> The mean (SD) reduction in energy intake was -313 (509) kcal/d for TRE, -197 (426) kcal/d for CR, and -16 (439) kcal/d for controls
So — the time restricted eating group reduced calories more than the group that counted calories; but the resulting weight loss has the same cause: reduced calorie intake compared to before.
If there’s a take away here, it’s possibly that adherence to a calorie deficit using a time restricted eating plan is easier than adherence to the same calorie deficit by explicitly tracking calories.
If you can adhere to a calorie deficit through other means, you won’t lose weight faster by adding intermittent fasting while maintaining the same calorie intake.
I've done both. I can attest that intermittent fasting, at least for me, is WAY more sustainable ... and actually makes maintaining a calorie deficit easier too.
Hunger is a weird thing. People tend to assume that if you don't eat you'll just get hungrier and hungrier. The reality is that hunger comes in waves. If you can ride out a wave of hunger for 30 - 45 minutes it goes away. And the longer you don't eat, the less hungrier you get. I think this is because those waves of hunger tend to correspond to your eating habits. So if you're accustomed to eating lunch, you feel hungry around lunch time etc.
After a period of adaptation, when this just becomes the new normal, you can find that when it comes time to eat you just don't want to eat all that much either. It's weird, but cool, and seems to work well for a lot of people.
Then there is metabolic adaptation, which is thought to be the biggest contributor to people re-gaining any weight that they've lost. What happens is that after dropping around 10% of your body mass, your body kicks in a survival mechanism whereby it lowers your resting metabolic rate to adapt and try to slow the weight loss. This means that two people who weigh the exact same, one of which just dropped a bunch of weight to get there, will require different caloric intakes just to maintain their weight. The person who just cut weight will need 300 - 400 fewer calories per day than the person who didn't.
If you cut weight just by caloric restriction alone, this is DISASTROUS, because you are hungry and weak and miserable ... and you need to eat even less just to keep the weight off.
Which is why crash diets don't work. You start by making sacrifices, which is uncomfortable, and then when metabolic adaptation kicks in you stop seeing results unless you make even more sacrifices. People can't stick with it so they stop dieting and very quickly and easily regain the weight.
Intermittent fasting not only helps with hunger control, but there is research that suggests that it can also increase resting metabolic rate, which can help to counteract metabolic adaptation.
But even if it didn't boost RMR, the fact that it helps with hunger control and maintaining a calorie deficit alone would make it more sustainable for more people than just trying to eat less in general.
I'll add that intermittent fasting (16/8) has also conditioned my brain (and stomach likely) to eat less during the non-fasting window. In 6 months I'm down 20 pounds (198 to 178), I've also removed alcohol consumption except for in-person social events. My main concerns with 16/8 are:
1. I drink coffee in the morning, it helps with hunger, but im also wondering if this will have long-term affect to my stomach
2. I'm losing weight, but I'm wondering what to do to stop losing it, I'll soon reach a healthy level.
3. It gets annoying being told 'you shouldnt skip the most important meal of the day' by people all the time.
I've been doing IF consistently for about a decade. I never needed to lose weight, I did it to improve my healthspan. This is just my experience so obviously YMMV
1) I drink coffee in the morning too. No stomach problems yet, but I'm completely dependent on caffeine. Last summer I did a 4 month hiatus from caffeine and at the end I determined the tradeoff for me wasn't worth it. The energy and focus is just too valuable, to go without.
2) If it's going well, I wouldn't worry about it. At some point your body will stop having a huge fat reserve to burn off, and you will find that your energy levels crater and recover very slowly if you exert yourself too much for a given macro load.
3) You should try an extended fast! My response to "you are skipping the most important meal of the day" is "I don't even eat every day, fasting is good for you". If they press the issue I'll tell them about fasting for 5 days and how good it makes me feel.
And extended fasts really do make me feel amazing after the fact.
The more that one experiments with these diet changes, I think, the more one reveals how untrue that phrase "most important meal of the day" becomes. I feel unstoppable if I skip breakfast, lethargic if I don't.
I'd like to see a RCT that compared two time-restricted eating groups: 7am to 3pm, and noon to 8pm. Which would have the larger benefit over a control group?
Also, it would be good to simultaneously (somehow) check if the results depend on one's genetic or cultural bias towards eating in the morning or evening.
It most definitely is highly personal, like most weight management advice seems to be.
The only immutable truth is that calorie deficit will make you lose weight.
BUT different people find different methods of calorie deficit easier to handle mentally and/or physically.[1]
I can easily go even 20 hours without food maybe only sipping on some water or tea, my grandmother is the same. She can just have a big meal once per day and go about her day (and night) just fine.
My partner on the other hand needs to eat every 3-4 hours or they become completely unbearable mentally. It doesn't need to be a full meal, but some kind of calorie top-up is essential.
[1] ...and it seems that different people get different amounts of calories from the same food, it's a gut flora thing.
Probably depends a lot on what (and how much) you eat for breakfast too?
If I don't have some kind of protein in the AM, I quickly start having mental/emotional issues (and end up with recovery problems due to exercise, including pain). Trying to make up for it at lunch is a losing battle.
Just an anecdote, but for a few years I always skipped breakfast and had black coffee, and I did eventually develop some pretty severe heart burn issues. I went to tea for a while, back on coffee but usually eating breakfast again. I guess I’d just keep an eye on it and take action before it gets extremely painful, I’m not sure it’s guaranteed or anything.
Yeah I agree it makes it easier to eat less calories, and it's a simple rule to follow.
Sometimes I might count calories also, but if I just eat within the window it is unlikely I'll go over.
However, one unforseen side effect for me is that I sleep better on an empty stomach and feel better when I wake.
Years ago I did some experimenting on myself, including increasing to gain weight, and at least for me hunger seems to mostly be a function of relative emptiness from recent maximum fullness.
Sounds odd, but let's say I filled my stomach to 90% of my total capacity, then a few hours later I've digested down to 45% capacity and that's when I get hungry. That's -50% of the last maximum. If I spend a week or two restricting what I ate to a maximum of 60% capacity, I'd only get hungry around 30%, also -50%. But with less total calories eaten.
(numbers made up just to give an idea what it felt like)
I do 24-48 hour fasts weekly and for me the single biggest determinate of hunger is what I ate the day before.
Carbs, especially sugar and processed carbs make the fast day’s miserable. But if I stick to meat, vegetables and some whole grains it’s usually no big deal.
> If you can ride out a wave of hunger for 30 - 45 minutes it goes away.
I read "the glucose revolution" and it talked about reducing blood sugar spikes. If you have a big blood sugar spike, later you will have a blood sugar crash with a lack of energy, reduced concentration and... cravings.
I suspect that if you minimize your blood sugar spikes, you will reduce the crash later and waves of hunger aren't as much of an issue.
> If you can ride out a wave of hunger for 30 - 45 minutes it goes away.
I don't know how scientific this is but this comes from a person I consider smart & knowledgeable:
My medical doctor friend explained this as hunger being triggered by a nerve signal from your stomach that food in your stomach _is about to run out_. That is, once it runs out, the nerve signal goes away.
Before starting intermittent fasting I decided to try out a 24 hour fast, just to see how it would feel, and I felt abysmal and ravenous by the end. But after eventually starting intermittent fasting (which I ended up doing for at least 3-4 years), I had a few times where I would casually fast for nearly two days just by skipping my window one day, and it was not especially difficult.
Our bodies are so absurdly adaptive to just about anything we can throw at them. And so it makes sense, in some weird way, that if you're going to do something - doing it to an extreme degree can make things easier than going half way, since you optimize for the adaptive response from your body.
I've heard from many people who have had success with IF that somewhat more aggressive schedules (e.g. 20-4 compared to 16-8) can be easier to maintain.
I think it's just going to vary a lot by person. I tried a 12-8 fast which basically just meant skipping breakfast which seemed like a gentle intro. A few weeks in and I was so painfully hungry at times I was noticeably irritable and having trouble waking up. Also, didn't lose a single ounce.
I've not really tried fasting, at least not deliberately. I do notice that the times I get hungry differ depending on whether I'm at home or at work. Expectation of when you are going to eat does seem to factor into it somehow.
> After a period of adaptation, when this just becomes the new normal
Yep, and eventually even hunger you do feel is easy to ignore. I practice TRT and was meeting a friend at 3pm for a late lunch. I just skipped food all day, ate a nice meal at 3pm and then a very light dinner. Wasn't ever hungry after working out and working up until that point.
Agreed. My mom was complaining that she had a blood test scheduled for noon where she had to fast before the test. I was confused as to what she was upset about, and then finally realized that she didn't think she would be able to fast until noon. I'd been doing IF for so many years that this problem didn't even occur to me. Like, you can't go until noon without eating? :-)
Bingo. This is pretty much exactly what I found to be true after many years of failing to lose weight - then adding IF/TRF to the party - it made it a lot easier.
It's also psychologically easier to manage. People have an easier time building a schedule where they do or don't eat and holding it (say, by skipping breakfast) than they do managing counting calories around things like "I went out to dinner and probably ate too much".
Binary choices (should I eat right now?) take much less cognitive overhead than spectral choices (What should I eat? How much of it? If I eat X and Y now will I have the capacity to eat Z later?)
The incredible thing is you don't really need to count calories, you just have to avoid complete garbage.
As Michael Pollan says "Eat food, mostly greens, not too much".
Don't eat anything processed, don't eat anything with more than one ingredient and only eat meat with at most one meal, and ideally quite a small portion.
Completely and utterly ignore things like icecream, chocolate, soda, candy, chips, anything deep friend and other "non food items". Treat them like Arsenic - i.e. you should never eat them.
There, you are now restricting calorie intake and you didn't have to count anything.
Out of all the advice in these comments, this contradicts the scientific evidence on fitness and nutrition the most. Everyone should do the thing that makes it the easiest for them to attain their health and fitness goals. Living an an acetic life because an internet comment and Michael Pollan said so will work sustainably for very few people.
Adherence/consistency is the single most important factor to consider when building a fitness plan. Evidence shows users of systematic plans like weight watchers points are less likely to lapse in the long term. A very gradual improvement that works for a long time is much better than a deep “improvement” you practice for 1.5 months before giving up.
I’d much rather count calories and eat ice cream every day than treat ice cream as arsenic. For me a little bit of a treat every day makes self control around my diet easier overall - I never buy snacks or overeat at meals because I think “hrrng if I spend this calorie now, I cant spend it on ice cream tonight”. Might not work for everyone - there’s a lot of commenters here who prefer TRE because it’s easier for them; if works well that’s what they should do.
If living an acetic life without treats works the best for you, then do that - but don’t tell other people they should do it too.
There’s no reason to fear treats if you can manage them; if time restricted eating or calorie counting enables someone to eat the food they like, and so life is more enjoyable and it’s easier to adhere to a good diet, they should do that.
> you just have to avoid complete garbage. As Michael Pollan says
That reminds me of something I saw a long time ago:
> Fuzzy Pink Niven's Law: Never waste calories. [...] Don't eat soggy potato chips. Or cheap candy. Or an inferior hot fudge sundae. Or a cold soggy pizza.
What humans consider food has changed more in the last 100 years than it did in the preceding 10,000. Eat what your great-great grandmother would consider food, not what a scientist in a lab is trying to sell you as food.
Cake, donuts, ice cream, etc derive their extreme calorie density and negative satiety from cream, sugar, and frying, not some recent invention by a "scientist in a lab".
It's not hard in the sense that solving complicated math problems is hard, but hard in that it adds a non-trivial amount of effort to an activity you do multiple times a day, every day, in perpetuity.
Even the small effort of measuring your creamer with a teaspoon instead of just pouring it in the cup just takes more time and effort than simply checking what time it is.
This is not really true. Generally speaking, at the grossest level of averaging, regularly eating 2 meals instead of 3 or 1 meal instead of 2 results in a long term net reduction of calories.
Additionally your stomach shrinks under this regime - that one meal will definitely make you feel full and satiated.
All this goes into ease of adherence - I just don't have to think about it. I eat as much as I want for dinner each day and have dropped a steady 10lb/year for the last 5 years.
And the actual title of the study is 'Effect of Time-Restricted Eating on Weight Loss' which describes a concept that is basically the colloquial definition of intermittent fasting.
The popular term 'intermittent fasting' usually describes time restricted eating, with a fasting period usually between 16-20 hours.
Sorry, no. Whether it was always the definition or not, having a daily window to eat that is generally much shorter than normal is called intermittent fasting.
Except for those people who wake up and have a midnight snack.
Cutting out the snacking is probably also a major factor in the effectiveness of intermittent fasting, especially given that snack foods are often more processed, calorie-dense, and less nutritionally balanced than what we typically eat at meals.
I think a lot of people could lose significant weight by simply eating three meals a day at the usual times, but just cutting out snacking between meals entirely and changing nothing else. Just fasting between meals, if you will.
Good observation! Fasting in general is usually at minimum 8 hours, which is also around the time we sleep. There seems to be some evidence that the longer one fasts, the better the benefits. You would be surprised how many people in the US eat right up until they go to bed, and then eat breakfast right after waking up. So for some, extending the fast 2-5 hours is no small feat.
I see this kind of 'well actually' style response a lot when calorie counting vs intermittent fasting gets brought up. Yes they're both forms of calorie restriction in general but the mechanism and the ease of adherence is pretty difference so important to study especially given the results that IF seems to be significantly more effective because it's easier to execute.
After causally seeing popular weight loss advice in US media over the years offering all variety of silver bullets (One Weird Trick etc), I was flabbergasted and betrayed to learn how simple the math of weight loss is once I finally looked into it 4 months ago.
Very roughly, there’s 3500kcal in 1lb of body. Given that fact plus your current weight and calorie intake, you can build a spreadsheet in 30 mins to compute the calories per day to make your body any weight you want in a reasonable time frame (losing >1% a week is generally viewed as unhealthy and risky).
Of course adhering to the plan is the challenging part - and then it’s helpful to consider strategies like TRE, once you understand the metric target part.
I wrote the comment as a reaction to the editorialized headline suggesting to some degree that TRE is a silver bullet / One Weird Trick. Maybe it is effectively that for many people - but in case there’s a casual reader scrolling past I want to give them a bit more of the ground truth that’s somehow not popular knowledge.
> Very roughly, there’s 3500kcal in 1lb of body. Given that fact plus your current weight and calorie intake, you can build a spreadsheet in 30 mins to compute the calories per day to make your body any weight you want in a reasonable time frame
emphasis on the very roughly ... a significant part of body mass is tissue you do not want to lose: bone, brain, organs
1lb of fat is ~3500 calories and that is simply 9 calories per gram of fat X 453 grams in a pound. its actually closer to 4000 but people just use 3500 because that means you would need a 500 calorie deficit per day to lose a pound a week.
That doesn't strike me as "well actually". The title says "more effective than calorie restriction". If it's a form of calorie restriction, then the title doesn't make sense: "Form A of calorie restriction is more effective than calorie restriction".
I think a clearer title would be something to the effect of "Intermittent fasting more effective than calorie counting for calorie restriction"
Also worth pointing out that the study was specific to T2 diabetes.
Nothing really works that well for most people ,and there is a lot of ambiguity. I am thankfull we have GLP-1 drugs , which unlike having to compare CR vs IF, seems to work for most people .
I’ve been IF for a while now, and it’s the easiest approach to “putting down the fork.” Rather than continuing on a standard eating schedule, simply skipping a meal or going longer between eating actually creates a new habit rather than trying to modify a bad one.
I’m actually capable of going an entire day without eating now and I’m not craving anything. A lot of days I’ll only have one meal, sometimes two.
It’s done wonders for my health. I’ve lost a little under a point per week (wouldn’t recommend more than this), my blood pressure is down, I no longer get heartburn after eating anything, and I feel lighter and healthier.
There are also tons of studies indicating that going longer between meals is healthier, and had anti aging effects on a cellular level. Seems to be an all around winner to me.
if you have a 'daily budget' of 1500 calories, personally I would much rather skip breakfast and have a burger and fries for dinner than 3 'slim meals' throughout the day (i'd probably stick to that more readily too)
Adherence is all about psychology! Although what works for one person might not work for another as well; if time restricted eating or calorie counting doesn’t work for you, try a different strategy.
My target right now is 1600 kcal & 150g protein, and my usual meal plan is a 300kcal protein frappe coffee thing in the morning, a lunch around 450kcal like gumbo, a 550kcal dinner like apricot glazed salmon w/ couscous, and then ~300kcal of Ben & Jerrie’s ice cream for dessert. For me adherence is super easy because those are all foods I love to eat, I’m full all day so I never want to snack, and I’m actually eating more dessert than before this diet because I don’t feel guilty about it anymore (yay decadence).
My girlfriend tried the same plan, but something about just knowing about the budget makes her feel totally trapped and she ends up binge eating snacks almost out of “revenge” after a few days. ¯\_(ツ)_/¯
I skipped breakfast for years because I was too lazy to make it. Then I ate fast food and pizza all the time and I still got fat. You're not gonna lose weight just skipping a meal.
While dietary adherence might be easier with that eating schedule, it isn't optimal from a protein metabolism standpoint. With any calorie restricted diet you risk losing lean muscle along with fat so you need to get enough protein to mitigate that (along with certain types of exercise and other factors). And that protein should to be split across at least two separate meals in order for your digestive system to process it effectively.
I don't believe it's as simple as what's the net -ve because with TRE the BMR (Basal Metabolic Rate) does not reduce like with calorie restricted eating, so the net -ve is higher with TRE even when the calorie intake is the same. Also, reducing the BMR has other negative effects because the body does away with key repairing processes to live with the reduced availability of energy.
I think at reasonable sustainable fitness planning & weight change goals the BMR changes aren’t a significant factor. My target is to lose about 0.9% body weight per week. I did some napkin math numbers before starting my plan and decided not to worry about it much, and in my case seem to be fine.
I went from somewhere around 2400kcal daily to 1600kcal daily while eating 3 meals and lifting for 30min a day and my estimated resting energy expenditure per day by Withings & Apple Health is down about 60kcal over ~4 months. They’re not super accurate sources, but at current rates I’ll hit my target minimum weight before my estimated resting expenditure has dropped -100kcal.
Everyone's different. I did IF for 6 months and lost to the point of being gaunt, so I had to stop. It seems to have changed my metabolism for the better, because now I can eat what I want (mostly pizza and ice cream) without gaining weight. Of course, I don't overeat, or I would gain weight.
Intermittent fasting doesn't suddenly change the laws of thermodynamics. Of course if you still eat 2,500 calories a day you will likely gain weight unless you already have a lot of muscle (but if you do, you likely know what you're doing enough that you're not reading this article actually hoping to learn anything).
The point is that IF makes it easier to reduce calories, in part psychologically but also in part because it's just a lot harder to eat 3,000 calories in 4 hours than it is to eat 3,000 calories in 12 hours.
Yeah this is what people often forget. In the end it comes down to calories in vs. out. Unless IF revs up metabolism in some way, which the evidence suggests it does not. No free lunch, sorry.
The problem with your thinking is that you assume that your eating habits don't effect your energy consumption. But that is wrong, if your Blood Sugar is to high your Body can't access Fat and needs to Burn other sources that are scarce and it prefers to make you tired and cold to reduce energy consumption. That doesn't happen if your Blood Sugar is very low and you can easily access your Fat reserves. Eating spikes your Blood Glucose, that's why intermittend fasting works so great.
I've (unintentionally) done intermittent fasting for most of my adult life. Frankly, it's just mindless. I don't have to think about it that hard. When I did keto or calorie counting years prior it was basically not only part of my day but part of my life.
I looked briefly into this and it seems that while there is evidence that intermittent fasting may be useful in preventing cancer and may be useful as an adjunct cancer treatment (in addition to chemotherapy and/or other treatments), the effect is largely from weight loss, not other mechanisms. Review article here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9530862/
From the conclusion:
"There is presently little evidence that intermittent fasting, without any reduction in body weight and proper balanced diet and exercise, can enhance cancer outcomes."
So, while the details in this review are interesting, the conclusions seem to come down to basic health advice: maintain a healthy weight, eat a healthy diet, and get exercise. Seems like good advice for pretty much everyone.
The only challenge of intermittent fasting for the masses if anyone happens to need to take medication in the morning that requires some food. Moving the eating window isn't always ideal.
The problem with most diet/fitness advice is that it comes from fit+healthy people who've never had serious weight/health problems, and for whom it's all easy.
Appreciate you stepping out to engage in this. I’m going to answer this in support of the perspective you’re speaking from.
There is advice available from people who haven’t always been healthy and fit, but are now.
Should someone seeking diet/fitness advice take it from someone who hasn’t become and remained reasonably fit or diet?
One thing for me I strive towards is remembering building discipline is one of the key if not the master habit that unlocks so many other ones. For me a responsible mindset empowers, and a victim or blame mindset disempowers and I try not to forget it.
Longevity whether I like it or not is based on two things, a bit (not a lot) of regular exercise where uninterrupted walking over 60-90 minutes is amazing, and reducing the amount of processed food and step by step making sure the diet is one that best suits each individuals body. Reducing a harmful activity is a great start instead of making big leaps.
I have folks with weight and health problems in my life.
It’s easier sometimes to think it’s easy for people who have it done, but not know their story
Starting and keeping going 1% better every day is the way and something everyone can learn to do relative to themselves as long as they don’t compare, and don’t stop. Intermittent fasting (starting with a smaller window and increasing it by 5 minutes every day than normal can be very helpful).
For an example that isn't from such people, there is always The Hacker's Diet[1]. I'm not nearly type-A enough for it to work with me, but at least it's from someone who struggled with weight.
> The mean (SD) reduction in energy intake was -313 (509) kcal/d for TRE, -197 (426) kcal/d for CR, and -16 (439) kcal/d for controls
So — the time restricted eating group reduced calories more than the group that counted calories; but the resulting weight loss has the same cause: reduced calorie intake compared to before.
If there’s a take away here, it’s possibly that adherence to a calorie deficit using a time restricted eating plan is easier than adherence to the same calorie deficit by explicitly tracking calories.
If you can adhere to a calorie deficit through other means, you won’t lose weight faster by adding intermittent fasting while maintaining the same calorie intake.