Intermittent fasting has become one of the most popular nutrition and diet trends in recent years. Its supporters claim that this approach can help with weight loss, improve blood sugar regulation, and even slow down the aging process.
This topic has now turned into one of the most frequently asked questions about nutrition. Almost every week, I receive inquiries from people who want to know my opinion about intermittent fasting. I have addressed this subject before and discussed the potential health effects of fasting. However, scientific research conducted over the past decade has made it possible to approach this topic in a more systematic and in-depth way.
Where did the scientific interest begin?
The first studies on intermittent fasting conducted in 2010–2011 were mainly carried out on animal models, especially rodents. These studies suggested that intermittent fasting may:
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reduce the risk of diabetes,
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prevent weight gain,
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decrease DNA damage,
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slow down certain biological processes associated with aging.
Although these results were promising, they were still at an early stage. Nevertheless, the findings generated widespread interest, and many people began experimenting with various forms of intermittent fasting on themselves. As a result, numerous positive personal experiences (anecdotal reports) emerged.
In recent years, more rigorous and controlled studies have been conducted—this time involving real human participants.
What does intermittent fasting mean?
Before moving on to the latest scientific findings, it is important to clarify some basic concepts. Intermittent fasting is not a single diet but rather a broad umbrella term that includes several different approaches. These approaches generally fall into two main categories:
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alternate-day fasting,
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time-restricted eating.
Alternate-Day Fasting
Alternate-day fasting involves alternating between days of eating normally (or more) and days of eating very little or nothing at all.
There are several variations of this method:
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some protocols involve complete fasting on fasting days;
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other versions recommend consuming approximately 25–50% of normal calorie intake on fasting days;
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on “feast days,” normal or slightly increased food intake is allowed.
This approach is sometimes described as calorie cycling.
The ratio of fasting days to eating days may also vary:
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daily alternation between fasting and eating,
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or the more popular 5:2 diet, in which fasting is practiced on two non-consecutive days per week, while normal eating occurs on the remaining five days.
Time-Restricted Eating
Another widely practiced form of intermittent fasting is time-restricted eating. In this approach, the focus is not so much on how much you eat, but on when you eat.
There are several models within this approach:
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eating once per day (for example, within a 4-hour eating window),
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consuming 2–3 meals within an 8-hour window,
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using a wider 10-hour eating window.
In fact, many people who skip breakfast are unknowingly already following this model.
Why does meal timing matter?
Considering our circadian rhythms (biological clock), eating earlier in the day may be metabolically more favorable. However, due to real-life conditions and social rhythms, most people find it more practical to place their eating window in the second half of the day.
Conclusion
Intermittent fasting is not a single method but a flexible approach with multiple variations. Its effectiveness may depend on:
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an individual’s lifestyle,
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metabolic condition,
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quality of nutrition,
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and long-term adherence.
For this reason, there is no universal solution—intermittent fasting should be approached thoughtfully and tailored to the individual.