Intermittent fasting (IF) is currently one of the world’s most popular health and fitness trends. People are using it to lose weight, improve health and simplify their healthy lifestyle. Many studies show that it can have powerful effects on your body and brain, and may even help you live longer.
What Is Intermittent Fasting (IF)?
Intermittent fasting (IF) is a term for an eating pattern that cycles between periods of fasting and eating. It does not say anything about which foods you should eat, but rather when you should eat them. In this respect, it is not a “diet” in the conventional sense. It is more accurately described as an “eating pattern.” Common intermittent fasting methods involve daily 16 hour fasts, or fasting for 24 hours, twice per week.
Humans have actually been fasting throughout evolution. Sometimes it was done because food was not available, and it has also been a part of major religions, including Islam, Christianity and Buddhism. When you think about it, our hunter-gatherer ancestors didn’t have supermarkets, refrigerators or food available year-round. Sometimes we couldn’t find anything to eat, and our bodies evolved to be able to function without food for extended periods of time. If anything, fasting from time to time is more “natural” than constantly eating 3-4 (or more) meals per day.
Intermittent fasting (IF) is a term for an eating pattern that cycles between periods of fasting and eating. It is currently very popular in the health and fitness community.
How to Do Intermittent Fasting
Intermittent fasting has been very popular for many years and several different methods have been used. All of them involve splitting the day or week into “eating periods” and “fasting periods.” During the fasting periods, you eat either very little or nothing at all.
These are the most popular methods:
- The 16/8 Method: Also called the Leangains protocol, it involves skipping breakfast and restricting your daily eating period to 8 hours, for example from 1 pm to 9 pm. Then you “fast” for 16 hours in between.
- Eat-Stop-Eat: This involves fasting for 24 hours, once or twice a week, for example by not eating from dinner one day until dinner the next day.
- The 5:2 Diet: On two non-consecutive days of the week, only eat 500-600 calories. Eat normally the other 5 days.
By making you eat fewer calories, all of these methods should make you lose weight as long as you don’t compensate by eating much more during the eating periods.
There are several different ways to do intermittent fasting. All of them split the day or week into “eating periods” and “fasting periods.”
How Intermittent Fasting Affects Your Cells and Hormones
When you fast, several things happen in your body on the cellular and molecular level. For example, your body changes hormone levels to make stored body fat more accessible. Your cells also initiate important repair processes, and change the expression of genes.
Here are some changes that occur in your body when you fast:
- Human Growth Hormone (HGH): The levels of growth hormone skyrocket, increasing as much as 5-fold. This has benefits for fat loss and muscle gain, to name a few.
- Insulin: Insulin sensitivity improves and levels of insulin drop dramatically. Lower insulin levels make stored body fat more accessible.
- Cellular repair: When fasted, your cells initiate cellular repair processes. This includes autophagy, where cells digest and remove old and dysfunctional proteins that build up inside cells.
- Gene expression: There are changes in the function of genes related to longevity and protection against disease.
These changes in hormone levels, cell function and gene expression are responsible for the health benefits of intermittent fasting.
When you fast, human growth hormone levels go up and insulin levels go down. Your body’s cells also change the expression of genes and initiate important cellular repair processes.
Health Benefits of Intermittent Fasting
Many studies have been done on intermittent fasting, in both animals and humans. These studies have shown that it can have powerful benefits for weight control and the health of your body and brain. It may even help you live longer.
Here are the main health benefits of intermittent fasting:
- Weight loss: As mentioned above, intermittent fasting can help you lose weight and belly fat, without having to consciously restrict calories.
- Insulin resistance: Intermittent fasting can reduce insulin resistance, lowering blood sugar by 3-6% and fasting insulin levels by 20-31%. This should protect against type 2 diabetes.
- Inflammation: Some studies show reductions in markers of inflammation, a key driver of many chronic diseases.
- Heart health: Intermittent fasting may reduce LDL cholesterol, blood triglycerides, inflammatory markers, blood sugar and insulin resistance. These are all risk factors for heart disease.
- Cancer: Animal studies suggest that intermittent fasting may help prevent cancer.
- Brain health: Intermittent fasting increases a brain hormone called BDNF, and may aid the growth of new nerve cells. It may also protect against Alzheimer’s disease.
- Anti-aging: Intermittent fasting can extend lifespan in rats. Studies showed that fasted rats live as much as 36-83% longer.
Keep in mind that the research is still in its early stages. Many of the studies were small, short in duration or conducted in animals. Many questions have yet to be answered in higher quality human studies.
Intermittent fasting can have many benefits for your body and brain. It can cause weight loss, and may protect against type 2 diabetes, heart disease and cancer. It may also help you live longer.
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