weight loss secondary to cancer diagnosis and treatments. Also, food required before, after, or with certain medications should be followed as prescribed. Intermittent fasting can work for some.
• When the fast is short (one to two-day intervals), less-energy sources are consumed possibly (minimal deficit of daily needs); and balanced with mild activity, adequate fluids, uncontrollable hunger is not experienced as frequently and compliance can be fair to good; regular intakes then follow and the pattern repeats itself. The average and reasonable person can endure anything when the end is in sight. Or he or she knows within two days, I’m back to my usual. In addition to this, the human body has built in compensatory ways to cope with short term fasting.
• In isolated cases when approaching special occasions (50th birthday, class reunion, wedding, etc.) weight loss has been achieved, along with a boost of adrenaline and excitement. But the lasting effect is often short lived followed by the dreaded rebound. Most are smarter these days about such events.
• It can work for those who simply need a starting point or those who ask “give me just one thing to do” if the weight loss task appears overwhelming. Tools suggested in Experiments with Intermittent Fasting by Krista Varady, offer the approach of eating 25% less than one’s normal daily calories which may be 400-500 less (for women) and 500-600 less (for men), with an alternate-day fast; or comparative plans referred to simply as “5:2 rule in the FastDiet”. Basically, the two days on and five days off fasting concept. Those identifying as “snackers” generally are not successful with this.
• It works if ‘normal’ intake is defined, understood and compared to one’s calorie needs. Otherwise, this becomes too subjective to measure and difficult to comply. What is normal for one differs greatly from another. The frequency and duration of the fast can result in uncontrollable hunger. Weight loss may be achieved however at the risk of unstable blood sugar, reduced basal metabolic rate, muscle tone, bone density and anxiety, which present other long term detriments to ones well-being.
Sound & Key Approaches to Weight Loss
• Value self, not society’s norms
• Regular exercise
• Set small reasonable goals …stop gaining; positive impact on blood sugar, A1C, blood pressure, and blood lipids
• Adopt changes for a lifestyle, not weight loss
• Seek professional and knowledgeable help if needed
Let’s face it, if output exceeds intake long enough, the obvious will occur but at some risk. Further discussion on this subject and individual evaluation is a must. Fasting cannot be addressed without comparison of moderate versus rapid weight loss; or the impact on glycogen stores and ketosis. All are critical factors in safe weight loss and cannot be addressed entirely here. In conclusion, the miraculous human body can make appropriate adjustments when inadequate intake occurs for a period of time. And yes, weight loss can occur with intermittent fasting. But this is not the best approach. Fasting can be detrimental to key populations mentioned earlier. Deprivation over time can also lead to overeating, even binge eating, with potential muscle loss and slower metabolism. It is well documented that overall lifestyle changes has the most positive and lasting impact. To that point, it is not what one does on a given day or even two, but what happens over time that counts.
Look for a review of the meal plan ranked #1 for safe weight loss, overall health benefit, and maintenance in my next column.
The Fast Diet, M. Mosley and M. Spencer, 2013
Experiments with Intermittent Fasting, Varady, PhD. 2013
Nutrition Concepts & Controversies, Sizer and Whitney…body response to fasting. P. 342, 14th edition
Today’s Dietitian, Intermittent Fasting, B. W. Orenstein. Dec. 2014.