Does it matter what time of day you eat?

Review: Here’s what science says about improving your health with intermittent fasting and meal planning

By Frederic Gachon and Meltem Weger, University of Queensland

Early hunters faced long periods of fasting. Finding their food depended on successful hunting, fishing and the availability of wild plants. Over time, the development of modern agriculture and the transition to advanced industrial societies changed our regular eating habits, changing our dinner time to later. per day to accommodate working hours.

Today, with access to more food, we rarely have long periods of fasting, except for weight loss or religious practices. It is now common to eat four or more meals a day, with most calories eaten later in the day. Frequent eating is also common, with a window of about 15 hours.

However, more and more research shows that our health is not only affected by what we eat and how much we eat, but also when we eat. So what does this mean in terms of diet? And can intermittent fasting help?

Our body clock controls more than our sleep

The internal biological timekeeper, or circadian clock, controls many aspects of our physiology and behavior. It tells us to be alert and active during the day, and rest and sleep at night. It can also tell us the best time to eat.

Our body is designed by nature to receive food during the day. Digestion, nutrient absorption and energy metabolism are optimized to occur when we need to be active and eat.

Working against this regular step, by eating frequently when we have to sleep and fast, can endanger these processes and affect our health. Unstable eating patterns, including late night eating, are associated with weight gain and a greater risk of metabolic syndrome.

For example, shift workers, and people who work evenings, nights or rotating shifts, have a higher risk of obesity, heart disease and diabetes. But adopting an eating pattern that aligns with our circadian rhythm can reduce these risks.

So can intermittent fasting help?

Nutrition initiatives are increasingly focusing not only on “what” we eat but also “when”. Intermittent fasting is another form of time control, rather than the content of what we eat.

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From RTÉ Radio 1’s Today with Claire Byrne, how effective is intermittent fasting?

There are several types of intermittent fasting, one of which is intermittent fasting. This means consuming all our calories in a fixed period of 8-12, or even shorter periods, every day.

But is it supported by evidence? Much of what we know today about intermittent fasting and restricted eating comes from rodent studies, which show weight loss and health benefits associated with these types of diets.

However, some aspects of mouse physiology may differ from humans. Mice need to eat more frequently than humans, and even short periods of fasting have a significant physiological effect on mice. One day of fasting in mice leads to a 10% weight loss, while humans would need to fast for 14 days to get the same results. This makes direct translation from mice to humans more difficult.

While the health benefits of intermittent fasting and timed eating have also been noted in humans, research on weight loss is less clear-cut. Recent data suggest only modest, if any, weight loss in participants with these diets compared to low-calorie diets.

Drawing clear conclusions in humans may be more difficult due to small sample sizes and metabolic differences, differences in study design (such as the use of different protocols at different times and duration of food), and participants who do not follow their instructions. .

Health benefits can come from eating fewer calories

Many studies that describe the health benefits of intermittent fasting or intermittent fasting have also found that these diets were accompanied by calorie restriction: limiting the amount of time you have access to food makes that people eat less.

Studies that controlled calorie intake found no additional benefits of intermittent fasting beyond calorie restriction alone. The weight loss and health benefits observed with intermittent fasting can be attributed to a reduction in calorie intake. Similar findings have been reported for timed eating.

The benefit of following our body clock

However, timed eating provides other health benefits in humans, such as improved glucose metabolism and blood pressure, although there is no difference between eating a diet with ‘halori, especially in the early part of the day (that is, during the six hours. eating window with dinner before 3pm).

Restricting food intake during the day for shift workers can reduce metabolic differences caused by shift work, whereas this effect is not observed when food is restricted only at night.

Another theory is that eating earlier, based on our circadian rhythm, helps align our circadian clock. This restores the rhythm of our autonomic nervous system, which controls vital functions such as breathing and heart rate, keeping our physiology “permissive”, as shown in mice.

Although there is still much to be learned from research in this area, evidence suggests that for weight maintenance and overall health, the goal of eating a diet that contains and proper nutrition during the day, while avoiding late night eating and frequent snacking.

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Frederic Gachon is Associate Professor, Physiology of Circadian Rhythms at the Center for Molecular Bioscience at the University of Queensland, Meltem Weger is a Postdoctoral Research Fellow at the Center for Molecular Bioscience at the University of Queensland.. This article was originally published by The Conversation.

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The views expressed here are those of the author and do not represent or reflect the views of RTÉ

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