The phrases “time-restricted eating” and “intermittent fasting” are often used interchangeably, and a common misconception is that they are both the same.
Although both strategies focus on the principle of controlling when you eat, they differ in terms of methodology, flexibility, and potential health benefits.
Time-restricted eating (TRE) is focused on limiting your eating window every day, while intermittent fasting (IF) typically involves alternating between periods of eating and fasting.
Think of it this way: TRE is a type of intermittent fasting, but not all IF protocols are time-restricted eating. You can also look at our keto vs intermittent fasting post where this is discussed further.
Let’s take a closer look at the differences between these two strategies and see which one may best suit your lifestyle and goals.
Is There a Difference Between Time-Restricted Eating and Intermittent Fasting?
Yes, there is a difference between time-restricted eating and intermittent fasting. Firstly, their names are a dead giveaway (one is all about eating, while the other is about fasting).
If you think about it, they are two sides of the same coin. It’s all about controlling when you eat, but the approach and duration of time both vary.
Let’s now examine the differences between intermittent fasting and time-restricted eating.
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Time-Restricted Eating (TRE)
Time-restricted eating involves limiting your daily eating window to a specific number of hours.
For example, you may choose an eight-hour eating window each day and fast for the remaining 16 hours. This approach is sometimes referred to as 16:8 fasting and is one of the most popular forms of TRE.
Other variations include a 12, 10, six, or four-hour eating window, with the remaining hours being fasting periods.
The primary goal of TRE is to align your eating schedule with your natural circadian rhythm, which follows a 24-hour cycle and is influenced by light and dark cues.
By restricting your eating window, your body is given more time to rest and repair during the fasting period, which is believed to result in potential health benefits (3).
What Happens to Your Body When You Do Time-Restricted Eating?
Research focused specifically on time-restricted eating benefits is still quite limited, but some tentative conclusions can be drawn from studies on intermittent fasting in general. Again, it’s important to remember that TRE is just one form of intermittent fasting, and different protocols may yield different results.
Some potential benefits of time-restricted eating include:
Improved Insulin Sensitivity
By giving your body a break from constant food digestion, TRE may improve how your cells respond to insulin, the hormone that is responsible for regulating blood sugar levels. This can be beneficial for those with insulin resistance or prediabetics (3).
Lower Inflammation Levels
Chronic inflammation has been linked to a variety of health issues, such as heart disease and cancer. Some studies have found that TRE may help reduce markers of inflammation in the body (3).
By limiting your eating window, you may naturally consume fewer calories, which will lead to weight loss over time. However, it’s important to note that calorie intake still matters, and TRE alone may not result in weight loss if you consume more calories than your body needs.
Furthermore, a combination of time-restricted eating and exercise may be necessary to achieve the best outcome (3).
Potential Longevity Benefits
Some animal studies have suggested that intermittent fasting, or calorie restriction in general, may have anti-aging effects and could potentially extend lifespans (1). However, more human research is required to determine if this also applies to people.
The side effects of time-restricted eating may be quite similar to those of intermittent fasting in general. For some people, a restricted eating window can lead to initial hunger and discomfort until the body adjusts to the new schedule.
In addition, depending on your specific protocol and what you eat during your eating window, you may experience nutrient deficiencies or low energy levels if you don’t consume a balanced diet.
Intermittent Fasting (IF)
At the same time, intermittent fasting encompasses a broader range of eating protocols. It typically involves alternating between periods of eating and fasting, with different durations for each phase. For example, some popular IF approaches include:
- 5:2 – five days of normal eating and two non-consecutive days of significant calorie restriction (approximately 500-600 calories)
- Alternate-Day Fasting – alternating between a day of eating and a day of fasting
- Eat-Stop-Eat – one or two full-day fasts per week, with the remaining days being regular eating days
The duration of fasting periods in IF can vary from a few hours to multiple days. However, most protocols recommend a fasting period of at least 16 hours in order to improve the odds of achieving potential health benefits.
What Happens to Your Body When You Do Intermittent Fasting?
Research on IF benefits is much more extensive than research on TRE, and many of the potential benefits mentioned earlier also apply to IF. In addition, intermittent fasting may help with:
Improved Cardiovascular Health
Some research suggests that IF may help improve some markers of cardiovascular risk, including blood lipid levels and blood pressure. This could be due to a combination of weight loss and reduced inflammation (2).
Improved Brain Function
Some research has suggested that intermittent fasting may improve cognitive function and protect against certain neurological diseases (2).
The side effects of intermittent fasting may also be similar to those of TRE, depending on your specific protocol. However, as IF involves longer periods of fasting, you may experience more significant hunger or discomfort initially until your body adapts (2).
Knowing what to eat during intermittent fasting can significantly impact your experience and we have a comprehensive guide to that too.
Do You Lose Weight Faster by Fasting or Restricting?
There is no clear answer to the issue of intermittent fasting vs time-restricted eating for weight loss as it is ultimately dependent on a variety of factors, including individual body composition and eating habits.
However, logic suggests that intermittent fasting may lead to slightly faster weight loss in comparison to time-restricted eating.
This may be due to the longer periods of fasting in IF, which can result in a greater calorie deficit over time. We offer further explanation of this in our article on types of fasting.
You should consider these factors that may further impact weight loss with time-restricted eating or intermittent fasting:
- Calorie intake: Both TRE and IF can lead to weight loss by creating a calorie deficit, which means that you consume fewer calories than your body needs.
However, if you consume more calories than your body needs during your eating window, weight loss may not occur.
- Exercise: Although TRE and IF do not require any specific exercise, incorporating physical activity will further enhance weight loss results.
- Current weight and body composition: Depending on your starting weight and body composition, you may see faster results with either TRE or IF.
For example, someone with a higher body fat percentage may see quicker weight loss through either protocol as they have more excess weight they need to lose.
- Health conditions: Certain health conditions may impact weight loss results with TRE or IF, including hormonal imbalances and underlying medical issues.
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Is Fasting or Restricting Better?
The truth is that although there are a few documented health benefits, there isn’t enough research to prove whether TRE or IF is best. The majority of studies have been conducted using animal subjects and only a small percentage of them have involved humans.
Both approaches can also potentially help with weight loss and improved overall health, and the decision comes down to which protocol you’re more likely to be consistent with.
Most diets don’t fail because they are ineffective, but because people can’t stick to them. Therefore, it’s best to choose a form of intermittent fasting you enjoy and can incorporate into your lifestyle in the long term.
Precautions and Considerations
Before you start any new eating regimen such as time-restricted eating or intermittent fasting, it’s essential that you consult with your healthcare provider. They can help you determine whether it’s safe for you, particularly if you have underlying health conditions or are taking any medications.
Furthermore, there are some groups of people who should avoid or approach intermittent fasting with caution, such as pregnant or breastfeeding women, those with a history of eating disorders, and those with certain medical conditions (e.g., diabetes).
In addition, children and teenagers should not do any form of fasting without medical supervision.
We believe that TRE and IF are not a quick fix for weight loss or overall health. Both approaches require dedication, consistency, and a well-rounded approach to nutrition and exercise if you want to achieve optimal results. You should focus more on building healthy habits rather than having a sole reliance on time-restricted eating or intermittent fasting to achieve your health goals.
Frequently Asked Questions
Do I need to count calories on 16:8?
Although it is not strictly necessary, calorie counting can be helpful when you follow the 16:8 intermittent fasting schedule. This approach involves fasting for 16 hours and eating within an eight-hour window.
While the primary focus is on the timing of meals, maintaining a balanced diet and keeping an eye on your calorie intake can help support weight loss and your overall health goals.
Is 12 hours between meals considered intermittent fasting?
Yes, 12 hours between meals can be considered to be a form of intermittent fasting and is specifically known as the 12:12 method.
This is one of the more flexible fasting protocols where you fast for 12 hours and eat within a 12-hour window. It’s seen as a gentle introduction to intermittent fasting and can still offer certain health benefits.
Is 16:8 the only form of intermittent fasting?
No, 16:8 is just one intermittent fasting method. There are various other methods, including 5:2, where you eat normally for five days and restrict calories for two non-consecutive days, and alternate-day fasting, where you fast every other day.
What is the most effective time-restricted eating method?
Research has found there to be promising results with the 16:8 method. This involves fasting for 16 hours and eating within an eight-hour window, often aligning eating periods with the body’s natural circadian rhythm. That being said, the method that fits best into your lifestyle and that you can stick to is the one that will prove to be the most effective for you.
The Bottom Line
Although there is a certain amount of overlap between time-restricted eating and intermittent fasting, they are not exactly the same. The main difference is that TRE is focused on a daily restricted eating window, while IF involves alternating between periods of eating and fasting.
Both approaches have the potential to promote a variety of health benefits, but it’s important to find what works best for your body and lifestyle.
This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!
- Intermittent and periodic fasting, longevity and disease (2021,nih.gov)
- Research on intermittent fasting shows health benefits (2020,nih.gov)
- Time-Restricted Eating: Benefits, Mechanisms, and Challenges in Translation (2020,nih.gov)