“Time restricted eating” is a type of intermittent fasting. It focuses on when you eat, rather than what you eat. There is a lot of research going on regarding this approach, so let’s look at how time-restricted eating can be of benefit, and see if it might be useful for you. 

What is time restricted eating?

We all fast for several hours during the night while we are asleep. Time restricted eating (TRE) takes this one step further to add on some additional hours to that fast, beyond your period of sleep. Typically, TRE is for 12 hours or more, which means if you finish dinner at 7 pm, you don’t eat breakfast until after 7 am. Another popular TRE schedule is a 16:8 ratio of fasting to eating, so you fast for 16 hours, and then eat during an 8-hour window. For example, if you finish dinner at 7 pm, you  don’t eat again until 11 am the next morning, and your last meal ends by 7 pm – so eating in an 8-hour window. This schedule boils down to you basically skipping breakfast.  

You don’t have to worry about calorie restriction – often there will be some, but it is not a goal of TRE. Nor are there certain foods that are off-limits. The focus is purely on limiting the time period of eating.

Another good part of TRE is that this isn’t something you have to do every day to get some benefit. 

The current research interest on TRE began with looking at it as an approach for obesity and metabolic disease.

Animal studies on time restricted eating

One of the key animal studies investigated if TRE could protect mice from metabolic disease. Researchers compared feeding mice throughout the day (known as ad libitum) versus confining their food intake to a period of 8-9 hours, and fasting for the rest of the day. Their diet was a high fat, high fructose, high sugar diet. The diagram below highlights the study findings nicely.

Image depicting animal study on time restricted eating in mice, from CALMERme.com

From: Time-Restricted Feeding Is a Preventative and Therapeutic Intervention against Diverse Nutritional Challenges. Chaix, Amandine et al., 2014. Cell Metabolism, Volume 20, Issue 6, 991 -1005.

TRE was seen to stabilize and reverse the progression of metabolic disease in obese mice with type II diabetes. These findings also show that TRE can even be effective when followed five days a week, with weekends left to eat freely.  

Now, I’m not advocating that you use time-restricted eating as a cheat way to carry on eating a high fat, high fructose, high sugar diet. Rather, if TRE can keep mice lean on a bad diet, it’s got to be worth looking at what it can do for us on a better diet too. 

Human studies on time-restricted eating

Following many animal studies, human studies now also show encouraging results. TRE is now seen as a powerful tool for preventing and reversing disease. Some of the benefits seen of TRE include:

  • decrease in body weight and percentage body fat
  • reduced risk of cardiovascular disease, including reduced cholesterol levels
  • decrease in inflammation and neuroinflammation (inflammation of the nervous tissue)
  • improved brain health and a decrease in cognitive decline
  • reduced risk of cancers
  • improved blood glucose control and increased insulin sensitivity

It appears that some of the benefits of TRE come from it resetting our biological clocks. Even the evenly split fast:eat ratio of 12:12 can be very beneficial for all of us, and it is relatively easy to achieve. It means that whatever time you finish dinner, you don’t have breakfast until 12 hours later. You don’t need to skip any meals, and this period of fasting shows the body a distinct sleep:wake cycle, which helps reset the circadian rhythm which is key to our health. It also resets other clocks in our body and helps energy metabolism. Greater effects seem to be apparent the earlier in the evening that the fast begins. This means that if you stop eating at 7 pm, it is better than stopping eating at 9 pm for your 12+ hour fast. 

Time restricted eating and breast cancer

A study [1] on 3,061 non-diabetic women looked at TRE association with breast cancer. Outcomes of the study looked at blood glucose control and breast cancer events (recurrence and primary occurrence). The data analysis took into account BMI (body mass index), sleep duration, breast cancer characteristics, and dietary variables. 

On average, the women fasted 12.5 hours per night. Increased fasting duration was associated with improved blood glucose control. 

Women who fasted less than 13 hours, had a 50% higher risk of a breast cancer event compared to women who fasted at least 13 hours per night. For women who had already had breast cancer, fasting for 13 hours or more led to a 40% reduction in risk of breast cancer recurrence. The results suggest that increasing the length of nighttime fasting could be a simple strategy to improve glucose controls and reduce breast cancer risk. Further studies are needed to confirm these findings. 

Here is a video from one of the researchers for the study. There is a lot of interesting information in this video – it’s worth taking a look. 

TRE and blood glucose control

As we have seen in previous posts, we can all benefit from better blood glucose control, because of the links between many chronic diseases and poor control and insulin resistance.

The studies show that restricting your eating to 11 hours a day can have a significant effect. Restricting eating to just 8 hours a day might have great effects on weight loss and body fat levels too – and TRE is easier to comply with than other diets. TRE might be one of the simplest ways to improve your blood sugar control.

TRE is not for everyone

While 12-hour and 13-hour overnight fasts are generally beneficial for us, prolonging that fast even more, is not good for everyone.

If you are trying to get pregnant or are pregnant or breastfeeding, TRE should be avoided.

If you are particularly stressed and have “adrenal fatigue,” aren’t sleeping well, etc., often TRE is not beneficial, and you might benefit from more regular eating schedules. 

TRE as a great lifestyle choice

As we have seen, TRE can have many benefits, from weight loss, improved cardiovascular health, to cancer risk reduction. Compared to other diets and interventions, it is relatively simple to implement – especially if you initially focus on just making sure you have 12 hours fast and 12 hours eating time each day. Then, maybe you can try extending that fasting time to 13 hours or more. 

The animal data show that this approach is not something that you need to do every day. So why not give it a try when it fits into your lifestyle. We don’t want this to affect your socialization – that is an important part of lifestyle too. But on the mornings when you are rushed, don’t listen to that “old” message in your head that says you can’t skip breakfast. Maybe instead you can listen to the “new” message saying that this is a good day to try TRE. 

This style of eating is very similar to that of our ancestors. We’ve gone from eating when we were lucky enough to have/find food, to eating whenever we feel like it. Many people lose their circadian rhythm because of working late and eating late. TRE brings us back in rhythm. 

TRE also puts the body under just a little bit of stress. This is called hormesis – where a little bit of stress has beneficial effects. It gives the body some resilience for coping during times of extreme stress, thus improving our health and longevity.

My experience

I have been doing TRE for over a year now. I always have at least 12-13 hours fast. That just seems like an easy routine and is now my norm. Then sometimes I do the 16:8 fast, either for a few days a week, or for a couple of weeks. Right now I’m in a do-it-every-day-mode for a couple of weeks, and it makes me feel great. I don’t feel hungry. But I really enjoy my food during those 8 hours.

Some practitioners say you can drink coffee or other drinks when you get up (ie still in the fasting period) – but if you look at the research – and listen to the video above, you’ll see that they are quite strict on avoiding anything except water during the fast.  I stick to just water and now enjoy my coffee-free mornings.  But if that last leap puts you off – try it with your coffee and see how it works for you. 

Another bonus from this approach comes from exercising just before you break your fast. So I exercise in the morning before eating. 

I’d love to hear from you and whether you have tried it. Or give it a go and let me know how you get on. If you are monitoring your blood sugar levels – see how it affects those too. 

If you are interesting in trying TRE, there is a research study that you could join to monitor your results and help us all find out more. Take a look here http://www.mycircadianclock.org/.  It’s an app for your phone that you use to take photos of what you eat and it records the time you eat too. Then you log your exercise/activity and sleep. You will be helping more than yourself if you sign up. 

If you are interested in reading more posts like this, please sign-up on the sidebar of this page. If you don’t get a confirmation email, please let me know at ruth@calmerme.com.

[1] Abstract P3-09-01: Intermittent fasting in breast cancer risk and survivorship: Insight from the women’s healthy eating and living study
CR Marinac, SH Neslon, L Natarajan, DD Sears, CI Breen, JP Pierce, RE Patterson

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