Our ancestors – early hunters and forest gatherers – often went hungry. Their ability to obtain food depended on how successful they were at hunting, fishing, berry picking, and mushroom gathering. With the development of agriculture, dietary habits changed, and another significant shift occurred when many people began living in cities. For example, dinner time shifted to late evening – this happened for convenience, as it was the time when people could eat after work.
Today, when food is abundant, we rarely fast or go hungry for extended periods, except when we want to lose weight or do so for religious reasons. Many people now commonly eat four or more times a day, with the most calories consumed late in the day. Snacking frequently is also common. Many do this at least once every 15 hours, writes “Science Alert.”
Science has long proven that what and how much we eat greatly affects our health. However, recent studies have identified another criterion – the time of day when we eat.
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“What am I doing wrong?”: I eat less, but the scales seem stuck – always showing the same
To always feel productive: the best time to go to bed and wake up
Our body’s “clock” controls more than just sleep
Our internal biological clock, or circadian clock, regulates many aspects of our physiology and behavior. It signals us to be alert and active during the day and to rest and sleep at night. It can also indicate the best times to eat.
Research shows that our body is biologically prepared to receive food during the day. Digestion, nutrient absorption, and energy metabolism are optimized to occur when we should be active and eating.
When we do not follow this natural routine of our body, i.e., eating when we should be sleeping and/or fasting, we can harm our health. Improper eating habits, including eating late at night, are linked not only to weight gain but also to a higher risk of metabolic diseases. For example, shift workers, as well as people working evening, night, or rotating shifts, have a higher risk of obesity, heart disease, and diabetes. However, choosing a diet aligned with the circadian rhythm can reduce this risk, writes “Science Alert.”
Can intermittent fasting help?
Nutritional interventions increasingly focus not only on what we eat but also on when we eat. Intermittent fasting is one way to limit eating time rather than content.
There are several types of intermittent fasting, one of which is time-restricted eating. With this method, all daily calories should be consumed consistently within 8-12 hours or even a shorter time frame.
Although the media and social networks are full of success stories where people share good results, science still knows little about how intermittent fasting affects the human body.
As “Science Alert” writes, most of what we know about intermittent fasting and time-restricted eating today comes from studies with mice, which show that these dietary methods are very beneficial for weight loss and overall health.
However, it should be remembered that some aspects of mouse physiology differ from humans. For example, mice need to eat more frequently than humans, and even a short fasting period has a greater physiological impact on mice.
Mice lose 10% of their body weight in one day of fasting, while humans would need to fast for 14 days to achieve similar results.
Although there are studies showing that the health benefits of intermittent fasting and time-restricted eating have been observed in humans, the results related to weight loss are not so clear. Current data show that people following these diets lose little weight, if any, compared to calorie-restriction diets.
What has been discovered?
Drawing final conclusions about humans can be more difficult due to small sample sizes, individual metabolic differences, differences in study design (for example, different protocols with varying food restriction times and durations), and because participants do not always follow instructions, scientists emphasize.
According to scientists, most studies describing the health benefits of time-restricted or intermittent fasting also found that calorie intake was restricted: by shortening the time during which food can be consumed, people indirectly eat less.
In studies where calorie intake was controlled, intermittent fasting was not found to be more beneficial than calorie restriction alone.
It is likely that the weight loss and health benefits observed with intermittent fasting are related to reduced calorie intake. Similar conclusions were drawn regarding time-restricted eating.
“Nevertheless, time-restricted eating provides additional health benefits, such as improved glucose metabolism and blood pressure, even if calorie intake does not differ, especially if eating occurs early in the day (i.e., eating for six hours and having dinner before 3 p.m.),” write the authors of the “Science Alert” article, Frederic Gachon, Associate Professor of Circadian Physiology at the Queensland University Molecular Biology Science Institute, and Meltem Weger, Postdoctoral Researcher at the Queensland University Molecular Biology Science Institute.
According to them, one idea is that early food intake aligned with our circadian rhythm helps synchronize our circadian clock. This restores the rhythm of our autonomic nervous system, which regulates important functions such as breathing and heart rate, so that our physiology remains “tuned.”
