What is IER?
Weight loss occurs when energy expenditure exceeds energy intake. If you do this by reducing your total energy to 20-50% of your needs, weight loss can occur. This can be difficult to adjust to, and comply with. For some people, it can even cause side effects such as headaches, dizziness and irritability. For this reason, there is an alternative method of calorie restriction known as intermittent fasting. This is a pattern of energy restriction that might be easier to comply with for some people.
How did it come about?
The concept of intermittent fasting was first studied in rodents, where it showed promising results of improved insulin sensitivity, enhanced immunity and chronic disease prevention. Having achieved promising results in rodents, it was then studied in humans.
How does intermittent fasting work?
Basically, intermittent fasting is alternating between regular calorie consumption and a lower calorie consumption. Consumed either on different days or at different times during the day. This ensures that the body doesn’t feel like there has been a huge change in the amount of food consumed.
Different methods of intermittent fasting
- The 16/8 method: fasting for 16 hours and eating for 8 hours
- The 5/2 method: eating normally for 5 days and fasting for 2
- A 24 hour fast: 1-2 days per week
- Fasting every alternate day
- Fast in the day and eat huge meals at night
- Skip meals as per convenience
What is the difference between intermittent energy restriction (IER) and continuous energy restriction (CER)?
Intermittent fasting is proven to be effective in producing weight loss. The average amount of weight loss is reported to be 3-5kg after 10 weeks of IER. IER and CER both showed equivalent reductions in BMI (body mass index), waist circumference and hip circumference. However, it is reported that there’s a greater feeling of fullness and control of appetite with IER compared to CER. The exact mechanism for this is not known.
In summary
Both continuous energy restriction and intermittent energy restriction are equally effective for weight loss. Intermittent fasting is not superior to continuous energy restriction. However, IER for many is easier to achieve and comply with. Although credible studies have found that IER can produce the same amount of weight loss as CER in the short term, we are not aware if there is long-term maintenance with the IER approach. In fact, a study conducted found side effects in the long-term such as longer menstrual cycles with IER. It was also found that there was an increased amount of fatigue with IER compared to CER. In addition, these studies were conducted only with females and not male participants. Hence, we are unaware if IER is as effective for males as it is for females. More research needs to be conducted to explore the possible long term benefits of intermittent fasting.
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This article was written by our dietitian and nutritionist Juhi Bhambhaney. If you have any questions regarding health and nutrition, make an appointment with one of our dietitians. We‘ll provide you with a simple and effective routine targeted to your concerns. Contact us today.
