Intermittent fasting as a way to lose weight, works, but there are important lifestyle considerations. This method involves applying a food consumption window at various times and duration throughout the day. You then abstain from eating during the other day/night hours.
This method requires your body to get used to the changes required by your metabolism. It also requires some mental adjustments related to fasting and not eating regularly, in ways you may be used to. You also have to cope with the inevitable hunger pangs. Finally, there are lifestyle choices for you, your family and those who may be affected by your prolonged fasts.
It is known that your body typically starts to burn fat after about 12 hours of fasting. So the most effective fasts are longer than 12 hours. Another obvious point is that to be effective you will need to restrict calorie intake during the 'eating periods'. Otherwise, the loss of calories during fasting will be quickly negated by overeating during the period of time between fasts.
On average, to effectively lose weight, you have to eat 500 calories less per day than you do normally. This creates a total calorie deficit of 3500 calories per week, which should translate into a loss rate of around 1 lb, or 500 g per week. You are allowed to drink water or green tea and other calorie free beverages and snacks during the fasting period.
Two common strategies that works for many people are the 16f/8e and 14f/10e fasting/eating periods (f=fasting;e=eat). For the first of these, you stop eating for about 16 hours straight, and only eat during an 8 hour window between these long fasts. This generally means adherents will have breakfast or their first meal for the day at 9 AM and their dinner at 5 PM Under normal circumstances your body will typically start to burn fat after about 12 hours of fasting. This schedule means that your weight loss via burning fat, starts at about 5 AM and continues for the next four hours. This somewhat extreme schedule, is very difficult for many people to maintain with a late breakfast and an early dinner.
The 14/10 schedule involves fasting for a 14 hour period and eating during the other 10 hours. This can mean you eat your first meal at 10 AM and your last meal at 8 PM. This schedule may be easier to follow and essentially means skipping breakfast. However, the time period after the 12 hours taken to switch to fat metabolism, is only 2 hours, about half that for the 16/8 schedule.
Intermittent fasting is most effective for weight-loss if practised daily. Some people find this very difficult to build into their work, social of family schedules. These people may opt to fast on alternate days, twice a week or over the weekend. Extreme fasting methods involving starving for 24-48 hours each week is not recommended. Fasting without drinking water, is also not recommended.
During fasting hours, many people experience:
This diet is not recommended for people who do manual labor, heavy lifting or builders. Similarly, children, pregnant women, the elderly, and those at risk of blood sugar fluctuations , such as people who take insulin oral medications for diabetes) should not diet using in intermittent fasting methods.
On the 5:2 day diet you typically eat your normal food on 5 days of the week. On the other 2 days you restrict your calorie intake to about 500 to 600 calories. This diet has also been referred to as the 'Fast Diet'. On the two fasting days, typically over the weekend, it’s recommended that men eat 600 and women just 500 calories on each day. As another example, you might eat normally every day of the week except for Mondays and Thursdays. On these 2 days, you eat 2 small meals of about 250 calories each for women, and 300 calories each for men.
See - The Two Day Fast Diet, 5:2 Diet, 5 day Feast and 2 days Fast Dieting
The Eat-Stop-Eat strategy involves adopting a 24-hour complete fast, once, twice or three times per week, between days on which you eat normally. For example, a complete fasting from dinner one day to dinner the next day adds up to a full 24-hour fast. You can also fast from lunch to lunch or from breakfast to breakfast. Drinks such as plain water, tea, coffee, herbal infusions and other zero-calorie drinks are permitted at all times during the fast. Such regular drinking is highly recommended. However, no solid foods can be eaten in the extreme version of the method. This method is generally not recommended for health reasons, and many people find it too difficult to continue over long periods of time. Some people eat a small snack if they get too hungry, especially when starting this method. Many religious groups practice regular fasts lasting an entire day.
In this version of East Stop Eat you fast every second day. There are many version of this approach with some allowing the consumption of about 500 calories during the fasting days. This is a difficult diet to maintain as you are very hungry several times a week. A typical calorie-restrictive diet may be better in the long run.
In this version of a Calorie Deficit, Low Carbohydrate, Unprocessed food diet the aim is to restrict calories by cutting out one meal a day. For most people 'Skipping Lunch' is the best option. You can start your day with a normal breakfast including whole food grains such as rolled oats in homemade muesli or wholegrain breads. You can enjoy dinner with your family with meat and green vegetables, but eliminating carbohydrate rich foods such as potatoes, rice and other starchy foods. One or two pieces of fresh fruit can be eaten during the day to cope with the hunger pangs. The 'Skip Lunch' version means that you have two 12 hours fasting periods between breakfast and lunch. Various tools are available to keep you in calorie deficit so you lose weight in a controlled way.
See - Calorie Deficit Calculator and WebApp
This diet involves only eating one large meal a day, generally at night. So, you fast all day, and eat a 'warrior feast' in the evening during a 4-hour eating window. Generally a few small snacks of vegetables and fruits are eaten during the day. The emphasis for the main meal is on 'paleo' style choices, mostly meat, low calorie vegetables and sticking to completely unprocessed, whole foods.
See - Paleo Diet Food List, Menu, Recipes - Caveman, Paleolithic Foods
In this option you simply skip meals from time to time, particularly when you don’t feel very hungry or can avoid it. Skipping meals occasionally is a spontaneous intermittent fast.
Many people have promoted the benefits of only 'eating when hungry' and staying 'a little hungry' all of the time. Many people eat regular meals as a habit rather than a need. This approach aims to reset your appetite to 'only eat when hungry' and to read what your body is telling you. It is also a constant reminder that you are trying to lose weight by eating less all of the time.
See - Intermittent Fasting Schedule, Weight Loss Plan and Tracking
See - How to Avoid Incessant Hunger Pangs When Intermittent Fasting