Intermittent fasting is a pattern of eating where you eat in a certain window, and refrain from eating in others. Depending on the intermittent fasting method you choose, these windows can range from several hours of fasting per day, to fasting every two days per week.
As a way to promote weight loss, intermittent fasting generally works by putting you in a calorie deficit, but many people do this for the other health benefits associated with it. When the body enters a “starvation” mode during fasting, due to low glucose levels, it then initiates a homeostatic process called autophagy, which may be useful in preventing disease.
But is intermittent fasting good for everyone? Are there negative side effects? Read on to discover the science behind intermittent fasting. And if you decide to go ahead, we recommend investing in one of the best water bottles to ensure you have enough fluids to stay hydrated. Plus, check out our tips on how to drink more water if you’re still struggling to get other fluids in.
What is intermittent fasting?
Intermittent fasting is where you refrain from eating for a period of time, or eating in a specific period of time, with the goal of changing your body composition and improving health outcomes. review in Nutrition Reviews He points out that fasting can be effective in reducing body weight in people of all sizes, with most studies focusing on cross-day fasting or all-day fasting experiences.
Dr. Norissa Kumaran, Medical Director and Founder Elemental Health ClinicExplains the concept of intermittent fasting further. “Intermittent fasting means changing the timing of your meals so that you eat foods and calories in a shorter eating period or changing eating patterns so that there are long periods when you don’t eat,” she says.
Types of intermittent fasting
Time Restricted Eating (TRE)
Time-restricted fasting is where there are 24-hour fasting and eating windows. This is usually organized into 16/8 or 14/10 windows, where you fast for 16 or 14 hours and eat during the smaller window. Since we tend to fast in our sleep, this tends to be the most practical option for most people and easily fits the nine-to-five lifestyle.
alternate day fasting
This pattern of intermittent fasting is perhaps the most intense, with one day fasting every other day of the week. On fasting days, you will reduce your calorie intake to about 25%, although some people choose not to eat at all. Then eat normally every day.
The 5:2 method of intermittent fasting works over an entire week, with two days of fasting and five days of regular eating. Fasting days may include small meals 200-300 calories, but some people choose to fast entirely for 24 hours.
Fasting 24 hours
This pattern of intermittent fasting usually takes place a maximum of several times a week and involves not eating for 24 hours, usually from breakfast to breakfast or lunch to lunch.
What happens during intermittent fasting?
One of the most notable results of intermittent fasting is that it can trigger the process of autophagy, in which the body cleans out dysfunctional cells and recycles parts of them into new cells. It’s a system that promotes the regeneration of healthy cells, removing mutated cells that can develop into cancer, as well as toxic proteins that may be responsible for the development of neurological conditions such as Parkinson’s and Alzheimer’s disease, according to one study in EMBO . magazine.
Autophagy begins after a period of fasting, and may be an evolutionary throwback from our hunter-gatherer days, where we would go for longer periods without eating due to the labor-intensive nature of obtaining food. search in Autophagy Journal He suggests putting your body into autophagy on a regular basis can help it function optimally by giving it the opportunity to “reset” and remove cellular debris. More research is needed, but a study in carcinogenesis It suggests that regular fasting that leads to autophagy as a response to “starvation” may be both cancer preventive and integral to tumor suppression, making it a promising area of cancer research.
In addition to autophagy, fasting causes the body to enter an alternate metabolic state, burning stored fat since carbohydrates are not available for energy. study in cell metabolism It indicates that fat metabolism produces ketones, which the body can use as an alternative source of energy. Similar to the way keto diet Leading to this alternate metabolic state, intermittent fasting can put you in a state called “ketosis” where you use ketones as fuel.
Is intermittent fasting safe for everyone?
If you are taking any medication, pregnant, trying to conceive, breastfeeding or have a chronic health condition, intermittent fasting is not recommended.
Dr. Kumaran advises special caution for people in the following groups:
- If you have a history of eating disorders
- If you have a low BMI or are underweight
- if you are prone to episodes of hypoglycaemia (low blood sugar)
- If you are taking prescription medications, especially medications to lower your blood sugar
- If you suffer from high levels of stress or suffer from insomnia
- If you are trying to conceive, pregnant or breastfeeding
- If you have had amenorrhea (absent or irregular periods)
- If you are a tween or teen, this is an important period of time for growth
If you fall into any of these categories, you can ask your doctor if supervised intermittent fasting is appropriate for your circumstances, but you probably need close monitoring.
This article is for informational purposes only and is not intended to provide medical advice.