What is intermittent fasting (IF)?
Refers to a dietary plan where you alternate periods of eating with periods of fasting.
When we fast - our body switches from utilising sugar and carbohydrate from the food we eat to utilising fat stored in our body as an alternative source of energy - hence burning fat and reducing obesity.
Intermittent Fasting Benefits
1) Help in weight loss and combating obesity
- Studies have demonstrated that Intermittent fasting can help reduce 3-8% of weight over 24weeks.
- It can also help to reduce waist circumference by 4-7%.
2) Improve hypertension and hyperlipidemia and reduce risk of heart attack and stroke.
3) Manage diabetes by reducing insulin-resistance and inflammation.
4) Improve cognitive function like memory, executive function and global cognition.
However there are certain groups of patients which are not suitable for IF
- Growing children less than 18 years old
- Pregnant ladies and mothers who are breast feeding
- Underweight patients and patients with eating disorders
- Diabetic patients who have volatile sugar levels and are on diabetic medications
3 most widely studied intermittent fasting plans are :
- Alternate-day fasting : Eat for one day and fast for the next.
- 5:2 fasting where you eat 5 days a week and fast 2 days a week where you only eat within a window of 4-8 hours a day.
Which type of intermittent fasting will work for you?
Some people can actually tolerate going a full day without food , so alternate day fasting or 5:2 fasting may be suitable.
Some people cannot tolerate going without food for the day - hence they do time restricted feeding where they will designate certain timing of the day to have their food.
One of the most popular daily time restricted feeding plan is a 16:8 plan.You can eat your meals within a 8 hours window and fast the next 16 hours.
For example, you can have your breakfast at 9am , lunch at 12noon and finally dinner at 5pm. ( 8 hour window )
Is there a best time of the day to eat?
There is a circadian system within our human body that determines the metabolism in a 24 hour cycle.
Glucose, insulin, lipid levels, energy expenditure and appetite peaks in the morning to afternoon period – indicating morning to afternoon as an optimal period to eat.
By using the 16 : 8 plan and shifting to a morning to afternoon feeding window, it may help in more effectively :
- lowering blood pressure
- lowering post meal insulin levels and improving insulin sensitivity
- reduce appetite in the evening
- reduce oxidative stress
Can Intermittent fasting help with effective weight loss?
- Not everyone is able to endure starvation.
- If you do follow the 16:8 rule but you take a lot of fried fatty food and candies with sweet soft drinks during that 8 hours period, then it would not have any benefits on your health. A wholesome healthy diet is still important.
- For effective weight loss - you will have to combine physical activities and exercise with the diet. Weight loss is always 70% diet and 30% exercise.
- There are patients with medical conditions always check with your physician or doctor for approval before you embark on intermittent fasting.
By : Dr Chen Yiming
Family Physician, MBBS (Singapore), GDFM (NUS), GDFP Dermatology (NUS)