Scientists Find No Benefit to Time-Restricted Eating | Hacker News Reader

Scientists Find No Benefit to Time-Restricted Eating

nytimes.com

63 pointsmooreds65 comments

At the very least timed-restricted eating has helped my relationship with food. When I was eating three evenly-spaced meals a day, I was constantly in this pseudo state of kind of hungry, kind of full, but never really very hungry or very full, and always thinking about eating but not eating too much. After doing a pretty easy variation of time restricted eating I literally never think about food other than when I'm eating. I really like the feeling of actual hunger, and then eating when I'm actually hungry. And how much I eat or want to eat just kind of never seems to be a problem.

But beyond that I'm skeptical of the claim there's no benefit, I've felt healthier and my bloodwork has improved, but maybe something else caused that (I wouldn't know what).

I'd imagine any plan that forced you to think about what and when you eat would make you feel better and have your bloodwork improve. If you meal prepped all food you ate on the original schedule every Sunday, that probably would also have helped. Anything that got you out of grazing on snacks all day and making eating decisions with your non-lizard brain.

Same here, it’s also helped with overall calories because the time I eat is restricted. No breakfast, eat a good lunch, eat a good dinner. All eating done within 7-8 hours, I am used to no morning calories so I don’t feel hungry until lunch, and I don’t get the 350-500 calories breakfast brings.

I can heartily second that it's helped my relationship with food.

For years I've recognized that I had an undesirable relationship with food. I really enjoy eating, both for the pleasure, and for the social interactions that come around meals. But, I felt like I was almost always "hungry" or feeling too full from over eating. I had really strong cravings for things like sour candy and ice cream, especially when relaxing at night. I'm 40 years old, 5' 8", and was pushing 230lbs. My belt which used to have four holes, and then a fifth that I made, no longer fit. I was definitely trending in the wrong direction.

The concern for me was not that I had gained a bit of weight but that my relationship with food looked more like an addiction than something I was actually enjoying and benefiting from. I was driven by my cravings and could tell I had some type of eat/crash/eat/crash cycle going on, but I felt somewhat powerless to do anything about it. The cravings were really strong.

I had tried intermittent fasting (one day 500 calories, 2nd day eat normal) a couple years ago and that worked pretty well initially. But over time, the 500 calorie day was just too hard and I'd eat way too much on the "normal" day to compensate for it. Again, a mental/physical cycle that was not healthy.

A month or two ago I came across a comment here on HN where someone shared that they did intermittent fasting by having a six hour window of eating and a 18 hour window of fasting. I decided to give it a try. Their eat window was 2pm - 8pm, but after some experimentation I've found that a 4pm - 10pm window works better for me.

I knew the window between when I woke up and 4pm would be the hardest, so I did some research and it looks like[1] a coffee or two with heavy whipping cream doesn't have an adverse affect on fat burning or glucose levels. Since that's what I was drinking anyway and like it, a coffee soon after I get up and another at 1:00 if needed gets me through the day without hunger being distracting.

I've been pleasantly surprised by how well this has worked and I think I've broken the eat/crash cycle that I had going. The most noticeable difference is that the hunger sensation is different. The sensation of actually being hungry b/c I've not eaten recently is very different from the "I just want to eat" hungry. It's tolerable and, if I can say it this way, even somewhat enjoyable in an "I have control over this now" way. When the hunger does get distracting, which usually doesn't happen until after noon, I know that I can eat in a few hours and I also know I can wait that long and it will be ok.

During my eating window, I eat whatever I want to. But, interestingly, I've found that my desire to eat is also changed. I get full faster and when I'm planning to eat I try to avoid overeating b/c I don't like how it makes me feel and I don't like going to bed stuffed. I still have ice cream and candy at night sometimes and sometimes I don't. If it's in my window, it's ok.

My weight is now trending in a different direction and I'm glad about that. But I'm not approaching this as a diet. I'm approaching it with the perspective that I need to hack my body's normal operating mechanisms to fix a unhealthy trend of compulsive behavior. That also has made a difference.

1. https://drbeckyfitness.com/coffee-and-intermittent-fasting/

Yep, this is the way I've always seen it too. You need to avoid the eat/crash/eat/crash cycle. For me the best fit is to eat breakfast, then don't eat anything until dinner. For others it's skipping a day. For others it's only eating in a 6 hour window.

It really does look like an addiction and it is helpful to frame it that way. The key element in all of these is that you need to force your body off of blood-sugar, and the only way to do so is to be off of it for a long enough time that half-life diminishes to nothing. This needs to be normal and your body needs to be used to this.

What was your routine?

> rigorous one-year study in which people followed a low-calorie diet between the hours of 8 a.m. and 4 p.m. or consumed the same number of calories anytime during the day has failed to find an effect.

Duh? The reasonable mechanism of action for IF is that it's a tool to consume less calories.

If the study's IF group is eating the same number of calories as the control group as part of the study design, this is the expected result.

> “These results indicate that caloric intake restriction explained most of the beneficial effects seen with the time-restricted eating regimen,” Dr. Weiss and his colleagues concluded.

Yeah! That is the whole point.

> when subjected to a properly designed and conducted study — scientific investigation — [IF] is not any more helpful than simply reducing daily calorie intake for weight loss and health factors.

Yeah! People struggle to "simply reduce daily caloric intake," though.

This study was merely a step in validating and adding credibility to "yeah, calories in-calories out is still the most important factor in determining weight and other health markers." The complexity of the human body shouldn't be turn into something trivial, as your comment suggests. There's a lot of people that studied/studies how the complex web of neurons impact health and well-being, and they added value to the literature. Let's not trivialize the exploration and appreciation into how complex the human body is.

While I always suspected this result to be true, there are many extraordinary claims about the importance of fasting with scientistic explanations (I've seen claims that it works because of different insulin levels, ketosis, blood sugar effects etc.).

So, this study at least puts some of these ideas to rest (if it can be replicated of course, which is not necessarily a given in nutrition "science").

> Duh? The reasonable mechanism of action for IF is that it's a tool to consume less calories.

That's not the only reasonable mechanism.

Even with the same calorie intake, there are other suggested mechanisms. For example altering glucose metabolism, shift from lipid synthesis to the using of of fat and other effects related to breaking body weight homeostasis.

Also there are some theories that spiking mTor less frequently is better. Some interesting research being doing on sirtuins and their role in repair of systems as well, especially in a fasted state.

Disappointing that there's not a word written about which group found their diet easier to stick to. The same calorie intake leading to the same results is a completely unsurprising outcome. What's much more relevant is what makes it easiest for people to stick to such an intake.

It would have been interesting though if the result was positive though. Being able to eat, say, 1400 instead of 1200 for the same effects if you change your meal time would probably drastically change people’s overall eating habits over time.

Anecdotally, I used 16/8 intermittent fasting to lose twenty pounds last year, and then stalled. At that point I started counting calories in addition to 16/8, and lost an additional twenty pounds.

Any successful diet works because it makes you eat fewer calories. What makes IF, low-carb, low-fat, or anything else work for an individual is ease of compliance. I feel better when I eat a lot of protein and skip breakfast, so I'm more likely to stick with it than other eating patterns. My wife, on the other hand, feels like garbage when she tries IF.

There is no magic bullet. Everyone's body and lifestyle is unique, and everyone needs to experiment to see what eating strategies work for them. IF is a very useful tool for many people. Eating six small meals per day is a very useful tool for others. It shouldn't be treated as a holy war.

Calories are what matter for losing weight, but losing weight is not the only reason to go on a diet.

Original study:

https://www.nejm.org/doi/full/10.1056/NEJMoa2114833

139 patients over 12 months.

“These results indicate that caloric intake restriction explained most of the beneficial effects seen with the time-restricted eating regimen,” Dr. Weiss and his colleagues concluded.

I personally do time restricted feeding and notice health benefits so I'm a bit skeptical of this study as there are a ton of variables to consider.

I think original studies done in mice that showed metabolic improvement were based on a time window that if translated to human time would be closer to 4-5 day fasts.

There can be other benefits to time restricted feeding as well for long term health and I use it to help set my circadian rhythm.

Anyway I have a lot of random thoughts on this issue but wouldn't take this study to mean time restricted feeding "does nothing". Curious about other people's experiences / thoughts.

If time-restricted eating only works because it limits how much you eat, it still works.

That's really it.

The point is that people 'graze' to maintain blood sucrose levels and avoid the problems associated with high carb diets. Were your energy levels 'dive' between meals. Because of this Americans tend to have 8-10 "meals" (ie: including snacks) a day.

If this is normal for you:

A hour or two after lunch you get distracted and tired at work so you go up to the vending machine or office kitchen and get a snack. Grab a soda, get some chips, etc to keep yourself awake and focused.

Then that is the problem here we are trying to solve.

So by having time-constrained eating habits this eliminates this for most of the day except for the time period we have designated for eating.

Which means that time controlled eating is a behavior/metabolic "hack" to reduce overall calorie consumption. This way you get conditioned to only wanting to 'graze' during a specific time period.

If you force the study participants to control for calorie input then you are accomplishing the same thing we attempt to do with time constrained eating, just in a different way.

> I personally do time restricted feeding and notice health benefits

but the study is only for weight loss not general 'health benefits' yea?

Yes, not only that, but the patients were obese. I think 16:8 schedules can work well to help maintain a healthy metabolism, but if they're obese already, they'd need to completely reset their baseline (ie longer duration fasts) to achieve the results.

This headline is misleading: no benefit. I'd have to say this is flat out incorrect.

Other comments mention bringing you back into your circadian rhythm: yes. I always sleep better when I do not eat late. Having the last meal around 5pm (don't eat after 6) is my personal imaginary cut off point. If I'm with others, I'll probably eat later, but alone I'll stick to it.

The other day I had a big lunch at 2pm and didn't eat after that. I survived. Was I hungry when I went to sleep? Yes. Did my hunger go away reasonably quickly? Yes. Did I sleep well? Yes. Was I starving in the morning? No.

Let your body feel hunger every once in a while. Especially if you live in an industrialized area where food is available at any hour and you have the disposable income to afford it.

Even the abstract directly contradicts the conclusion:

> The mean weight loss from baseline at 12 months was −8.0 kg (95% confidence interval [CI], −9.6 to −6.4) in the time-restriction group and −6.3 kg (95% CI, −7.8 to −4.7) in the daily-calorie-restriction group.

So in other words, beyond caloric restriction, the time-limited group lost more weight.

The study seems to have ignored other measures, such as inflammation markers.

Further, a 16/8 restriction is barely a restriction at all. It's trivial to consume 3 meals in that window. It's also too wide a window to measure the results of autophagy, one of the key reasons to do intermittent fasting.

The confidence intervals overlap by quite a bit. The difference is not statistically significant. If this were a clinical drug trial, the drug would not get approved.

>The study seems to have ignored other measures, such as inflammation markers.

They also ran a panel of metabolic markers, which the abstract says were in line with the overall weight loss results.

This seems to be a (very typical) misuse of NHST. All we want to know in this case is which of the following statements is the more probable:

(1) Intermittent fasting has benefits.

(2) Intermittent fasting does not have benefits.

Instead, what we're being told is that we can't reject (2) with a high degree of confidence. When you look at the sizes of the groups in the study, this is pretty obviously going to be the case. With so few participants there'd have to be an enormous difference between groups in order to be sure that (2) is false. They need hardly have bothered doing the study at all.

Well, the trick is that the confidence intervals overlap, and do so pretty heavily. So, while on average they may have lost more, their test group size was either quite small or had high variability such that it could come down to randomness that one group lost more than the other.

At the end of the study they had 61 in calorie restricted and 57 in intermittent fasting. So, not huge groups. And looking at their confidence range knowing their numbers, it likely means on both sides multiple people lost 7kg on both sides.

I didn't see a way to download that study to get the raw data, which would also be helpful, as I think it would also be useful to look at % body fat loss, etc.

Don't overlook that IF for some individuals can come with psychological aspects, such as the feeling that they're taking action, that this is something they are doing. This helps start the ball rolling toward a goal as opposed to doing the usual thing but not changing any of one's usual routine.

This is very true. Placebo effect is extremely powerful.

It's all about the calories. If you reduce them, you'll lose weight. If you increase them, you'll gain weight. Simple to say but difficult to do because we think we have to eat when we feel hungry. We don't because we have fat reserves but our body wants to save those for famines, which we don't experience.

The best way I've found to eat less is to combine keto and intermittent fasting. Reducing carbs reduces sugar spikes and crashes. A sugar crash makes you feel hungry. If you eat protein and healthy fats instead of carbs, you reduce your sugar spikes and crashes, thus reducing your feeling hungry. If I eat a meal of protein and fats, but no carbs, I can go 8 hours without feeling hungry.

This alone didn't help me lose weight because it wasn't forcing my body to use up the fat reserves on my body. Intermittent fasting can do that. I would eat two meals each day at 2pm and 8pm. I ate at 8pm because I knew I wouldn't get hungry before going to bed and I wouldn't feel hungry while sleeping. When I got up, I didn't eat. My stomach remained asleep so to speak. By 2pm I had gone 18 hours without eating. After the first 12 hours, my body started using up my fat reserves. At 2pm I had been burning fat for 6 hours.

If I didn't reduce my carbs, I wouldn't be able to fast intermittently because I'd be too hungry.

I remember when I was in ROTC I had to do training one summer. It wasn't particularly difficult, though as a part of training there's a lot of artificial stress placed on you. One source of artificial stress was timed meals. You had 5 minutes to eat your entire meal while sitting at attention. Since most of your day is spent marching around, this meant you were extra hungry at meal times. I found myself optimizing for calories per second. The first day at training I had eggs and toast for breakfast, but the dry toast took up a long time to chew and swallow. Subsequent days I followed the example of my peers and got a big bowl of grits (which I usually never eat) for breakfast which I could wolf down without chewing. By the end of training I had grown to love grits. So, long story short, one benefit I found for timed eating was a newfound love of a food I previously never tried.

I tried going mostly carb free AND limiting my eating to a 4 hour window each day. Note that this is not the same as the 8 hour window in the article. For me it worked fantastically well. Down 10 lbs in 2 weeks. Like many such efforts, sticking to it is the hard part.

IMHO most diets can work. The one that works for you is the one you can stick to.

Wait a minutes the title is all wrong compare to the scientific article. It’s not that there is no benefit, but that there is no weight loss differences. The scientists didn’t research about health in general and the impact of this type of diet, but about weight loss differences between the two diets…

I’d imagine there are quite a few studies that say the opposite? Is this study special? Larger sample size?

Other studies don't control for the amount being eaten. Time-restricted eating is a technique for eating less food, but aside from that it doesn't have intrinsic benefits.

What benefits were they measuring in this study?

I’d be curious to look at biological age markers, inflammation, autophagy, maybe improvements in insulin response, cardiovascular health in the long term.

From the original paper:

"Results of analyses of waist circumferences, BMI, body fat, body lean mass, blood pressure, and metabolic risk factors were consistent with the results of the primary outcome. In addition, there were no substantial differences between the groups in the numbers of adverse events."

So weight loss was the primary target, with some ancillary metrics. But it was only a 12-month baseline, which may not show longer-term benefits. And it didn't include any effort to assess things like inflammation or immune system robustness, which personally are the only reasons I do intermittent fasting.

Looking at a review[0] on TRE from 2020 it says:

>The studies to date in humans are limited in size and duration, and the effectiveness and acceptability of TRE in the general population remains unclear.

Skimming this new paper and it seems to me that the sample size is about twice as big as previous studies.

[0] https://www.sciencedirect.com/science/article/pii/S258900422...

Well yeah, it's like filling up your car's tank once vs stopping every 30min to add 1L. If the only thing you measure is the distance you drive you'll get roughly the same numbers. Now if you start to measure other metrics like convenience ease of maintaining your routine, energy level over the day, &c. you might conclude something else.

You can also lose weight on a pure palm oil diet, or gain weight eating nothing but tomatoes. Weight gain is only one part of the equation. There are so many variables, even purely psychological ones, the best thing is to try it out for yourself.

Intermittent fasting can help manage hunger and eating habits, but it won't magically burn more calories. People in this study were eating the same amount of calories just with different schedules. Why would that lead to any discernable difference in weight loss? The point of fasting (to me) is that you don't eat the same amount of calories because of the fasting schedule, and the focus you're putting on meal times and what you eat and, at least for some, fewer fluctuations in hunger levels throughout the day.

I would be very careful accepting the results of this study on face value.

For people interested in the Science of TRE you need to listen/read Dr. Satchin Panda's work;

1. https://www.salk.edu/scientist/satchidananda-panda/

2. https://www.youtube.com/results?search_query=satchin+panda

3. Book: The Circadian Code by Dr. Satchin Panda

>a rigorous one-year study in which people followed a low-calorie diet between the hours of 8 a.m. and 4 p.m.

8 hour eating window. Way too long if you're trying to lose weight.

That struck me as well. I’m used to seeing intervals like 11 am to 6 pm, which tactically cuts out “breakfast” and likely reduces the average calories you manage to fit in over the day.

They were managing this by having a strict diet as well. In the study both groups were on calorie counting, just one also had a time window as well.

They did lose weight, though...

Little difference in weight loss != no benefit. Your A1C is likely to drop, and that's a huge benefit for pre diabetics with metabolic syndrome. Your cholesterol is also likely to drop, which can help reduce the risk of heart disease. Heart disease and type II diabetes are two diseases greatly affecting a large number of people and intermittent fasting appears to reduce their impact. That's a benefit in my book!

How many times are life scientists going to rediscover the first law of thermodynamics before we can stop having this conversation?

The one thing I have realized two things over a period of time. One, we just don’t know human metabolism enough and we don’t have a standard way to extrapolate how a diet might impact the body. Two, all of these plans try to cheat and so may be ineffective, the only way is to burn more calories than you take in, cannot go wrong.

> the only way is to burn more calories than you take in, cannot go wrong.

Sure, but you don't control how many calories you take in any more than you control how many calories you burn. That is, your brain's decisions to try to make you over-eat are no more under your control than your intestine's decisions to more or less thoroughly digest food.

This is the part that's always over-looked by those who believe CICO is the last word on dieting.

> your brain's decisions to try to make you over-eat are no more under your control than your intestine's decisions to more or less thoroughly digest food

They literally are though. You can decide to eat less and then… eat less. CICO is the last word on dieting; but the words, sentences, and paragraphs that get you there are up for interpretation.

This only makes sense if you believe in a transcendent soul which controls the body but is unaffected by it. Otherwise, you must accept that your body influences your decisions.

Alcoholic brains desperately try to make them drink, but there are many alcoholics that continue to choose to not drink.

If an alcoholic can choose to not drink, I can choose to not eat all the Nutella.

Unless you’re diagnosed with pica, chances are that you can indeed control your urge to chow down.

BTW, is it good to keep yourself hungry for some periods of time during the day?

Now as I'm starting feeling hungry I'm not going to eat for quite some hours because I guess this is going to be good for health and weight loss. But a colleague of mine says hunger will drop my metabolic rate and I should avoid it by eating regularly.

Your body isn't really hungry, as in it doesn't need food, it's just conditioned to expect food at regular intervals. https://en.wikipedia.org/wiki/Ghrelin

We've never eaten so much food at such intervals, don't worry, you're body is fine, being hungry is not being starved.

The three meals a day + snack is a pure social construct and is a relatively recent one too, and seeing how 70+% of people in the west are overweight I'd say it clearly isn't optimal

> But a colleague of mine says hunger will drop my metabolic rate and I should avoid it by eating regularly.

That's bullshit though. Humans never lived with abundance of food around them until very recently. Your body is made to help you sustain hunger for hours and hours.

Sure, but there's no real way of knowing whether that is "healthy" or "unhealthy" or neutral for you.

That is, is it perhaps promoting some state in your body that helps with longevity and long life? Or is it eating up precious resources and making you less healthy overall? Or is it totally irrelevant to your general health levels ?

Any of these could be true while still being in line with the evolutionary claim. And, of course, ALL of them may be true for different people with different body mass, other health issues, age.

For example, your body has evolved such that you can walk or run even with a broken toe. Still, that doesn't mean it's a good idea to run after breaking a toe (if you can at all help it).

> is it perhaps promoting some state in your body that helps with longevity and long life?

Even if there is some achievable optimum, I seriously doubt it's a simple formula that can be applied to millions or billions of human beings. Complex systems are by nature complex, and we should be wary of very simple solutions and their potential to have strong effects.

Also, it's probably impossible to properly design such kind of study that would take in account a large amount of factors, removing co-founding variables and strong enough to achieve a reasonable conclusion over long periods of time.

This video does a really good job analyzing this situation with the IF 16:8 strategy. It's quite interesting that this study is backing up his thoughts on it too.

https://www.youtube.com/watch?v=zC9_g01disc

"a rigorous one-year study in which people followed a low-calorie diet between the hours of 8 a.m. and 4 p.m."

Isn't the whole idea behind time restricted diet that you don't limit calories, but shorten the time window in which you eat them?

Yes, but the whole idea of the study was to see if IF had weight-loss benefits on top of that, which it does not. This seems to prove that the mechanism by which IF works is calorie restriction, and not some other voodoo.

But, ... What a good time we have?

Non Paywall: https://www.irishtimes.com/life-and-style/health-family/time...

Paywall

I can't believe how sick I am of hearing some "scientist" finding a result against what many people _know_ works.

If "science" can prove anything then what is the solution here? Does everything have to be a battle?

I guess we should just accept that spinach is immensely rich in iron, that prayers work, and you can jinx the outcome of pro sport with comments said in front of the telly. When has the crowd ever been wrong.

Like most science reporting, the headline is a bit over-the-top, but the article is pretty straightforward. You need to consider here the control/counter-factual -- [time fasting + restricted calories] vs [restricted calories]. And both groups lost on average a decent amount of weight, it was just about the same weight on average.

Personally I do fasting as a mechanism to restrict calories (I would definitely snack more at night). It is ok if it doesn't have other metabolism benefits.

I will say I think the certainty in the interviewed scientists is a wee bit strong for my taste. There is obviously quite a bit of potential treatment heterogeneity in the population (i.e. some things work for some people and not for for others, behavioral interventions are hard).

This looks like a high quality small N for a decent followup, but you can't really look variance in treatment effects for only a few hundred observations. So definitely does not invalidate any personal experimentation someone has done and shown to be effective for themselves.

They aren't saying IF doesn't work, they're saying IF doesn't work better than other strategies, for the population as a whole.

IF works very well for some people, and there's no reason for them to stop using it. Other people feel like garbage when they IF, and end up binging; they should not use IF.

Nobody's trying to take IF away from you, they're just pointing out that it isn't a magic bullet for everyone.

The headline is garbage though, as is tradition.

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