Intermittent fasting (IF) is a diet plan that cycles between a period of fasting and non-fasting over a defined time.
It is one of the most popular health and fitness trends worldwide that people follow to lose weight, control blood pressure and cholesterol, improve health, and simplify their lives.
Unlike other diet plans, intermittent fasting doesn’t tell you what to eat. Instead, it tells you when to eat.
Several studies show that this diet plan has beneficial effects on your brain, as well as your body. Experts even claim that it can help you live longer. [1, 2]
Continue reading to get a detailed idea about intermittent fasting, how it works, and the pros & cons you may experience by following this diet plan.
Methods of Intermittent Fasting
There are several ways to follow intermittent fasting — all of them involve dividing the time into fasting and eating periods.
In the common method, you basically fast for 16 hours or 24 hours, two days a week.
The other methods involve eating very little or no meal at all.
Some of the most popular methods are:
The 16/8 method: In this method, you need to skip your breakfast and limit your food consuming period to 8 hours, such as 1 PM-9 PM. You will also keep fasting for 16 hours in between.
Eat-Stop-Eat: This method requires fasting for 24 hours, once or twice a week. You can do it by skipping a meal from lunch or dinner one day until lunch or dinner the next day respectively.
The 5:2 Diet: This technique involves eating normally five days a week, but limiting calorie consumption to only 500-600 calories on two non-consecutive days.
Of all these methods, the 16/8 method is the most famous due to its simplicity and sustainability.
No matter which method you follow, it should help you lose weight by reducing calorie intake. Just make sure that you do not eat much during the eating periods.
Intermittent Fasting: What Effect Does It Have on Your Body?
Various things happen in your body when you fast, including:
Insulin: Fasting improves insulin sensitivity and reduces insulin level, which makes stored body fat more accessible. [3]
Human Growth Hormone (HGH): While on intermitted fasting, the human growth hormone (HGH) level increases, which helps in fat loss and muscle gain. [4, 5, 6, 7]
Gene Expression: Several positive changes happen to your genes, including protection against some diseases, and ensuring longevity. [8, 9]
Repairing Cells: While fasting, the old and dysfunctional proteins inside your cells get digested or removed. This process is known as autophagy. [10, 11]
These changes in your cells and genes are responsible for the health benefits you enjoy by following intermittent fasting.
Health Benefits of Intermittent Fasting
Various studies have shown the positive effects of intermittent fasting. However, most of the research are in their early stages and conducted mostly on animals.
Some confusions are not yet solved in high-quality human studies. [12]
1. Intermittent Fasting Aids in Weight Loss.
Intermittent fasting is known to be a powerful weight-loss tool, which makes it one of the popular diet plans for people to try. [13]
Your calorie intake reduces as you take fewer meals. Besides, your body releases norepinephrine, a fat-burning hormone when you’re fasting.
Short-term fasting like IF can increase your metabolic rate upto 14% by bringing changes in hormones. [14, 15]
As intermittent fasting involves eating fewer and burning more calories, you can enjoy a faster weight loss.
In fact, a 2014 research states that you may experience 3-8% faster weight loss by following IF, compared to other weight loss diet. [1]
However, to make this weight loss process faster, you have to make sure that you don’t eat too many foods during your eating periods.
2. It May Treat Type-2 Diabetes.
Intermittent fasting can be beneficial for those who are suffering from diabetes.
Consuming high-calorie food is a reason your blood sugar levels get high, increasing the risk of diabetes. As this diet involves eating fewer calories, the chances of blood sugar spikes become low.
Research has proved that following this diet plan can reduce blood sugar by 3-6% and fasting insulin levels by 20-31%, thus protecting you from type-2 diabetes. [1]
3. Intermittent Fasting Can Reduce Inflammation.
While inflammation is considered good for your body, chronic inflammation can be a key driver to several diseases.
A 2007 study published in the journal Free Radical Biology & Medicine shows that calorie restriction on the alternate day can reduce markers of inflammation and oxidative stress. [16]
Some other studies have also confirmed the ability of intermittent fasting to reduce inflammation. [17, 18]
4. It May Boost Heart Health.
Inflammation, high blood sugar, cholesterol, insulin resistance — all of these can increase the risk of cardiovascular diseases.
Following intermittent fasting can reduce blood sugar levels, insulin resistance, and even inflammation. [1]
A study published in 2013 shows this diet plan can improve your metabolism, which is important for a healthy heart. [19]
The efficacy of short-term fasting in reducing heart disease has already been proved in a study published in 2009. [20]
Other Health Benefits
Apart from helping you lose weight and reducing heart disease risk, intermittent fasting can be beneficial in some other ways as well.
Several studies show that following IF may help to grow new nerve cells and increase the brain hormone BDNF. It may also protect you from Alzheimer’s disease. [21, 22, 23, 24]
Some animal studies conclude that intermittent fasting could increase the lifespan of lab rats by 36-83%. [25, 26]
Besides, some studies suggest that this diet plan may prevent cancer. However, evidence has been limited to animal research. [27, 28, 29]
Side Effects and Precautions
While intermittent fasting can provide numerous health benefits, it has some side effects as well.
The most common side effects you may experience are hunger and weakness. However, these problems are temporary as your body takes some time to adapt to this new meal system.
You are suggested to consult a doctor before following intermittent fasting if you have the following health condition:
- Diabetes
- Under certain medications
- Low blood pressure
- Underweight
- Eating disorder
- You’re pregnant or a breastfeeding mom
Who Should Avoid This Diet?
Intermittent fasting is definitely not for everyone. In fact, some studies suggest this diet is not as useful for women as it is for men.
While following IF can improve insulin sensitivity in men, it can worsen this condition in women. [30]
According to some animal studies, following intermittent fasting made female rats infertile, emaciated, and caused them to miss cycles. [31, 32]
Women may also miss their period when they are in this diet. Besides, intermittent fasting is not a good idea for those who have issues with fertility, and those who are trying to conceive.
Bottom Line
Intermittent fasting is more of a lifestyle change than a diet plan. Although it can improve your health in many ways, it’s not something you need to follow.
If you can take care of yourself by eating healthy, doing exercise, and taking enough sleep, fasting is not a necessary option for you.
However, if you are fit enough to follow intermittent fasting, you can follow it to lose weight, improve your heart health, and even increase your lifespan.
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