You will have most likely heard of the term intermittent fasting or have seen someone post about it on social media. It has been a topic of interest in the past couple of years, but what actually is it, and what does the evidence say? Local nutritionist Danielle Wilcock, explains the basic principle of intermittent fasting and delves into the debate surrounding its efficacy.
Danielle Wilcock, Nutritionist
www.mindbodynutr.com – @mindbodynutrition_
What is intermittent fasting?
Intermittent fasting is not a diet. It is a timed approach to eating. Unlike a dietary plan that restricts where calories come from, intermittent fasting does not specify what foods a person should eat or avoid.
There are commonly three main types of intermittent fasting and all include periods of ‘fast’ but in varying degrees and using different methods:
The first is referred to as ‘whole day fasting’ and an example if this would be the 5:2 diet. It involves 1-2 days a week where limited energy in the form of calories are consumed. On days where fasting isn’t being undertaken, no food restriction occurs.
Another intermittent fasting method includes ‘alternate day fasting’, which involves fasting on alternate days. During the fasted days most people are recommended to have only the one meal which equates to about a quarter of the daily calorific needs. This is quite an extreme method of fasting and should only be conducted by those who have obtained advice from a health professional.
Perhaps the least popular or commonly known method of intermittent fasting would be ‘time restrictive feeding’. This involves a narrowing of the time you are able to eat. For example, fasting occurs for 16 hours a day and only permits the consumption of foods during the remaining eight-hour period.
As with a lot of “fad diets” and trends, they are often marketed by social media health or fitness “experts” with little consideration for nutritional benefit or widespread efficacy.
Efficacy
Intermittent fasting may have some health benefits, including weight loss, but is not suitable for everyone and as with any diet method, supplement or diet product one must look at the research studies that support its efficacy.
In general, studies have reported some positive effects of intermittent fasting on weight loss and maintenance.
A study that featured in the European Journal of Clinical Nutrition looked at intermittent energy restriction and weight loss. The study involved measuring the weight loss of overweight and obese adults who adopted an intermittent fasting diet. They then compared these to the weight loss results from individuals who were following a normal balanced diet. They concluded that intermittent fasting may contribute to weight loss for some, but it is not superior to other diets that incorporate an overall daily calorie reduction.
Overall, the research on intermittent fasting is relatively premature and more needs to be conducted on its efficacy.
Considerations
As it stands, while some research has indicated that intermittent fasting can be effective for weight loss, it hasn’t really suggested that it is any more effective than regular balanced diet protocols.
However, it is a very restrictive protocol to adhere to and, while this will work well with some people, it certainly won’t for others.
Diets on the days that fasting are not occurring need to be extremely nutrient dense to compensate for the periods of fast.
Diets must be well balanced and rich in protein, fibre with a variety of fruits and vegetables.
Meeting fluid recommendations are also extremely important.
The pros
• Reduced levels of insulin, which promotes the body’s usage of stored fat
• Lowers blood pressure and inflammation levels
• Dramatically increases human growth hormone, or HGH, which helps the body utilize body fat and grow muscle
The cons
• Irritability and low mood due to lack of food
• Reduced energy levels due to periods of little energy intake
• Prolonged periods of fasting can lead to overeating as a consequence, which is why it may not work as a weight loss tool for all
• It is not suitable for certain populations such as pregnant women, those with eating disorders or individuals with certain health conditions such as diabetes and low blood pressure.
