Is intermittent fasting effective? What time should we “break” our fast at?
Summary
Intermittent fasting is an eating pattern that focuses on when you eat instead of what you eat.
The most common structure of an intermittent fasting eating pattern is known as the 16/8 pattern where you would eat within an 8 hour window and fast for 16 hours. There are other intermittent eating patterns such as alternate day fasting, but this can be more challenging to stick with. If following the 16/8 pattern, the 8 hour time frame that one eats during is up to the individual and what works best for their schedule. Many that follow the 16/8 eating pattern prefer to eat later in the day rather than earlier, for example, from 12-8pm or 1pm-9pm. This is because people tend to find it easier to skip breakfast rather than lunch or dinner, as they are more likely to go out to lunch with a coworker or to dinner with friends and family. However, research shows that eating earlier in the day may be better due to the circadian rhythm and it has been shown to improve insulin sensitivity, blood pressure, and oxidative stress levels. When choosing a window for eating and fasting, make sure that it will fit into your lifestyle in a way that feels sustainable.
The overall idea behind intermittent fasting is to reduce calories and to promote losing body fat, while decreasing the risk for chronic disease. Studies show that people eating using an intermittent fasting diet plan do lose weight, not because of the times that they’re eating, but because they’re likely eating less than they were before. For example, if someone is only eating from 12-8pm, this could cut down on night time snacking when many people tend to reach for more processed food items to wind down for the evening. Overall, compared with calorie restriction without time constraints, similar weight loss has been observed.
There are a lot of health benefits that have been noted with intermittent fasting in research studies such as weight loss, increased longevity, and reduced insulin resistance and inflammation. A few main challenges with this eating pattern is that it can be difficult to maintain over time, it can lead to increased cravings, and some people may experience irritability, lightheadedness, and fatigue. Some may find it challenging to maintain their usual social life, because if you’re someone that likes to go out to dinner with friends or family regularly, you will have to plan your eating window accordingly.
Lastly, it’s important to note that just because you’re eating during the 8 hour window doesn’t mean that you should eat anything and everything, and it is possible to miss out on getting enough nutrients due to the shorter eating window. Eating whole foods and limiting the amount of junk food consumed should remain a top priority. The likelihood will increase that one may crave high calorie/high fat items when they’re very hungry, so planning out meals ahead of time can aid in developing a healthful eating pattern window.
As always, you should talk to your doctor before considering starting a diet such as intermittent fasting, as it may not be a good approach for certain populations or those with specific health conditions.
Written By: Summer Lippert MS, RDN, LD / Implementation Manager
Disclaimer:
No content in this post, should ever be used as a substitute for medical advice from your doctor.
Resources:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7021351/