Each of these time-based eating/fasting methods has been studied to varying degrees, and their effects can vary based on numerous factors, including the individual’s overall diet, physical activity level, and metabolic health. Below is a summary from researching this list of studies. More research is needed to fully understand their long-term effects and potential benefits:
Time-based Eating Options
The following time-based easting options are the most reported on in the scientific literature.
Time-Restricted Feeding (TRF): With TRF, individuals consume all their daily calories within a specified timeframe, often 8-10 hours, and fast for the remaining 14-16 hours. Variations can include 16/8 (16 hours of fasting, 8 hours of eating), 18/6, or 20/4. Some studies suggest TRF may aid weight loss and improve metabolic health.
Alternate-Day Fasting (ADF): This method alternates between ‘fast’ days, where very few calories are consumed (often 500 or less), and ‘feast’ days, where individuals can eat whatever they like. Some research suggests ADF can lead to significant weight loss and health improvements, but adherence may be challenging for some people.
5:2 Diet: On this regimen, individuals eat normally for five days of the week and drastically reduce calorie intake (often to around 500-600 calories) for the remaining two days. Studies have found this method can lead to weight loss and improved metabolic health.
Periodic or Prolonged Fasting: This involves fasting for extended periods, typically 24-48 hours or more, less frequently, such as once a week or once a month. This approach has been studied less than daily intermittent fasting methods, but preliminary studies suggest potential benefits for weight loss and metabolic health.
Eat-Stop-Eat: This method involves one or two non-consecutive 24 hour fasts in a week, with normal eating on the other days. It’s similar to periodic fasting but has specific fasting days.
Fasting Mimicking Diet (FMD): Developed by Dr. Valter Longo, this diet involves consuming a very low calorie, low protein, high fat diet for five days, followed by 25 days of unrestricted eating. Preliminary research suggests it may offer some of the same benefits as more prolonged fasts, but with fewer risks.
Most Studied Time-based Eating
Among the studies provided, the most commonly studied types of intermittent fasting are Time-Restricted Feeding (TRF) and the 5:2 Diet, based on the frequency of these protocols in research.
- Time-Restricted Feeding (TRF): Several studies have focused on TRF, making it one of the most popular forms of intermittent fasting in research. For instance, Sutton et al. (2018) studied early time-restricted feeding, while Gabel et al. (2018) evaluated the effects of 8-hour TRF on body weight and metabolic disease risk factors in obese adults.
- 5:2 Diet: The 5:2 diet has also received considerable attention in research. Harvie et al. (2011) studied the impact of intermittent energy and carbohydrate restriction v. daily energy restriction on weight loss and metabolic disease risk markers in overweight women.
Studies on Alternate-Day Fasting (ADF) are also relatively common but not as much as TRF and the 5:2 diet. Other fasting methods like Periodic or Prolonged Fasting, Eat-Stop-Eat, and the Fasting Mimicking Diet (FMD) have been the subject of fewer studies.
It’s important to note that while these types of fasting methods are more frequently studied, it doesn’t necessarily mean they’re more effective. The results vary significantly among individuals, and the optimal fasting method may depend on numerous individual factors, including lifestyle, dietary preferences, and specific health goals. More research is needed to understand the best approach for different individuals and populations.
Least Studied Time-based Eating
From the set of studies provided, the least prevalent types of intermittent fasting studied appear to be the Fasting Mimicking Diet (FMD), Periodic or Prolonged Fasting, and the Eat-Stop-Eat approach. These methods are less represented in the literature than others, such as Time-Restricted Feeding (TRF) and the 5:2 Diet.
- Fasting Mimicking Diet (FMD): The FMD is a plan that significantly restricts calorie intake for a certain number of consecutive days each month, while allowing normal eating during the rest of the month. This protocol was pioneered by Dr. Valter Longo, and a notable study is the one conducted by Choi et al. (2016), which looked at the effects of the FMD on markers of aging, diabetes, cardiovascular disease, and cancer in mice, with some preliminary results in humans.
- Periodic or Prolonged Fasting: This involves abstaining from food for extended periods (e.g., 24-72 hours), usually done less frequently (for example, once a month). One of the rare studies on this type of fasting is by Brandhorst et al. (2015), exploring the impact of prolonged fasting on stem cells and regenerative capacity in mice and human cells.
- Eat-Stop-Eat: This approach involves a 24-hour fast once or twice a week. It’s less commonly studied, with no specific studies from the supplied set directly investigating this approach.
It’s important to note that the lesser prevalence of these methods in research does not necessarily reflect on their effectiveness or suitability for different individuals. Different fasting methods may be more or less appropriate depending on individual health status, lifestyle, and goals. More research is needed on these less-studied methods to understand their potential benefits and drawbacks fully.
