You can’t open a fitness magazine or scroll through a health blog without reading about intermittent fasting. Intermittent fasting (IF) is a way of eating, used for weight loss and health benefits. One of the critical differences between IF and a traditional diet is that fasting is often a way of life. It is not simply a lose-weight-quick strategy, but a way of eating to maintain a healthy weight, improve metabolic health and even live longer.
The diet culture as we know it doesn’t work. Plenty of research has found that these strict ways of eating, where you cut out certain foods, count calories and consistently restrict yourself, only lead to weight gain in the end. Diet culture peaked in the early 2000s. This was evident in the popular TV show called Biggest Loser, where contestants would compete to see who could lose the most weight. This often entailed grueling workouts to the point of throwing up and extreme calorie restriction. In 2016 a study called the Biggest Loser study was published in the journal Obesity.
In this study, 14 Biggest Loser competitors participated. Their weight loss and weight were measured at the end of the competition as well as their resting metabolic rate (RMR). After 6-years, the researchers again calculated their weight and RMR. The researchers found that the participants had experienced significant metabolic slowing and had gained most of the weight back. This is often what happens with diets like these and is why so many people find they continue to gain weight year after year, diet after diet.
Intermittent fasting is believed to prevent the slowing of your metabolic rate. It stops the dreaded weight loss plateau and keeps your metabolic rate in check. Dr. Kumar, a specialist at the Comprehensive Weight Control Center at Weill Cornell Medicine and New York-Presbyterian, told Everyday Health, “Most people who try diet and exercise to lose weight tend to fall off the wagon and regain the weight. Hormones that promote weight regain, like hunger hormones, are kicked into full gear, and the thought is that intermittent fasting may be a way to prevent this metabolic adaption from happening.”
When you go for an extended period without eating, your body undergoes several changes. For example, your insulin levels drop which facilitate fat burning and human growth hormone levels increase significantly which promotes fat burning and muscle gain. Additionally, genes and molecules change, protecting against disease while the body also induces cellular repair processes.
Weight loss is also a huge benefit, but you must ensure you don’t eat more calories after your fast. For example, just because you missed breakfast doesn’t mean you can eat whatever you want for dinner. When you maintain a regular diet, in addition to fasting, you will end up consuming fewer calories. In 2011, a review found that intermittent fasting resulted in less muscle loss than a continuous calorie restriction and a 2014 review found that IF caused a 3 – 8% weight loss in 3 – 24 weeks.
Another benefit of IF is that it can reduce inflammation and oxidative stress. Oxidative stress involves free radicals, which cause damage to DNA and protein. Research has found that when you fast, you can improve your body’s resistance to oxidative stress. These benefits extend to your heart as well. For example, it has been shown to reduce risk factors of heart disease by lowering blood sugar levels, blood triglycerides, total and LDL cholesterol, and blood pressure.
Lastly, some research suggests that intermittent fasting can help prevent cancer. Several animal studies have found that its effect on metabolism may help cancer development. Though research is still needed on humans, these preliminary findings are promising. When pursuing IF, you may need to try different ways. Many different types of fasting cater to different lifestyles, preferences, and needs.
6 Different Types of Intermittent Fasting
1. Fasting Overnight
This way of fasting is considered the easiest as you will be fast asleep on your millet pillow for most of your fast. Typically you will start fasting after dinner around 7 p.m. and eat again the next day at 7 a.m. If you are not used to fasting, this is an excellent way to start. It shares many similarities and benefits with circadian fasting, which we discussed on our blog, The Hype Over Circadian Fasting and Why It Works.
2. The 5:2 Fasting Method
This method was shared in detail in the popular fasting book entitled The Fast Diet. With this type, you won’t go without food altogether but will instead restrict calories two days a week. So, you will eat a regular, balanced diet where you don’t count calories for five days. Then, you will cut your calories to 500 - 600 a day on the remaining two days. Just because you can still eat on those two days doesn’t mean it’s any easier. You will still be very hungry and counting down the hours until you eat again.
3. The 16:8 Fasting Method
This method is quite simple – no eating for 16 hours and an 8-hour window to eat. During your 16 hours (which can be scheduled for whenever works for you), you will only be allowed to consume water and beverages with no calories. Following your fast, you can continue to eat but only have an 8-hour window to do so. This method is very popular with those who want to try fasting for its weight loss benefits and blood sugar control. Even though you can continue eating during the 8-hour window, you will still end up in a slight calorie deficit. On the other hand, you will benefit from the weight-loss-enhancing hormone changes, as mentioned earlier. This can be done multiple days a week for fast results, or you can do it once a week.
4. Full Day Fasts
This method involves one or two 24-hour fasts a week. While on a fast day, you can only have calorie-free beverages like water, herbal tea, or black coffee. This method of IF can work for someone who doesn’t like counting hours, calories, or scheduling the time they can eat. It makes it simpler and more flexible. For example, you can choose the day of the week that works best for you so you can still go to your friend's birthday dinner or work lunch. Like all other fasts, you need to be mindful of the food you consume on non-fast days. You don’t need to count calories, but you need to stay on track and eat a moderate amount of calories and healthy foods. This benefit is that you don’t feel like you are on a diet 5 – 6 days a week.
5. The Every Other Day Fast
With this type of fast, your fast days will be low-calorie, with roughly 25% of your daily calorie needs. So, for example, on Monday you will eat normally; Tuesday you will only have 500 calories; Wednesday eat a normal diet; Thursday eat 500 calories, and on so. Dr. Krista Varaday published a study on this approach in Nutrition Journal, stating that it was effective in helping adults lose weight.
6. Fast When You Can
This is the most flexible fasting option of the fasts listed here. Essentially you will fast each day, tracking how long each fast is. You can do this with the help of various apps. Each day, you start your fast clock after you finish your last meal (e.g., dinner) and then stop the clock when you eat again. For an extended fast, some may eat dinner and then not eat again until lunchtime. Some days you’ll fast for 16 hours, others 12. Each day will differ, but each day you will go without food for an extended period.
Each of these ways of fasting can be effective, but what works best for you will depend on your schedule and what you find easiest. Consistency is key. Intermittent fasting can become a lifestyle, not a fad diet that is followed for four weeks. Consider when you are hungriest. If you are hungrier earlier in the day, you may want to start your fast earlier so you can enjoy breakfast in the morning. When fasting, don’t forget to stay hydrated. This will help you feel better during your fast and keep your body functioning as it should.
Although intermittent fasting can be very beneficial, it isn’t for everyone. Medical experts recommend pregnant women, those on certain medications or who have a history of eating disorders not engage in IF. For most people, the most significant side-effect is hunger. In addition, with dipping blood sugar levels, you can start to feel “hangry” and may struggle to get through the day. If you can, plan your fasts for days when you don’t have much to do. For example, if you are completing a 24 hour fast, do it on a day where you can relax at home, lay on your millet pillow, or spend time on your meditation pillow.