Intermittent Fasting vs. Time Restricted Feeding

I just finished a 5-day water fast – using the two Pique fasting teas for help – and after discovering Peter Attia, and his dietary philosophy, I am now thinking what I’ve been calling my daily “Intermittent Fasting” routine is really, “Time Restricted Feeding.”

Here’s the link for Dr. Attia’s video that made me consider these definitions:

I’m on a Vegan 18/6 diet that I do every day from 6am to Noon, and Huel plays a large role in that diet.

I have always called that plan, “Intermittent Fasting” – but it does seem to make more sense that what I’m actually doing is, “Time Restricted Feeding” and not really Intermittent Fasting.

I do plan to do days-long fasts in the future – true Intermittent Fasting – and I think it may be important to make a distinction, with a difference, between the two ideals, for both the sake of sanity, and clarity.

I’m curious to know your take on this, and how you plan to label, moving forward, your current restricted eating plan, and any future water/tea fasts you may decide to implement.

I thank you!

i do 16:8 everyday (like for the past 3 months)

i do 24 hr fasts once every 2 weeks

and i even did a 48 hr fast once (which was REALLY hard)

But 5 days…

5 days is crazyyyyyyyyyyyyyyyyyyyyyy

how u do dis?!?!


Thanks for the detail, I appreciate it!

I’ve done 3-day fasts in the past without trouble.

This was our first 5-day fast – and we did everything we usually do, work, play, workout, etc. – and the first three days were perfectly fine, on days 4 and 5 we did start to feel a little hungry, but our energy was still good.

The Pique tea helped. We drank a lot of mineral water, too: Topo Chico and Gerolsteiner. Grit also played a big role. We were determined to succeed.

Peter Attia does 7-day fasts four times a year. That’s pretty incredible, and a goal. My wife did 5-days okay. She doesn’t think she’ll ever be able to go 7 days.

@boles - Great video. Very interesting. At least I know I am now out of the SAD diet. I’m still on the fence as to what I will call what I am doing moving forward. I am doing 17:7 every day and haven’t started doing several day fasts yet. So, I think I could still fall into the category of IF with the formula being: f (100, 17, 1) = (100% reduction, 17 hours - duration, 1 day - every day). If I start doing IF of several days, then I will probably start calling my daily 17:7 TRF.

One thing I haven’t done yet is to change my eating window to 8 AM - 3 PM. I have read the benefits of eating earlier in the day and then starting your fast and what happens to your body while sleeping. The benefits of ketosis while sleeping is raised with that eating window. I just don’t know if it will fit into my lifestyle. It will if my wife gets on board. If not, I will probably stay where I am at as it’s working. I was overweight and needed a change. Since April 1, I am down 32.8 lbs with about 28 lbs to go.

Thanks again for the link to that video!

1 Like

Thanks for sharing the specificity of your day! Congrats on your weight loss! If there’s one thing we know, extra weight absolutely has no benefit to the body; and there’s only one reason for gaining weight if we are actively trying to losing weight: Eating the wrong things.

My wife and I – and yes, I agree with you that if the wife isn’t on board, none of this works, SMILE! – plan to do more frequent 3-day fasts, so our daily “TRF” from 6am to Noon will become our daily diet driver.

One immediate benefit I noticed with my 5-day fast was a 50% reduction in eye floaters. That was a welcome surprise. The fact that I also lost 7 pounds was a side delight that I must now work to keep off without letting the weight snake back on my body!

I agree eating earlier in the day is better than eating into the evening – even on TRF or IF. Peter Attia and Matt Walker don’t want any alcohol or food at least 4 hours before the start of an 8-hour sleep.

Another thing that rakes Peter is the new-old-Advertising-sage that “breakfast is the most important meal of the day.” He compares two studies tracking hunger, feeding and health, with the first feeding being twice as large as the next two. All groups awoke at 5am and went to bed at 9pm.

One group ate at 8am, 10am and Noon, while the second group ate at Noon, 2pm and 4pm – and there was little to no difference between the bloodwork/physiology between the two groups that would suggest eating a big breakfast was important to overall health.


I’ll weigh in later on the IF verses time restricted feeding (nice pun, hey?).

But I wanted to comment on this “breakfast is the most important meal of the day”. I have personally found that waiting till 11 am to break my fast (which is basically skipping breakfast) was a key to my own weight loss.

But there may be a few reasons this advice has come about. I think there are some studies in kids that show their school performance is hindered if they skip breakfast. But they are growing so that may play a key role. Some people who skip breakfast are then more likely to eat more unhealthy snacks late morning or eat an unhealthy lunch.

But yeah, I agree that the specific time of day is not as crucial as just setting aside a good amount of time to be in the fasted state. Whether someone does IF or time restricted eating, they are both better than multiple meals/snacks around the clock which almost never allows insulin levels to fall to basal levels. Middle aged adults do not need to be eating 6 evenly spaced meals a day.


Here’s the Attia breakfast rant – he explains it better than I did:

(That’s one of many of his takes on breakfast and feeding…)

I have bad eye floaters and I’ve been on a Huel Diet for 18 months. I add multiple natural anti-oxidants to my regime and have just started a Candida cleanse.

Can you go over your 5-day fast? Do you eat at all during this time or is it a full fast? Did the floaters come back after your fast?

I’m willing to try anything at this stage.


The five day fast was a true fast. Lots of water. No food. Pique Tea has a few special “fasting teas” that we used to stave off the hunger, and they worked well.

That fast got rid of 50% of my floaters – floaters that I had previously increased by adding a jump rope routine to my workout – and the results have lasted.

I don’t jump rope as much now, and some floaters are still there, and always will be. I’ve just learned to “look past” them as the simplest remedy, much in the same way I “listen past” the tinnitus in my left ear.

My ophthalmologist is sort of surprised I don’t complain more about my floaters, because they’re there a lot, and they move around like bunches of tiny spiders all day, but I know there isn’t much to be done about them, so why spend time complaining?

The same doctor says it’s also sort of rare, in her experience, that I can tolerate monovision with my contacts – I guess not many of her patients are able to make that work.

When I saw his video, I started to think the same thing. (As noted in a previous post above) But, I have been doing IF for 10+ months now and have yet to do a Fast over 24 hours and after looking at Peter’s formula, my IF falls into his IF formula.

His formula is this: f = fasting (x= % reduction,y= Duration, z= Frequency)
My IF is daily and is as such: f ( 100%, 18 - 20 hours, Daily) and when the time comes that I throw in an extended fast that formula just tweaks for that extended fast f ( 100%, 24 - 72 hours, Daily).

Unless I have something wrong here, I am calling what I do all the time Intermittent Fasting. And [UPDATE - as of this morning, I am now down 59 lbs. with about 5-9 lbs to go to my goal weight, depending on where I want to land.

Lastly, I have been listening to many books on extended fasts and the benefits of them. From everything I have heard, extended fasts are very beneficial but they recommend never going over 14 days. I think I will try a 48 - 72 hr soon to see how it goes.

1 Like

Congrats on the weight loss! That’s a long and fruitful journey for you!

I’m big on fasting. My wife and I sometimes just do a 24 hour fast for a day or two and it does tend to re-energize us.

Sometimes I think the body just needs a little break from the chewing and the swallowing and the processing and the pooping. You sort of feel your body exhale in the silence a bit while you’re fasting.

If you’re both confused we lay out the differences here!


Great article! Love the research and the footnotes! Thank you!

1 Like

I do 18:6 Intermittent fasting 5 days a week, and a 16:8 2 days a week. Have been for the past 8 months. Best way to burn fat and build muscle at the same time.