Intermittent fasting is a dietary regimen that alternates between periods of eating and periods of fasting. Unlike traditional diets that dictate what foods to eat, intermittent fasting specifies when to eat those foods. In this regard, it’s not a diet in the conventional sense but more of an eating pattern. Common intermittent fasting methods include daily 16-hour fasting or fasting for 24 hours 2-3 times a week.
Variations of Intermittent Fasting
There are several different approaches to intermittent fasting, each involving dividing your day or week into eating and fasting periods. During fasting, you either consume very little or no food at all. Notably, fasting periods should exclude proteins and carbohydrates. One of the most popular methods is the 16/8 protocol, also known as the Leangains protocol. It involves skipping breakfast and limiting your daily eating window to 8 hours, like from 1:00 PM to 9:00 PM, followed by a 16-hour fasting period between meals.
How It Affects Your Cells and Hormones
When you fast, several cellular and molecular processes occur in your body. Here are some of them: fasting increases human growth hormone levels and lowers insulin levels. At a cellular level, fasting alters gene expression and triggers vital cellular repair processes.
A Potent Tool for Weight Loss
Weight loss is a common reason why people turn to intermittent fasting. By naturally reducing your calorie intake, intermittent fasting can lead to automatic calorie reduction. Additionally, it changes hormone levels, promoting weight loss. It increases the production of the fat-burning hormone norepinephrine.
Due to these hormonal changes, intermittent fasting can boost metabolism by 3.6-14%. It helps you eat less and burn more calories, resulting in weight loss. Research shows that intermittent fasting can be a potent weight loss tool. A 2014 review demonstrated weight loss of 3-8% over 3-24 weeks, which is significant compared to many other weight loss studies. Another study indicated that intermittent fasting leads to less muscle loss than standard calorie restriction diets. It’s an effective way to lose weight and shed abdominal fat.
However, remember that its primary success lies in reducing overall calorie consumption. If you overeat or consume a lot during eating periods, you may not lose weight at all.
Health Benefits
Here are the key health benefits of intermittent fasting:
- Weight Loss: As mentioned earlier, intermittent fasting can help you lose weight and shed abdominal fat without calorie counting.
- Insulin Resistance: Intermittent fasting can reduce insulin resistance, lower fasting blood sugar by 3-6%, and reduce fasting insulin levels by 20-31%, which may protect against type 2 diabetes.
- Inflammation: Some studies show a reduction in markers of inflammation, a key factor in many chronic diseases.
- Heart Health: Intermittent fasting can lower LDL cholesterol, triglycerides, inflammatory markers, blood sugar levels, and insulin resistance—risk factors for heart diseases.
- Cancer: Animal studies suggest that intermittent fasting may prevent cancer.
- Brain Health: Intermittent fasting increases brain-derived neurotrophic factor (BDNF) and may promote the growth of new nerve cells. It may also protect against Alzheimer’s disease.
- Anti-Aging: Intermittent fasting can extend the lifespan of rats. Studies show that fasting rats lived 36-83% longer.
Keep in mind that research is still in its early stages. Many studies were small, short-term, or conducted on animals. Many questions remain to be answered in larger human studies.
Makes a Healthy Lifestyle Easier
Eating healthily is simple, but sustaining it can be incredibly challenging. One of the main obstacles is the work required for planning and preparing healthy meals. Intermittent fasting simplifies this because you don’t need to plan, cook, or clean up after as many meals as before. For this reason, it’s popular among lifehack enthusiasts as it improves health while simplifying your life.
Who Should Be Cautious or Avoid It?
Intermittent fasting is not suitable for everyone. If you are underweight, have a history of anorexia, or have had bulimia in the past, you should avoid fasting without consulting a healthcare professional. In such cases, intermittent fasting can be harmful.
Should Women Fast?
There is some evidence that intermittent fasting may be less beneficial for women than for men. There are reports of women whose menstrual cycles stopped when they started intermittent fasting and returned to normal when they resumed their previous eating patterns. For this reason, women should exercise caution when considering intermittent fasting.
If you have trouble getting pregnant, you may want to abstain from intermittent fasting for now. This eating pattern is likely not suitable if you are pregnant or breastfeeding.
Is there anything else you’d like to know or clarify about intermittent fasting?
Best Types of Intermittent Fasting for Women
When it comes to diets, there is no one-size-fits-all approach, and this applies to intermittent fasting as well. In general, women should approach fasting with more caution than men. Here’s the best type of intermittent fasting for women:
Crescendo Method: Fasting for 12-16 hours two to three days a week. The fasting days should be non-consecutive and evenly distributed throughout the week (e.g., Monday, Wednesday, and Friday).
During fasting periods, it’s still important to eat well. If you consume a large amount of unhealthy high-calorie food during eating periods, you may not achieve the same weight loss and health benefits. Ultimately, the best approach is one that you can sustain over the long term and doesn’t lead to any adverse health effects.
Safety and Side Effects
Hunger is the main side effect of intermittent fasting. You may also feel weak, and your cognitive function may not be as sharp as you’re used to. This can be temporary as your body may need some time to adapt to the new eating schedule. If you have any underlying medical conditions, it’s essential to consult a doctor before trying intermittent fasting. This is especially important if you:
- Have diabetes.
- Have blood sugar regulation issues.
- Have low blood pressure.
- Take medications.
- Are underweight.
- Have a history of eating disorders.
- Are trying to get pregnant.
- Have amenorrhea (lack of menstrual periods).
- You are pregnant or breastfeeding.
In general, intermittent fasting is very safe. There is no risk in not eating for a while, provided you are overall healthy and eat a balanced diet. However, if you experience any issues, such as a disrupted menstrual cycle, discontinue fasting immediately.
Frequently Asked Questions
Here are answers to some common questions about intermittent fasting:
Can I drink fluids during fasting?
Yes. Water, coffee, tea, and other non-caloric beverages are fine. Avoid adding sugar to your coffee. A small amount of MCT oil is acceptable. Coffee can be particularly helpful during fasting as it can curb hunger.
Isn’t skipping breakfast bad?
No. If you eat healthily for the rest of the day, skipping breakfast is not harmful.
Can I take supplements during fasting?
Yes. However, keep in mind that some supplements, like fat-soluble vitamins, are better absorbed with food.
Can I exercise during fasting?
Yes, working out on an empty stomach is okay.
Will fasting cause muscle loss?
All weight loss methods can lead to some muscle loss, so it’s important to lift weights and maintain a high protein intake. One study showed that intermittent fasting results in less muscle loss compared to regular calorie restriction.
Will fasting slow down my metabolism?
No. Research shows that short-term fasting can actually increase metabolism. However, longer fasting periods of three or more days may suppress metabolism.
Should children fast?
Allowing a child to fast is likely a bad idea.
Let’s Get Started
Chances are, you’ve already intermittently fasted many times in your life. If you’ve ever had dinner, gone to bed, and not eaten until lunch the next day, you’ve likely fasted for more than 16 hours straight. Some people naturally eat this way—they just don’t feel hungry in the mornings. Many people find the “16/8” method to be the simplest and most reliable form of intermittent fasting. It won’t be surprising if you want to start with this practice.