How to do time-restricted fasting
It’s probably safe to say that what you eat is the most important factor in your diet. We all know that fruits and vegetables are good for us, and that we should stay away from things like trans fat and too much sugar. How much you eat also matters, and overeating even healthy food can lead to weight gain and other health problems. But more and more research is indicating that when you eat also has a major impact on your overall health and wellness.
“When you look at the world’s healthiest populations, none of them are eating the way most people do in the United States,” says Valter Longo, cell biologist and director of the Longevity Institute at USC. Even if you’re eating a healthy diet, eating too much or too often can cause health problems, says Longo, who has studied the effects of calorie restriction and fasting diets for 25 years.
Other health experts agree. Mark Mattson, a neurosciences professor at Johns Hopkins University and chief of the Laboratory of Neurosciences at the National Institute on Aging, advocates fasting diets for their ability to optimize cognitive performance. Three meals a day plus snacks is not the healthiest eating pattern, Mattson says in his 2014 TEDx talk on why fasting bolsters brain power (see video below). When we eat three meals a day, we never fully deplete our stores of glycogen (glucose stored in the body for fuel). Only after we deplete our glycogen stores do our bodies start to burn fat, which makes periodic fasting a great tool for weight loss. Even if weight loss isn’t a goal, the process of burning fat results in the formation of ketones — compounds that the brain can use for fuel. Research indicates that ketones may offer protective benefits for the brain, and promote an environment for better neural recovery and repair.
Fasting also increases production of proteins called neurotrophic factors, which promote strengthening of synapses and production of new neurons from stem cells, leading to improved cognitive performance. It also enhances the ability of nerve cells to repair DNA damage.
What is time-restricted fasting?
There are multiple ways to experience the benefits of fasting, one of which is known as time-restricted fasting. Also referred to as time-restricted eating or time-restricted feeding, this method of fasting involves limiting all eating to a set window during the day. Some advocates of time-restricted fasting eat all of their meals during a six- or eight-hour window, while others state that a 12-hour period is sufficient. That means that if you eat breakfast at 7am, you won’t eat any food after 7pm. This 12-hour break allows your body to burn off its glycogen stores and start burning fat.
How to do time-restricted fasting
Mattson compares fasting to exercise: if you’re not used to doing it and you jump right in, it may be difficult and you may not feel good. But the more you do it, the easier it will become and the better you’ll feel.
If you’re new to fasting, start with limiting your food intake to a 12-hour window. As it becomes easier, reduce your window to eight or eventually six hours. Theoretically, the longer you fast, the more fat stores your body will burn. You can drink water, coffee, or tea during your fasting period, with no sugar added.
Tips for success with time-restricted fasting
- Eat only when you’re hungry. You don’t have to have breakfast first thing in the morning — or at all. Mattson says that the idea that breakfast is the most important meal of the day is a myth. In fact, Mattson skips both breakfast and lunch most days, and eats only in the evening, and claims that he’s more productive as a result.
- You don’t have to do it every day — 3 or 4 days a week may be enough to experience benefits.
- For the best results, eat healthy foods, including quality protein, healthy fats, and lots of fruits and vegetables.
- Get plenty of healthy fats, which will help keep you feeling full longer. Don’t overlook beneficial plant-based fats such as coconut oil, avocados, walnuts, macadamia nuts, flax seeds, and chia seeds.
- Mix it up: Once you’re comfortable with time-restricted fasting, try other approaches to fasting and calorie restriction, such as intermittent fasting or a fasting mimicking diet, all of which can provide numerous health benefits.