Intermittent Fasting (IF) is a broad term to describes dietary strategies that involve recurring periods of fasting and eating. When practicing IF, individuals go for long periods of time with little to no caloric intake. After the fast is over, all of the day’s calories are eaten in the remaining allotted time. The time someone spends fasting varies a great deal and can range anywhere from 12 hours to several days. There are many reasons someone may choose to fast; centuries ago, ancient philosophers would use fasting as a way to stimulate thinking and it has long been used as a part of different religious practices. Recently, IF has become popular, seen as a quick and easy way to lose weight, and research is not only backing that up, but proving that it also brings many more health benefits.
How it works
- Here’s a quick break down of our how body uses the food we eat for energy
- The food we eat is broken down into simple sugars
- These sugars enter our blood stream and our blood sugar rises
- Our pancreas is triggered to release insulin
- Insulin “unlocks” our cells so the sugar can be used for energy
- Any sugar not used is either stored in the liver as glycogen or converted to fat
Whez we fast, our insulin levels stay low and our cells are not able to use sugar for energy. When our body can’t use sugar for energy, it triggers our liver to release glycogen for energy; after that is used up, our body begins to break down our fat cells for energy. This is the general theory behind how and why intermittent fasting can help with weight and fat loss.
It turns out that those ancient philosophers had the right idea when they chose to skip a few meals to boost their brainpower. All animals, including humans, rely on their ability to hunt in order to survive, and if we are able to stay focused and with a clear mind, we are better able to catch our prey and survive. Research on rats has shown that even in caloric restriction approaching starvation, the brain size of the rats remained the same while the size of other organs (like the heart, liver, gut, and muscles) decreased by as much as 40-50%. Limited research in animals has also shown a positive link between IF and prevention of certain diseases, like cancer and many cardiovascular and neurological conditions. Studies on rats have shown that different forms of IF can result in lower blood pressure and heart rate, and lower accumulation of lipids in the liver. These same studies show that IF may also help retain muscle mass in a caloric restriction and improve cognitive function. IF also gives your digestive system time to rest, which can help promote healthy bowel function, regulate digestion, and improve metabolism.
Which way is best?
There are endless ways to schedule your fast and the optimum way just depends on what works best for you. Below are four common methods used for intermittent fasting.
1. Leangains: In this method, men fast for 16 hours and women fast for 14 hours, followed by eating in the remaining 8-10 hours of the day. It is important to keep the eating window at a consistent time, otherwise hormone imbalances can occur. Women should also keep their fasting window to a maximum of 14 hours, due to risk of hormone imbalances. Most people find it easiest to fast throughout the night and into the morning, with an eating window in the afternoon/evening. Another focus of the Leangains method is adjusting your intake and timing your macronutrient intake around your workout schedule.
2. Eat Stop Eat: This is also known as the 5:2 method and involves fasting for two days of the week, while eating normally on the other days. You can still consume calorie-free beverages during the fasting period and can break your fast whenever and however you want.
3. The Warrior Diet: According to this method, you should fast all day and eat one large meal, or at least the majority of your calories in the evening. The theory behind this method is that consuming all of your calories at this time allows your body to utilize those nutrients to repair your muscles and recuperate, and allows your body to produce hormones and burn fat during the day. You are allowed to have a few snacks consisting of vegetables, fruit, and lean protein throughout the daily “fast”, but the majority of calories should be consumed within the four-hour period before bed.
4. Alternate Day Fasting: This method alternates eating minimal calories one day, followed by eating “normally” the next. On the “fasting” days, calories should be restricted to approximately 20% of your usual intake. While this method may seem easy to follow, it can be easy to overeat on your “normal” eating days, which can lead to unhealthy eating habits.
Regardless of which method of intermittent fasting you choose, it isn’t the magic answer to all of your weight-loss goals. There are many benefits to IF, but losing weight still requires some form of caloric deficit and choosing whole, unprocessed foods will help you stay fit and healthy. While IF can be a useful diet strategy for many, it isn’t for everyone. Remember to always check with your health care provider before starting any new diet or weight loss regimen. People with pre-existing health conditions should only start a new health program under the supervision of a professional.