Dear Wellness Seeker,
Intermittent fasting (IF) is a pattern of eating that alternates between eating and fasting. In that sense, everybody practices intermittent fasting! Most people refer to IF as an eating pattern that extends the length of time they spend in the fasted state (i.e. when food from the previous meal has been absorbed and processed).
Time-restricted eating is a popular approach and is commonly used with a 16:8 pattern, i.e. 16-hour fast and 8-hour eating window. This is typically achieved by skipping or delaying breakfast but could also be done by consuming dinner earlier in the day. Other IF protocols include: the 5:2 diet (consuming only 500 kcal two days per week) or alternate-day fasting.
Is there a method to favour among its variants?
Both the 5:2 diet and alternate-day fasting prescribe calorie deficits, whereas time-restricted eating does not. Despite this, research shows that free-living individuals tend to spontaneously reduce their energy intake when their daily eating window is limited. Thus, all IF protocols should lead to weight loss, at least in the short-term, particularly if you are currently overweight.
Many people adopting time-restricted eating find skipping breakfast easier to adhere to and less disruptive to social occasions, such as eating dinner together with the family. However, preliminary research indicates that shifting energy intake to earlier in the day may promote additional benefits for metabolism. This is likely due to diurnal rhythms in metabolic responses to nutrients, for instance, we are more efficient at processing glucose in the morning than the evening.
Ultimately, it is an individual’s personal choice to pursue an IF protocol that is compatible with their own lifestyle and aligns with their health goals.
What are the main benefits of IF?
A primary benefit of IF is weight loss due to consuming fewer calories. During fasting, the release of the hormone insulin is suppressed and fat burning is increased. Since weight loss itself has independent benefits on metabolism the effects of IF need to be examined against a (calorie-matched) control group that does not alter their eating patterns. Early research suggests the benefits of some IF protocols are, at least partly, independent of energy balance.
A major benefit of IF is an improvement in insulin sensitivity, which is a key predictor of future cardiovascular disease risk. Fasting also upregulates autophagy, a process involving degradation and recycling of cellular material. This can help to reduce levels of inflammation and oxidative stress, high levels of which are risk factors for several chronic diseases.
Another appealing aspect of IF to individuals who have struggled with their weight is the more simplistic and easier to follow message than more traditional dietary approaches such as calorie counting. The long-term feasibility of IF versus these methods will ultimately determine the suitability of this eating pattern.
How to start? And precautions to take?
At first, you could try to gradually extend the length of your overnight fast, for instance by cutting out evening snacks, before progressing to a more structured regime. Many people find sparkling water beneficial when dealing with hunger during fasting.
Imposing severe calorie restrictions and regularly undergoing prolonged (>24h) fasts are generally not recommended due to the associated increase in proteolysis (the breakdown of muscle).
How often shout it be practised to observe benefits?
Studies in rodents have shown that the metabolic benefits of IF persist when unrestricted food access is permitted at the weekend. This could alleviate the social burden of IF and facilitate greater adherence. Another interesting question is how long the benefits of IF persist after returning to a more typical pattern of eating. Hopefully, further research will soon be emerging to guide practical strategies for IF.
To your Best Life,
Dr Robert Jones
Your Chenot Wellness Team