Your city
Categories
 +31 (0)6 5107 9358
0Cart
Yvana van den Hork  •  17-02-2018

Health benefits and dangers of intermittent fasting

Health benefits and dangers of intermittent fasting

Health benefits and dangers of intermittent fasting

Last week we explained how the celebration of carnival and the ensueing Lent with a partial fast can have mental health benefits for you.
Fasting is part of almost every single religion mostly because it originally was very hard to avoid, as every civilization has to endure periods with famine due to lack of food at the end of winter when food stores are at its lowest. Or in hotter climates, when there is a severe drought.
So it made sense to make peace with unavoidable famine espeically when it is short-lived.

But what if I told you that fasting could actually be healthy for you? That is, fasting for a short period of time. This practice has been adopted by an ever growing amount of people, who mostly adopt a method called intermittent fasting.
Intermittent fasting is said to lead to easier fat loss, increased stamina and vigor, improved focus at the gym and at work, breaking plateaus and, improved immune health.

Intermittent fasting effectively mimics the eating habits of our ancestors, who did not have access to grocery stores or food around the clock. They would cycle through periods of feast and famine, and modern research shows this cycling produces a number of biochemical benefits. In short, by altering what and when you eat, you can rather dramatically alter how your body operates.

Fasting is historically commonplace as it has been a part of spiritual practice for millennia. But modern science has confirmed there are many good reasons for fasting, including the following:

1 Normalizing your insulin and leptin sensitivity, and boosting mitochondrial energy efficiency: One of the primary mechanisms that makes intermittent fasting so beneficial for health is related to its impact on your insulin sensitivity. While sugar is a source of energy for your body, it also promotes insulin resistance when consumed in the amounts found in our modern processed junk food diets. Insulin resistance, in turn, is a primary driver of chronic disease—from heart disease to cancer.

2 Intermittent fasting helps reset your body to use fat as its primary fuel, and mounting evidence confirms that when your body becomes adapted to burning FAT instead of sugar as its primary fuel, you dramatically reduce your risk of chronic disease

3 Normalizing ghrelin levels, also known as "the hunger hormone"

4 Promoting human growth hormone (HGH) production. Research has shown fasting can raise HGH, which plays an important part in health, fitness, and slowing the aging process. HGH is also a fat-burning hormone, which helps explain why fasting is so effective for weight loss

5 Lowering triglyceride levels and improving other biomarkers of disease

6 Reducing oxidative stress: Fasting decreases the accumulation of oxidative radicals in the cell, and thereby prevents oxidative damage to cellular proteins, lipids, and nucleic acids associated with aging and disease.

There's also plenty of research showing that fasting has a beneficial impact on longevity in animals. There are a number of mechanisms contributing to this effect. Normalizing insulin sensitivity is a major one, but fasting also inhibits the mTOR pathway, which plays an important part in driving the aging process.

Intermittent fasting has also been identified as a potent ally for the prevention and perhaps even treatment of dementia. First, ketones are released as a byproduct of burning fat, and ketones (not glucose) are actually the preferred fuel for your brain.

In addition to that, intermittent fasting boosts production of a protein called brain-derived neurotrophic factor (BDNF), which activates brain stem cells to convert into new neurons, and triggers numerous other chemicals that promote neural health. It also protects your brain cells from changes associated with Alzheimer's and Parkinson's disease. Research suggests that alternate-day fasting (restricting your meal on fasting days to about 600 calories), can boost BDNF by anywhere from 50 to 400 percent, depending on the brain region.

How to apply intermittent fasting?

Intermittent fasting is an umbrella term that covers a wide array of fasting schedules. As a general rule, it involves cutting calories in whole or in part, either a couple of days a week, every other day, or even daily.
The 5:2 fasting plan calls for normal eting for five days a week, and fast for two. This schedule is sometimes referred to as the "5:2" intermittent fasting plan. On fasting days, it is recommended to cut down food intake to 25% of your normal daily calories, or about 600 calories for men and about 500 for women, along with plenty of water and tea.
A variation on this fasting plan is called eat-stop-eat in which you eat ZERO calories for 24 hours from dinner to dinner.
The problem with this method is that a full 24-hour fast can be fairly difficult for many people. It is easier to start at 14-16 hours and work up from here.

Another common variation is the alternate-day fast in which the fast can be as long as 32-36 hours. The drawback is that it requires you to go to bed with an empty stomach every other day, which can be tough for most people—at least initially. The advantage is said to be that on the other day you are allowed to eat ach much as you want, which supposedly leads to a higher compliance rate than many other fasting schedules.
In this version you consume the same amount of calories on fasting days as in the 5:2 plan, but because there are more fasting days, you are allowed to eat more calories on non-fasting days. While you eat less more often, it doesn't feel as restrictive because you get a 'reward' the other day. In most studies, fasting worked best when people only ate one large meal of 500kcal a day for lunch or dinner.
Splitting the 500 calorie meal up into multiple smaller meals throughout the day was not as successful as eating just one meal, once a day.
If you're truly eating just 500 calories in a day, you will lose weight. But when eating tiny amounts of food multiple times a day, you're far more inclined to want more, so the cheat rate dramatically increases.

VThe method known as 'Fast till 5' is possibly the simplest method of all and only requires you to do what millions of busy people do when they leave for work: skip to simply restrict your daily eating to a specific window of time, such as an eight hour window.
There is a more extreme version in which the eating window is further compressed to just 4 hours. This method goes by the name Warrior Diet and is combined with paleo-diet.
Finally, there's a 'skip when convenient' method that allows you to skip whatever meal you fancy, when you don't feel hungry or are too busy to cook.

TCombining my own experience that I would get both cranky and hyper-alert from fasting in the morning and was unable to sleep when I didn't have dinner as well, I arrived at a method in which I would simply skip lunch but eat breakfast at 10am and a very late dinner at 10pm , resulting in a 12 hour fast every other day. 

Another  reason to not skip breakfast was fear for muscle breakdown. At a time when it was still recommended to eat every few hours when you wanted to put on muscle, skipping meals for as many as 16 hours seemed ludicrous. So I felt better to just skip lunch, a meal I'd often be too busy for anyway.

For women specifically this method may work best as they generally can only tolerate shorter fasts of a bit over 12 hours. Their cortisol levels remain higher for longer, which can lead to excess muscle loss and raised stress levels. It can even lead to worse insulin resistance rather than improved glucose tolerance. For some it can also lead to a slower metabolism. 

I have followed this method of alternate 12:12 hr fasts for well over 5 years, which worked so well because I was also following a strict every-other-day workout schedule. Most of the time I'd work out in the morning and eat a post-workout meal right afterwards. 

What are the health risks of intermittent fasting?

At its most extreme with fasts lasting as much as 24 hours, there is a danger of overeating.
Some will start feeling guilty or ashamed, which may trigger or worsen existing bulimia and other eating disorders.

You can create an unhealthy obsession with food due to an inability to eat when others are enjoying their lunch or snack foods at work. With IF, that could become an obsession with mentally planning your next meal. Among people who survived a period of extreme famine, a majority seems to have changed careers in which they took up a profession in which they worked with food, e.g as cooks in a restaurant. 

You can create an unhealthy obsession with food due to an inability to eat when others are enjoying their lunch or snack foods at work. With IF, that could become an obsession with mentally planning your next meal. Everything becomes about food.

You might over-rely on coffee or caffein. Especially for slow metabolizers, that third cup of coffee or 3rd tablet of caffein could cut into your sleep cycle. Make sure to not have any coffee or caffein 6-8 hours before your planned bed time.

You could increase food intolerances and inflammation when you break the fast with junkfood loaded with inflammatory ingredients such as gluten and sugar. Never mind the blood sugar crash after an overload of sugars.

People that should avoid fasting are those experiencing chronic stress and have a cortisol dysregulation. It goes without saying that pregant and nursing women shouldn't fast as they need to feed a growing infant.
Fasting is also not recommended to people that are prone to have an abnormal low blood sugar level (hypoglycemia). It's commonly associated with diabetes, but you can be hypoglycemic even if you're not diabetic.

I hope this article has helped you to decide for yourself if intermittent fasting is worthwhile for you.


Author

Yvana van den Hork
Rank: Senior Editor
Position: Director
She holds an MSc in Toxicology and Biology of the Wageningen University
All author posts