Intermittent fasting (IF) is a way of eating that switches between fasting (not eating) and eating on a regular schedule. Research shows that intermittent fasting could be an effective way to manage your weight and prevent — or even reverse — some forms of ill health. But how do you do it? And is it safe? Turn over to find out more.
The main types of IF
· The 16:8 method (lean-gains protocol), involves restricting your daily eating period to 8 hours, such as 11am-7pm. Then you fast for 16 hours in between. It is still a good idea to have a healthy breakfast when you eat, especially if your lunch and dinners are not super healthy.
· The 5:2 diet - where you consume only 500–600 calories on two non-consecutive days of the week but eat normally the other 5 days.
By reducing your calorie intake, these methods should cause weight loss if you don’t compensate by eating much more during the eating periods. Many people find the 16:8 method to be the simplest, most sustainable and easiest to stick to. Longer periods without food, such as 24, 36, 48 and 72-hour fasting periods, are not necessarily better for you and may be dangerous. Going too long without eating might encourage your body to start storing more fat in response to starvation.
How does IF work?
To understand how intermittent fasting leads to fat loss we first need to understand the difference between the fed state and the fasted state.
Fed (absorptive) state (0-4 Hours): For the first four hours after eating our body is in the fed state when it is digesting and absorbing food. After an average meal consisting of carbohydrates, proteins, and fats, a lot of glucose is available during this phase. When you are in the fed state, it's very hard for your body to burn fat because your insulin levels are high. It is a high energy dependant process.
Post–absorptive state (4-12+ Hours): This is when your body isn’t processing a meal – once food has been digested, absorbed and stored. The body needs to burn through its glycogen stores in the liver, muscle and adipose tissue first before it can use fat for energy. The capacity of these stores depends on stature and body size. Therefore, they cover almost precisely the individual daily requirement of each person. Sometimes this stage can last longer.
Fasted state (12+- Hours): This is when your insulin levels will be low enough so your body can now start to burn fat. It does this by creating ketones (ketosis) that certain [not all] parts of your body can use as energy. Firstly, it will favour a process called gluconeogenesis where it uses protein sources to create ‘new’ glucose. The longer you fast into the 16hrs+ period then your body will go into ketosis. Fasting puts your body in a fat burning state that you rarely make it to during a normal eating schedule.
IF benefits
Increases human growth hormone (HGH) levels: Blood levels of HGH may increase dramatically, which facilitate fat burning and muscle gain, and has numerous other health benefits.
Gene expression: There are beneficial changes in several genes and molecules related to longevity and protection against disease.
Can help you lose weight and visceral fat: Fasting lowers insulin levels but increases HGH levels and amounts of noradrenaline that all increase the breakdown of body fat and facilitate its use for energy.
Can reduce insulin resistance, lowering your risk for type 2 diabetes: Anything that reduces insulin resistance should help lower blood sugar levels and protect against type 2 diabetes.
Induces various cellular repair processes: Fasting causes the cells in the body initiate a cellular “waste removal” process called autophagy that involves the cells breaking down and metabolizing broken and dysfunctional proteins that build up inside cells over time.
· This may provide protection against several diseases, including cancer and neurodegenerative diseases such as Alzheimer’s disease.
Has benefits for your brain: What’s good for the body is often good for the brain as well.
· IF improves various metabolic features known to be important for brain health, such as reducing oxidative stress and inflammation.
What can I eat while intermittent fasting?
During the times when you’re not eating, water and zero-calorie beverages such as black coffee and tea are permitted (not fizzy drinks). During your eating periods, “eating normally” does not mean going crazy. You are not likely to lose weight, or get healthier if you pack your feeding times with high-calorie junk food, fried items and treats. The Mediterranean diet is a good blueprint of what to eat, whether you’re trying intermittent fasting or not. You can hardly go wrong when you pick complex, unrefined carbohydrates such as whole grains, leafy greens, healthy fats and lean proteins.
Before you try intermittent fasting
Intermittent fasting is generally considered safe. However, it is best to use caution when beginning or following the eating routine. Restricting your calorie intake for an extended period of time is not recommended for:
· children and adolescents
· people who are pregnant or breastfeeding
· people who have diabetes, especially type 1
· people taking certain medications
· people with a history of eating disorders
· Before embarking on intermittent fasting, consult a trusted healthcare professional to help you get started safely.