You must have heard or read somewhere that intermittent fasting is the secret to CAPS for weight loss. Similarly, according to her followers, this popular nutritional program has many benefits for our overall health. But what is the reality? Can you lose weight, improve your health, or even increase your life expectancy through fasting? What does science say?
Intermittent fasting according to science
“While there is solid scientific evidence for the benefits of intermittent fasting, it is neither a quick fix nor a guaranteed one-size-fits-all solution.” That’s the opinion of Satchin Panda, a researcher and professor of circadian biology at the Salk Institute in California. He has dedicated his career to studying the complex biochemical processes in the human body, and his studies in mice and humans show that intermittent food deprivation can benefit human health in many ways, including weight loss.
Before we dive into the dark science, it should be mentioned that there is more than one way to practice the nutrition program in question. For example, there is the 5:2 diet, which consists of fasting or eating very few calories (about 500-600) on two non-consecutive days of the week and eating normally on the rest of the days. However, perhaps the most popular method is the so-called 16/8 intermittent fasting, which advises you to eat all your meals within an 8-hour window and refrain from eating for the next 16 hours.
All intermittent fasting methods are essentially based on the same idea: when you reduce your calorie intake, your body uses stored fat for energy. But what makes our diet different from the days, weeks, and months of calorie restriction advocated by traditional diets is that restricting calories consumed over a limited period of time is easier for most people. In addition, a certain type of intermittent fasting that Panda has studied may have additional beneficial effects.
What does a typical program look like?
Panda focused on a method of intermittent fasting known as time-limited eating. Its format is similar to what is known as 16/8, but the researcher expands the window from 8 to 12 hours. Let’s say you usually start your day with breakfast and your first cup of coffee at 7 am. Let’s also assume that you relax with a glass of wine and a plate of cheese around 11:00 pm. For limited meal times, you will need to check in for breakfast at 8am including coffee and finish dinner at 6pm. So you eat all of your meals within a 10-hour window and cut out calories from desserts, evening snacks, and alcohol. But that is not all.
Experiment on laboratory mice
According to science, time-restricted eating appears to provide more benefits to the body than simply reducing calorie intake. Proof ? Results from a 2012 study (link below) that Panda and colleagues conducted with genetically identical mice. They fed them the same food, a version of the standard American lab mouse diet, high in fat and simple sugar and low in protein.
Although both groups received the same type and quantity of food, one group had access to food for 24 hours and the other only 8 hours. Since mice are nocturnal, they usually sleep during the day and eat at night. But the group that had access to food 24 hours a day began to eat it during the day, while continuing to sleep as usual.
After 18 weeks, mice that could eat at any time showed signs of insulin resistance as well as liver damage. But the mice that ate during the 8-hour window were not affected by such conditions. They also weighed 28% less than mice with 24-hour access to food, even though both groups of mice consumed the same number of calories per day!
Revolutionary test results
This was a historic moment for scientists, as until that time, researchers were of the opinion that the total number of calories, and not the time they were consumed, determined weight loss or gain. The team repeated the experiment with three additional groups of mice and got the same results. The scientists extended the eating window to 3 p.m. and found that the shorter it was, the less weight the mice gained. Of course, the human body is more complex than the mouse, but these experiments were the first evidence of the importance of timing when it comes to how our bodies use food.
Intermittent fasting and the circadian rhythm
In recent years, scientists have discovered that many processes in the human body are related to our circadian rhythm. For example, early morning sunlight is good for our mood and sleep, and exposure to blue light from screens after 8 pm through our mobile phones, computers, etc. can disrupt our nighttime sleep. Similarly, eating at the right time can nourish us and even heal us, while healthy food at the wrong time can be unhealthy food. Instead of being used as fuel, it is stored as fat, which only makes sense when you know the basics of how human metabolism works.
Sources used: idea.ted.com