Intermittent fasting is an alternative diet that is becoming increasingly popular. It typically involves a repetitive and intentional restriction of caloric intake or "fasting" over a period of time interspersed with periods of unrestricted eating.
For instance, Time Restricted Feeding refers to fasting for a period of at least 14 hours daily and eating as usual within the remaining hours of the day (feeding window).
Some other types of intermittent fasting that do not involve a defined period of prolonged fasting include alternate day fasting where you fast on one day, alternating with eating as usual the next day, and the 5:2 diet where you would fast for two days of the week, on consecutive or non-consecutive days, and eat as usual for the remaining five days of the week. On the day of fasting, you can consume up to 25% of your caloric requirements.
"The most common health benefit is weight loss that may be accompanied with improved blood test results, cholesterol levels or blood pressure. Certain body functions are also enhanced, including increased insulin sensitivity and glucose regulation, reduced oxidative stress and inflammation, improved cognitive function, as well as protective effect against neurodegenerative diseases," says SKH dietitian Alexis Ng. "It's important to note that these benefits were seen in study participants who followed a well-designed, safe intermittent fasting regime while being closely monitored by healthcare professionals. Intermittent fasting could potentially cause more harm than good if done without proper guidance," she adds.
Intermittent fasting, when practised using the principles of a healthy, balanced diet, can lead to weight loss. To promote weight reduction, the body needs to achieve a state of net negative calorie balance that can be contributed from a reduction in calorie intake and/or an increase in calorie output via exercise.
On fasting days, individuals are either only allowed to consume a restricted amount of calories or would generally consume lesser calories than usual, thereby contributing to a daily net caloric deficit.
Due to the nature of the diet which involves fasting and restrictions of food intake, there are health risks and implications.
Mild side effects include the inability to focus, giddiness, headache, nausea, vomiting, diarrhoea and temporary sleep disturbances. More serious consequences include large fluctuations in blood glucose levels, dehydration, nutrient deficiencies and muscle loss. Intermittent fasting has not been shown to be superior in weight loss effectiveness when compared against daily caloric reduction with regular, balanced meals.
If you want to take on intermittent fasting, you must first consider your medical condition(s) and seek professional advice.
Intermittent fasting is NOT suitable for (this list is not exhaustive):
• Children under 18 years old
• Pregnant or breastfeeding mothers
• People with eating disorders, uncontrolled diabetes, cognitive impairment, or are immunocompromised
• People with daily fluid intake restrictions
• Patients who have undergone bariatric surgery
It is important to have a balanced meal during your feeding windows on fasting days. Include a variety of food from all food groups to prevent vitamin and mineral deficiencies.
Eat mindfully Take time to savour each bite and chew your food slowly instead of gobbling down your meal. Avoid snacking between meals.Stay hydrated Drink plenty of non-calorie-containing fluids during fasting and feeding windows to prevent dehydration and headaches.Quality, not quantity Do not compensate and eat excessively during non-fasting days and feeding windows. Limit the intake of high-fat, high-refined-sugar food and beverages.Keep your mood and energy levels in check Fasting may affect hormone levels, leading to increased irritability. It can also affect energy levels, which is dangerous especially if driving or operating machinery. Remember to regularly follow up with your doctor or dietitian!
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