Intermittent fasting can boost your health, but how and when you restrict food intake is crucial

On top of starting a new exercise regimen, the new year is traditionally a time when many people rethink their eating habits. In recent years, intermittent fasting has become a popular habit — and it has some health benefits, whether it’s for control OverweightAnd chronic diseases or Low energy levels. But what exactly is intermittent fasting? And does all the hype surrounding it stand up to scientific scrutiny?

The term intermittent fasting covers several methods, each based on different principles. It’s important to note that no matter which method is used, the restrictions only affect food — not water — at all.

Eat Stop Eat, 5:2 and Time Limit are the three most popular intermittent fasting methods
A summary of the different methods of intermittent fasting. Anouk Charlotte

Science rule?

Results vary depending on the strategy adopted.

With the Eat Stop Eat approach and the 5:2 ratio, relatively few scientific studies have been done. What little data we have has shown that it works Help us lose weight And Improve some metabolic parameters such as fasting blood glucose. For example, nutritionist Surabhi Bhutani explained that using the 5:2 method for three months resulted in: Weight loss of 3-6 kilograms in participants.

However, both of these methods are very limiting and can cause Side effects On days of complete fasting or severe calorie restriction – hunger, negative effects on mood, and risk of developing hypoglycaemia.

In the long term, restriction also increases the risk of developing or exacerbating an eating disorder Yo-yo dieting. These patterns often appear after an individual attempts to lose weight by limiting himself: despite initial progress, deprivation is likely to lead to frustration that encourages The return of old eating habits.

The most studied method is the one that eats food daily but is limited in time. Two “time periods” are often observed:

  • When eating begins with breakfast and ends in the late afternoon, known as “early restricted feeding,”

  • When eating begins with lunch, known as “late feeding.”

This approach appears to improve metabolic regulation and reduce the risk of metabolic disease. However, these benefits vary according to the chosen time period. Studies have noted when he starts eating in the morning Weight loss And Improvements in insulin sensitivity.

Conversely There are fewer or no benefits To start meals in the middle of the day and finish them in the evening. As demonstrated by the team of Ram Babu Singh (Halberg Hospital and Research Institute, India) Positive results in participants who ate only in the morning – And I have no one to eat in the evening after eight in the evening

Why this difference?

Research suggests that our internal clock and circadian rhythms may have something to do with it. In fact, the benefit of eating only in the morning is that our eating and fasting periods sync up with our biological clock.

in our area previous articleWe explained that in response to light cycles, our bodies produce hormones in a cyclical fashion to adapt what we eat to the body’s energy needs: thus the optimal period for eating is from about 8 or 9 am (when the sun is shining) to 7 am. p.m. (when the sun begins to set, depending on the season).

Not eating breakfast and eating after 7 pm upsets circadian rhythms Increases the risk of metabolic diseases.

However, while eating for a limited period of time appears to be a good approach for metabolic health, Much remains to be understood about how it works and how to improve its effects. Show action in 2022 No difference in terms of weight loss Choose between eating early in the morning or late. However, it did have an effect on appetite during the day – this time in favor of the former.

And beyond the time when it seems best to eat, there may be other factors at work that aren’t always measured in the studies that have been done: the quality and quantity of food absorbed, and the length of the fasting period (which can extend from 12 to 20 hours a day). , etc. It is also worth remembering that everyone has their own metabolism and may respond differently to fasting. Therefore, new, more controlled, and comprehensive studies are needed to confirm the potential benefits of these approaches and to understand the mechanisms involved in their effects.

In practice, what do you do?

It appears that the most appropriate way to avoid disrupting an individual’s circadian clock (and thus reduce the risk of depression or eating disorders) is to eat for a limited period of time by synchronizing meals with circadian rhythms.

Thus, a typical day can be organized with a hearty breakfast in the morning between 6 and 8 am, lunch at midday and finally dinner being served between 4 and 6 pm, depending on the season.

It is not necessarily easy to come to terms with social life. Doing intermittent fasting for the family can be complicated, when one engages in physical activity in the early evening or when one works in the evening until 7 or 8 pm

One solution is to choose a large breakfast rather than a high-calorie meal in the evening – preferably without carbohydrates or sugars, so that one does not risk shifting the biological clock.

A reminder of what practices to favor and avoid
The usual day and foods should be preferred to practice eating for a limited period of time. Anouk Charlotte

Chronic feeding

Intermittent fasting is increasingly popular and intermittent fasting appears to actively promote metabolic health. However, as we have seen, it is not a panacea. And we must make sure that the periods of fasting and eating correspond to our biological clock.

Faced with many current approaches, and potential risks, patients and health professionals continue to face a lack of information. More research is necessary to better understand its effects. Currently, there is no general consensus on the ideal time to eat/fast or on the optimal duration of each period. Moreover, these criteria may vary from person to person, depending on genetic makeup, history, and lifestyle. It is therefore important to consider the use of this dietary strategy with qualified health professionals, with the aim of establishing a healthy and balanced diet that will reduce the risk of complications.

Anouk CharlotteDoctor, University of Strasbourg And Joffrey ZollMCU-PH in Physiology, School of Medicine, University of Strasbourg

This article has been republished from Conversation Under Creative Commons Licence.

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