The Pros and Cons of Intermittent Fasting

The Pros and Cons of Intermittent Fasting

Posted by Lori Shemek; December 8, 2017

Intermittent fasting is a practice within the span of history. The regular three meals a day habit is really perceived as an anomaly from the perception of evolution.

However, before the standard three meals a day intake became a norm, not more than 4-5 thousand years ago, the rest of human history was nothing more than switching between fasting for days (they didn’t have easy access to food like we do today) with an occasional binge (once you kill a Mammoth, you have to eat it fast, before it went bad!).

Intermittent fasting is basically about fasting and eating periods that can vary in length. Interestingly, there are many protocols you can choose to accommodate your comfort level.

Some find it very convenient practicing 16 hours of fasting and 8 hours of eating window while others eat regularly for five days and then fast for two days (not more than 500Kcal intake per day). Also, there are more extreme protocols as well; one day fast followed by one-day regular eating.

No matter, if you are already practicing intermittent fasting or just thinking about it, here are some pros and cons that will help you better understand the whole concept:


Here are some important health benefits documented from some studies on the effects of intermittent fasting on human health.

Flipping the Metabolic Switch

Intermittent fasting has been shown to decrease insulin resistance—lowering diabetes risk and enhancing metabolism. Intermittent fasting has also been shown to have a positive effect on the hunger hormone ghrelin.

This process breaks down the fat, resulting in weight loss and it works through this simple mechanism.  During the fasting period, insulin level drops. So once the insulin level goes down- fat breakdown begins. As soon as the reservoirs of carbohydrates are depleted, the body flips the metabolic switch- instead of glucose, it turns toward free fatty acids as a primary source of energy. Ketosis kicks in and the body and brain actually prefer using ketones that are created as a source of energy over glucose.

Utilization of free fatty acids for energy means fat breakdown (or weight loss). How long does it take to spend all the glucose before switching to fat? Depending on the energy expenditure and the number of carbs in deposit (liver and muscles), it could take anywhere from a few to thirty-six hours.

Increase in our Mitochondria  – Our Cellular ‘Batteries’

We have what equates to a ‘battery’ in each of our cells and they are our mitochondria. When they are not happy, we are not happy. We are tired, inflamed and overweight. Intermittent fasting helps to increase the amount and health of these important organelles. Mitochondrial health is a key component to optimal health.

Intermittent fasting also promotes autophagy, the natural ‘cellular housekeeping’ process where the body clears debris and other things that stand in the way of the health of mitochondria, which begins when liver glycogen is depleted. Autophagy happens more powerfully at 14 hours of fasting on up. The longer you fast, the more autophagy occurs.


Decrease in Visceral Fat Mass AKA Belly Fat

When doctors talk about the detrimental effects of obesity on health, they are talking about the impact of visceral fat. It may surprise you that the majority of obesity-related health risks are caused by visceral fat deposit (the fatty tissue that builds up inside the abdominal and thoracic cavity- around the heart, liver, kidneys, etc.). Based on the research done so far, intermittent fasting breaks down the visceral fat quite efficiently.

Improvement of the Lipid Profile

The improvement of the “bad” to “good” cholesterol ratio and the decrease of total cholesterol and triglycerides level lowers the risk of heart disease and stroke and slows down the process of atherosclerosis.


Weight Loss

A few things happen when we fast, insulin increases when we eat, but when we fast, Insulin, our fat storage hormone, decreases dramatically. Lower levels of insulin facilitate fat burning. Also, levels of growth hormone may increase and this hormone helps to increase fat loss, muscle growth and other added benefits.

Intermittent fasting also increases cellular health that has a healthy impact as well upon the functioning of our mitochondria. The healthier our mitochondria, the more energy, less inflammation and leaner we are.

Reducing Inflammation and Oxidative Stress

As the fat tissue volume reduces and the leptin hormone secretion drops, tissue inflammation decreases. Intermittent fasting slows down ‘inflammaging’ and helps prevent some metabolic diseases such as diabetes.

The Increase of Growth Hormone Level

Human growth Hormone increases with intermittent fasting. HGH is what helps the body regenerate while asleep. Benefits of HGH include: increased energy levels, exercise performance, lean muscle mass,


Though intermittent fasting has a lot of pros, not everybody can handle intermittent fasting diet.

Hunger- Hangry- Binge Cycle

Some people just can’t handle missing meals because it affects their work performance, cognition and energy levels. They feel exhausted and sick during the fasting period because of hunger. When you have conditioned your body to rely upon food at a certain time, withdrawing does have its 1-2 week period of adjusting. But once adjusted, the desire for food generally disappears.

However, there are those that feel negative effects while intermittent fasting and disordered eating can occur such as obsessive thinking about food, binging/purging or eating an excess amount of food.  

While the majority of people do have success with intermittent fasting, others just can’t. And that’s perfectly fine – if you find yourself in this group, do not despair, there are some other dietary regiments you can follow to improve your health and weight. Remember we are all unique and what works for one does not mean it will work for you.

Not Drinking Enough Water

Water is a crucial key to intermittent fasting success. When we are fasting, digestion rests and our cells can do a cellular housekeeping – sweeping out all cellular debris and toxins resulting in optimized health and mitochondrial health. Inflammation and poor mitochondrial health go hand-in-hand.

There is a specific type of water that I use – alkaline hydrogen water that boasts a plethora of benefits including weight loss and reducing inflammation. The reason this water has such a huge following is that it contains hydrogen, the smallest molecule that can easily penetrate the cell wall and the mitochondria as well, promoting impressive health benefits.

Not a Good Choice for Everybody

Intermittent fasting is not the best choice for adolescents, pregnant and lactating women. Also, the elderly or people with metabolic diseases (diabetes or thyroid gland dysfunction, for example) should consult their doctor or nutritionist before trying intermittent fasting. Women, for example, have a very sensitive hormone balance and just a tweak to it can promote unwanted effects.

There is a Learning Curve Not Everybody is Willing to Overcome.

It is imperative to understand that intermittent fasting is not one of those diet plans you try three weeks before summer to tone up the body. It is a lifestyle choice – a schedule of eating. But, before it becomes your second nature, you are likely to make some regular mistakes like undereating. Yes, not eating enough!

Again, there is a thin line between body recomposition and body decomposition. The amount of calorie intake has to be sufficient to lose the fat tissue and KEEP your muscles. With a lowered energy intake, muscle wasting can occur and this is an important negative effect if not careful.  Undereating means losing fat AND muscle. We want to keep our muscle. Overeating means weight gain.

The best way to balance the food intake to keep the muscles and lose fat is to incorporate enough protein and a nutrient dense diet at every meal.

Bottom Line

If you are not one of those people who gets grumpy if the lunch is 15 minutes late and can tolerate hunger well or have never had the habit of breakfast, you stand a good chance of enjoying all the health benefits of the intermittent fasting diet. The key is to go slow if you decide to give it a try no matter which camp you belong in.

In case you don’t suit any of the descriptions above, try some of the simpler intermittent fasting protocols. Start reducing your carb intake at each meal, the graduate with a 12 hours fast and gradually increase to 16 hours fasting period. If you find it to be comfortable, keep practicing intermittent fasting- in the long run, it will do wonders for your health!




  • Varady KA. Intermittent versus daily calorie restriction: which diet regimen is more effective for weight loss? Obes Rev2011;12:e593-e601.
  • Anton, S. D., Moehl, K., Donahoo, W. T., Marosi, K., Lee, S. A., Mainous, A. G., Leeuwenburgh, C. and Mattson, M. P. (2017), Flipping the Metabolic Switch: Understanding and Applying the Health Benefits of Fasting. Obesity. doi:10.1002/oby.22065
  • Patterson, R. E., Laughlin, G. A., Sears, D. D., LaCroix, A. Z., Marinac, C., Gallo, L. C., … Villaseñor, A. (2015). INTERMITTENT FASTING AND HUMAN METABOLIC HEALTH. Journal of the Academy of Nutrition and Dietetics, 115(8), 1203–1212.



©2019 DLS HealthWorks, LLC.  Lori Shemek, PhD, CNC health and weight loss expert.  Bestselling author of How To Fight FATflammation! and the bestselling author of  ‘Fire-Up Your Fat Burn!’