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A Handle on your Health: Intermittent Fasting

Tuesday, November 19, 2019

I am no fan of diets. Most diets can work, for a while, but most people tend to “yoyo” up and down with dieting. They apply themselves for a while but soon they fall back into old habits. It can be difficult to alter the types of food you eat for long term and so many diets are hard to sustain. How are you going to make the change to a high protein low carbohydrate “keto” diet when you love spaghetti and fettuccine? Well maybe intermittent fasting may be your answer because it doesn’t tell you what to eat but rather when to eat.

Intermittent fasting (IF) actually has lots of good research to support it, unlike some other diets. If you think about it, we humans lived a fasting lifestyle in our early history. We were hunter-gatherers so food wasn’t readily available to us like it is now. While popular press has made intermittent fasting more well known over the last 5 years, the research into it goes back decades. Sure, most of this research involves rats and mice but the results are very good.  

The study results in humans for weight-loss with intermittent fasting are good but really no better than any other diet. Whether you’re doing the Atkins diet or Weight Watchers or South Beach or intermittent fasting (IF) everyone loses weight. The cool thing with IF is that it has benefits to your health that go beyond just weight loss. To understand some of these benefits we need an understanding of what IF does at the cellular level to our bodies.

For IF to work we need our bodies to enter a state of catabolism where it is breaking down stored energy sources (fat) and using them up to run our metabolism. So you have to fast long enough to induce the body’s machinery to convert over to catabolism. 

There are several ways this can be done. The most popular seems to be the 16:8 model, where you eat only during an 8-hour period in the day. Some people prefer to fast for 24 hours two days out of the week. Either option will cause the body to lower its insulin level, which is key for IF to work.  

When you eat food, especially carbohydrates, your body releases insulin which is a hormone that tells your cells to bring sugar (glucose) into the cells for energy but when you don’t eat for awhile your insulin level goes down and your cells instead get a signal to stop bringing sugar in and instead cut up stored fats for energy.  

One concern for people trying to lose weight is muscle loss. Anytime you begin a diet to lose weight you are at risk of also losing some muscle. With intermittent fasting, however, Human Growth Hormone (HGH) levels actually go up. Elevated HGH levels send signals to cells to burn fat but also to build muscle. So for you gym rats out there, IF may be a better way to eat for you instead of eight small meals a day, which is time consuming to plan and make. If you do work out on an IF diet, you may want to supplement yourself with some branched chain amino acids before your workouts.

Norepinephrine also gets released with IF which acts to stimulate your metabolism and produce more weight loss. IF also acts to release the brain hormone BDNF which acts to encourage the growth of new neurons and synapses which may help in brain function. Studies are being done to see if this can help reduce the occurrence of Alzheimer’s disease. Heart health may be improved too, as LDL (bad cholesterol) levels are lower with IF as is blood pressure. Insulin resistance, which is the main problem in type II diabetics, is improved significantly with IF. Rats also showed to live longer (36-83% longer) on an IF diet plan. For us humans that could mean instead of dying at 80, you would make it to the ripe old age of 146. Honestly not sure if I want to live that long.

Who should be careful with this style of eating? Advanced diabetics, children, people suffering with bulimia or anorexia and pregnant women should probably avoid IF.  In fact, women as a group do not benefit as much from IF as men do. If you’re trying to get pregnant IF can disrupt normal menstrual cycles.

When is the best time of the day to fast? A better question is when can I eat? An Alabama study found that eating between the hours of 7a.m. and 3 p.m. (circadian rhythm eating) produced the best results. Nighttime eating, as a general rule, produces more obesity.  

IF has also been found to be sustainable. Once you get through the transition and become used to feeling hungry part of the day, this diet can be continued throughout your lifetime. You still get to eat the things you enjoy eating and as long as you don’t gorge yourself at mealtimes you will maintain or lose weight. You should still be picking healthy food, though, and staying away from processed carbohydrates and sugars. 


Dr. John Turner is a family medicine and emergency medicine doctor with 25 years of experience. He is also the owner of My Primary Care Clinic and My Emergency Room 24/7 here in Hays County. Dr. Turner may be reached at 512-667-6087.

San Marcos Record

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