Why You Need to Be Doing Time Restricted Feeding (TRF)

You may have heard of TRF but it was likely referred to as intermittent fasting (IF). It has become a popular dieting trend and for good reason: nearly everyone can benefit from not eating like a pig from sun up to sun down.

TRF/IF have been defined as restricting all the calories of food one eats to a specific window time within a day. Outside of that window, you would not consume any solid or liquid calories. Water, tea, and coffee are usually allowed. A popular regimen is the “16:8” whereby you eat all your food for the day within an 8 hour window and fast for the other 16 hours.

Scientifically and philosophically speaking, I prefer to use the term TRF for the following reasons:

  1. In research IF is usually defined as fasting for 24 hours a few days out of the week (e.g. 1-5 days)
  2. In the context of a 16:8 regimen, TRF is more true to the work you’re actually doing and IF betrays the meaning of a true fast. Many people think they have “fasted” by not eating when they go to bed for a whole 8 hours. All you’re really doing is prolonging the time between meals and since we’ve grown so accustomed to eating all day, anything outside of that is considered to be “fasting.”

To avoid being too pedantic, I am going to use TRF for the remainder of this post.

If you’re pre-diabetic or type 2 diabetic, TRF is easily one of the most simple yet powerful weapons you can wield to get back to a life without worrying how high your blood sugar is.

Here’s how it works:

  1. Choose a TRF regimen. Some popular ones are 16:8, 18:6, 14:10. The smaller number refers to the number or window of hours which you will consume your food and the higher number refers to the number of hours you’ll be fasting. If your diabetic, I recommend starting with the 18:6.
  2. Now that you know the number of hours you’re allotted to eat, choose the window of time. In this case it could be 10am to 4pm or 12pm to 6pm as an example. I prefer to skip breakfast, so I would go with the to 12-6pm.
  3. Now that you know the window…begin! Only eat food during your designated window. DO NOT consume any calories outside that window. Water, tea, and coffee without additives are allowed during your fasting window and are HIGHLY encouraged.
  4. Do this for at least 5 out of the 7 days of the week to start

If your pre-diabetic or full blown diabetic, then you can start implementing this right away and you don’t even have to change the quantity nor quality of what you’re eating (for now). You’ll still see benefits.

You might be thinking this is just a fancy mind trick to get me to eat less calories. It turns out there is more going on here which was demonstrated in nicely done study. I’ve laid out the study but feel free to skip if you just want the punchline.

Portrait of handsome confident doctor with medical gown with smart phone standing near the window in the modern dark interior clinic or office

The Study

In a small but very well-done study by Sutton et al., eight pre-diabetic men were randomized to undergo an early TRF schedule whereby they only ate during a 6-hour period early in the day (e.g. started early in AM with a time window ending no later than 3pm) and went without food for the remaining 18 hours. They did this for five weeks and then crossed over to be their own control after a seven week washout period. During the five week control period, the subjects ate during a 12 hour feeding window, 7am to 7pm. Early TRF did not significantly affect fasting glucose nor mean glucose during a 3-hr OGTT versus the control arm. Importantly, 24-hour glucose was not measured in this study. Early TRF did significantly affect measures of beta cell responsiveness, fasting and mean insulin levels during the 3-hr OGTT, and insulin resistance. Mean fasting insulin levels decreased by 3.4 mU/L, and mean and peak insulin levels decreased by 25 and 34 mU/L, respectively.

The Punchline

This study was rigorously controlled. Study participants ate a standard regimented diet provided by the investigators, they were directly observed by study investigators to ensure all food was consumed, and sufficient calories were provided to maintain the subjects’ weight. Previous studies had suggested the cardio metabolic benefits of TRF were a result of the subjects’ weight loss. The investigators demonstrated metabolic benefits of early TRF in pre-diabetic men in light of a eucaloric diet and the absence of weight loss.

In other words, what we learned from this study is that in men with pre-diabetes, TRF had benefits that were INDEPENDENT of weight loss.

I’d like to see more results in women and people with full blown type 2 diabetes. There is an ongoing trial that should show results soon. Nevertheless, plenty of anecdotes around the world suggest TRF has reversed people’s diabetes, so my question is, “why wouldn’t you try it?”

Salad – healthy fitness woman and man couple laughing eating food lunch sitting on beach after workout. Mixed race Asian Caucasian female model and male models in sportswear.

To suggest we need more evidence to try a lifestyle intervention like this is preposterous. This isn’t a pill you pop. It’s cutting back the hours you eat in a day. No one should feel guilty or like they need permission to do this (see disclaimer at the bottom of this page ).

I implement some form of TRF nearly everyday. I usually eat from 12pm-7pm. Many times I am not perfect and when there are special occasions, I give myself permission to enjoy the occasion. The median American consumes food for a 12 hour window each day. Don’t be median and you’ll reverse your high blood sugar in no time.


Leave a Comment

Your email address will not be published. Required fields are marked *