16/8 7 days a week vs 5/2

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  • Does anyone know which method is more effective for weight loss

    They both have the potential to achieve weight loss but with 16:8 you are ‘calorie counting’ while you are doing 16:8, with 5:2 you only really have to stick to your 500 calories 2 days a week. Ostensibly you can eat what you like the other 5 days but of course if you exceed your TDEE (calculator in the “How” tab on this page), you will gain weight instead. With both WOEs you will lose weight if you stay below your TDEE (but not your BMR which is what you need to eat anyway to maintain your body),

    If the 16:8 diet a just calorie counting, what is the point of restricting food to the 8-hour window? Just curious.

    16:8 is not calorie counting, although it may result in reduced calorie intake as it is harder to eat as much in 8 hours as you would in 12.

    The important bit is not the 8 hours when you eat, but the 16 hours when you do not. Depending on what your last meal was, and how much you ate, 16 hours is long enough to use up the energy from food and start burning fat. Longer fasting windows without food reduce insulin and studies show for example that eating 2 meals in a restricted period may be sufficient to reverse/ ward off diabetes (when compared to grazing all day).

    I lost weight on 5:2 combined with 16:8 and am now maintaining my weight by practising 16:8 most days of the week. I am not naturally hungry early in the morning so it suits me to break my fast at maybe 11am.

    I suspect if you want to lose weight using 16:8 alone then you would need to calorie count to ensure you achieve a calorie deficit. However, if you want to maintain but still get the benefits of a fast then you may not need to calorie count. I certainly don’t, but then I didn’t when on 5:2….

    Thanks for posting this I have wondered about the two diets. I’m doing the 5:2 mainly but find myself skipping breakfast now and again (usually as I’m not hungry). Sounds like a bit of both could be beneficial. Especially as I’m not really calorie counting.

    My next aim is to fast on a Monday then tues morning before breakfast do some form of exercise then begin eating again later on in the day. Hoping to see some results when I begin that.

    I’ve tried the 16:8 without calorie counting & didn’t lose any weight. I have however had good results on the 5:2 without calorie counting on my non-fast days (I stay within the 500 cal limit of my fast days) – I prefer the 5:2 lifestyle because of this flexibility it can offer!

    It sounds like it is important to fast for up to 16 hours, so will give that a try.

    How many days of 16:8 do you have to do in a week to get the health benefits? I don’t need to lose weight but would like to improve my health.

    Hi LouLou:

    I am not aware of any clinical studies that show following 16:8 provides any health benefits to healthy individuals. The book that started the 16:8 craze states: “In The 8-Hour Diet, bestselling authors David Zinczenko and Peter Moore present a paradigm-shifting plan that allows readers to eat anything they want, as much as they wantโ€”and still strip away 20, 40, 60 pounds, or more.” I always am skeptical of diets that say you can eat as much of anything you want and still lose a lot of weight.

    It is mostly used by people to try to reduce their eating, and if (when) it does not work, they often reduce the length of the ‘eating window’. I have seen everything from 17:7 to 23:1.

    It won’t hurt you to eat all of your calories for the day in an 8 hour period, so if you want to and think it will be beneficial, enjoy! The book even says you will lose weight doing it.

    I follow 16:8 on non fast days. I can’t eat first thing in the morning, and I find two meals a day suits me well.

    I exercise first thing most mornings on an empty stomach, and I haven’t encountered any problems doing so, even the morning after a fast day.

    As Happy Now says, the longer the fasting window the better.
    I also agree that it is hard to eat as many calories following 16:8 than if you start eating in the morning, so it can be beneficial in weight control.

    I’m really not wanting to lose any weight, but I was under the impression that 16:8 gave you the same benefits as 5:2 – like the possibility of reduced chances of developing diabetes, cancer and dementia? Is this not the case?

    LouLou22, it’s my understanding that 16:8 gives you the same benefits – it’s all down to the length of the fast. The benefits kick in after 12 hours so any fast period over and above 12 hours is a bonus. We all must remember, however, that research on the benefits of fasting is limited (and I’ve read tons on the subject – most of which is health professionals’ personal experiences, not hard scientific evidence from trials). I wouldn’t imagine that grazing throughout the day is at all helpful – it takes the body out of its fasted state (consumption of any more than 50kcals at any one time) and should almost certainly be avoided for the initial 12 hour period of the fast otherwise the suggested health benefits of fasting will be lost and it becomes nothing more than calorie restriction which will aid weight loss but maybe won’t benefit the body in the way complete fasting does.

    LouLou, Might I suggest that you read the book. The fast diet is about the health benefits of fasting which comes with a bonus of weight loss. There is plenty of information for those who want health benefits without weight loss.

    Thanks all, I’ve been googling and my head is mashed from all the conflicting information haha! I will have a read at the book, thanks Amazon ๐Ÿ™‚

    i did a kick off of a one day water fast, which nearly killed me haha

    then i have done a few days of 16:8 because my husband hasn’t been out shopping for my 5:2 days, but i reckon i will try them both together as i kind of like stopping eating at the end of the day and having my brain perk up.

    because of my sleep patterns, i prefer to fast at the end of the day.

    i am sure hoping that this works for me… on the water fast day i lost nothing, but have noticed that i have moved a couple of lbs on the 16:8 days… probably because i eat less during my eating window…

    thanks for the topic

    I have been on the 16:8 diet fot just over a week, and find it easier to do than. The 5:2, i have loss a1lb so far, so am happy with that, I start to eat from 1pm till 9pm and drink water the rest of the time, i found it hard to get in 3 meals so am on two with a couple f healthy snacks, i do this 7 days a week, and wonder if this helps or as i have read is it better to do it five days, I. Prefer 7 days as I get so much more done in the mornings, my question is should i lose a good weight loss and health benefits on this and do also check my calories to stay within my limit, I usually burn about between 2000 – 4000 cals a day, with dog walking and gardening, I like. To have an odd cake, but I bake my own as I hate to have to much sugar, just wondered if anyone else has been on the 16;8 longer than the just over a week I have, thank you

    As previously stated, 16:8 is not a diet it is a restricted eating window. If you are restricting calories you will lose weight.
    Are you sure you can burn up 4000 calories a day? You would have to do several hours of strenuous exercise every day to do that, and gardening and dog walking don’t fit the bill. I am asking because the amount of exercise and its effect on weight loss are generally over estimated and because it takes me more than an hour of cardio at the gym to use around 500 calories.

    You burn about 100 calories per mile walking. So that’s about a 40 mile walk with the dog to burn 4000 calories. If what youre doing is working keep doing it. If it stops working re-evaluate.

    I personally don’t buy into the 12 hours of fasting is enough to deplete the glycogen in the liver. There is always some lipolysis occurring and while it is probably higher after 12 hours I don’t think the bigger shift starts until about 20 to 24 hours of fasting for most people. Perhaps sooner if someone has a smaller liver. In my own fasting I can feel a shift generally around 20 hours in, strangely I often notice it in how my face feels. However I’ve often checked and that is about the time my blood glucose tends to dip for a while. My last fast I didn’t workout and I didn’t feel the shift until about 23 hours into the fast. I realize this is just my feelings, but it something I’ve learn to expect. (I do zero calorie fasting.) I’m pretty sure this shift I feel is related to the dip in blood glucose that I’ve measured and that is probably related to my liver running low on glycogen.

    Anyway the 16:8 intermittent fasting was first pushed by people doing weight training. If you couple a 16 hour fast with HIIT or weight training you’ll might have something that has additional benefits beside weight loss.

    There isn’t anything wrong with weight loss, but longer fasts have additional impacts that I’ve noticed.

    * I’ve really been able to build muscles much easier. Probably have higher levels of HGH and testosterone. It seems likely I have lower insulin levels now too. (Judging by waist size)
    * I always notice I burn about 15% to 20% more calories on days after fasts, at least by my activity tracker. Sometimes I even get as high as 3200+ … but I haven’t gotten close to 4000 calories/day yet and I’ve tried. ๐Ÿ™ Too old and weak I guess. Today I’ve done 7.3km, 117 floors of stairs and 130 pushups and on pace to burn about 2750 calories for the day.
    * Much more healing, for example I had golfer’s elbow and that has healed. I had bad plantar fasciitis and that has healed.
    * While fasting I feel peppy! That kicks in more towards 20+ hours.
    * I’m sleeping better, but that took months to happen.
    * I crave real food, although that could be from greatly reducing added sugars in my diet.

    Anyway my feeling is 16:8 without hard workouts is more of just calorie restriction, hopefully without the long term metabolic adaptions that plague people depending on calorie restriction. If there are other benefits it probably takes many days to equal one longer fast. I’ve also fasted up to a week and I think it probably takes many 36 hours to get the benefits of one mult-day fast.

    Short fasts are probably great for weight but I’m pretty sure that 6 16 hour fast won’t provide the benefits of one 96 hour zero calorie fast. Maybe 60 or more 16 hour fasts would be need, I don’t know and I don’t think there has been any research on that.

    Hi. I’ve been doing the 16/8 method for six weeks now and have lost 3kg without counting calories at all and eating what I feel like, even curries and pies. As I was only 63.5kg to start with I am amazed at the success of this method. The way I do it it is last food my 3.30pm most days and then soy latte at 7.30am. I usually have a protein shake after training to which I add a heap of veges. Whatever takes my fancy for lunch and then at 3.15 I start my final meal which is usually pasta dish or curry and rice or salmon in pastry with veges or soup with toast. In fact this is the easiest diet I’ve ever tried. Never tried the 5/2 as I couldn’t cope with restricting to 500 cals.

    A lot of people do see great success with 16/8 IF. I’m glad it is working well for you @wendye50.

    I think you would find fasting for a full day much easier than you think. I find it is easiest just to not eat anything and stick to a water fast. I’ve done it now for about 200 days and I’ve only had a few times where it was kind of rough. However it seems you are doing fine with your 16/8.

    The thought of fasting a whole day every week, for me, sounds horrendous dykask and unnecessary. Eating whatever i want within an eight hour period is just so easy.

    I’m doing 5:2 but hit a plateau mentally and physically. I knew if I sorted the physical the mental would follow. Often now (after following 5:2 since new year) I am not hungry in the morning so I decided to do 16/8 a couple of days a week too. I’ve been doing it a couple of weeks and this morning weighed in, and I’ve got past the weight barrier that had eluded me since April.

    Eeyore no idea why anyone would choose 5/2 over 16/8. 16/8 is just so easy.

    I started on 5:2 then added in 16/8. I find 5:2 easy but I couldn’t manage the switch to 4:3. 16/8 on some non-fast days works for me.

    I still find 16/8 only okay on a temporary basis. One of the issues I have with it is nutrition is harder to maintain because fewer hours of eating means I lose a meal that I normally have control of. It can also be very socially restrictive. Ending my eating a 3:30pm everyday just isn’t an option with family. Skipping breakfast throws out the only mean I have complete control of nutritionally. I find that 2 days of water fasting a week is about as much as I can push the social issue.

    The other problem is that 16 hours of fasting isn’t enough to really push the body into a fasted state unless I were to go on a low-carb diet. A lot of the reasons for fasting are more health related than just weight loss. Long term there are a lot of questions about just how healthy going low carb is. Anyway I don’t normally eat large amounts of starchy carbs. Still low carb diets tend to be very restrictive and tend to push protein much more than I’m comfortable with.

    I find that I typically fall into a pattern of eating breakfast later, lighter lunch and a supper with family on my eating days. More of a 13/11 or 14/10 pattern.

    Anyway I strongly disagree that 16/8 is so easy because of the these reasons:
    * Family eating patterns
    * Nutritionally more limited
    * Reduced effectiveness compared to fasting longer

    It really boils down to what fits into one’s lifestyle. Water fasting 2 days a week is typically very easy too. It isn’t a question of which is easy. It is a question of what one can maintain.

    At the end of the day, what ever works for you is THE best solution. I hit my weight target about 3 1/2 years ago but have maintained 6:1 ever since and my fasting day is a true fast. Im sure I could just as easily not fast and maintain a constant weight but I firmly believe that fasting has many benefits that go way beyond simple weight loss. Ive now gone a fourth winter without catching a cold. Family have just had their colds (no one else fasts in my family). I believe fasting keeps your immune system in peak condition.

    Everyone has a different take on fasting. Do whatever is sustainable for you.

    Yes I agree my eight hours finishing at 3.30 wouldn’t suit everyone. My daughter, who has a family goes from 6pm to 10am. Just got to find the 16/8 that suits. If I do eat later. I just do 16 from that time. Occasionally I’ll just have a 14 hour but I still lose weight over a week. Nothing else I’ve tried works so consistently but it’s the not having to count calories, carbs or anything else is what makes it the easiest and most successful.

    Dykask I still manage my five veg a day mostly in a protein shake.

    @wendye50 – I don’t count calories because I eat a lot more than what I did when I was using calorie restriction, well except for my zero calorie fasting days. Anyway you haven’t tried 5:2 by your own admission so you can’t be sure it wouldn’t even be better. It is pretty simple, when you don’t eat you lose weight. ๐Ÿ˜€

    Personally I think 16 hour fasts are pretty limited. Even the 36 hour fasts I often do are only about 16 hours into a fasted state since it typically takes about 20 hours before I experience a good drop in blood sugar.

    There is nothing wrong with liking the 16:8 plan you are doing, but don’t knock 5:2 when you haven’t even tried it. In fact I was fasting for months before I tried 5:2 and when I did I was rather shocked at how easy and effective it was.

    Dykask. I did try it and wasn’t able to last the whole day on 500 cals. Each to their own. If I have to suffer in any way it doesn’t work for me. I’m looking at something I can do longterm. An eating plan, not a diet to lose weight then stop. This is so manageable and working for me, that even when I get to my goal, it won’t matter if I don’t stick to it ridgidly a couple of days a week. That will be my version of maintenance. But I still believe everyone needs to do what works for them. But if I can lose 500gm every week without trying, I imagine someone with a lot of weight to lose could really benefit from this method. I’m sure the 5/2 works just as well, but being hungry 2 days every week is not my idea of a long term solution.

    @wendye50 the solution is to just water fast. The hunger isn’t bad, even at first. After a few times it is very manageable. As I pointed out you haven’t tried it so you should be slamming it.

    @wendye50 the solution hunger is to just water fast. The hunger isn’t bad, even at first. After a few times it is very manageable. As I pointed out you haven’t tried it so you should be slamming it. Personally I would find it very difficult to get through a day on 500 or even 800 calories as eating stimulates hunger for me. However many people do just fine on it and they don’t complain of extreme hunger either, in fact many find it very easy.

    I have done 16:8 and many other forms of IF and I believe my points are valid. There are tradeoffs of each. Personally I don’t think 16:8 is even really fasting, it is just closer to what used to be normal. When I was a kid most people ate in a 10 to 12 hour window and snacking was rare where I lived.

    Since you don’t have anything of value to say about 5:2, why are you even posting here? It seems you are just trying to scare people away from it. The are many examples of people failing on various forms of IF too, including 16:8. Eating patterns aren’t magical solutions by themselves. Even people with bariatric surgery can force themselves to start gaining weight again and that is far more restrictive than either 5:2 or 16:8. Any eating pattern requires work to make it successful.

    For myself I’m more concerned about health and building lean body mass as I was at a point where I was losing muscle mass with normal calorie restriction. 16:8 and other forms of IF like that were a bit better, but I didn’t start noticing major changes until I started fasting through the second night. (However I never tried OMAD approach.) Maybe that is just my body type, but that is the main reason I like 5:2, well the fasting is still a brief 36 hours, it is still enough to have good impact on my hormones. I’ve tried longer fasts too, but didn’t see much gain over the 36 hour fasts except in weight loss. I’m sure there were effects I couldn’t detect and they sometimes fasting 5 or more days is quite healthy, but it is just out of my primary window.

    I think the real value with 16:8 here is for the people that are combining it with 5:2 as more of a way to limit their eating. That is likely even more important for the people that don’t do zero calorie fasting. With more than 200 zero calorie fasting days under my belt, I find I rarely have a problem now with overeating. In fact the amount I’m eating has been declining naturally. However many people struggle with overeating and 16:8 seems to be a good choice to limit that.

    Anyway, for most, hunger is rarely a show stopper with fasting.

    I realize a lot of people are sold on 16:8 and have good success with it alone. So I know it works for many people. I just found it too gentle and not as effective as the full day fasts. (2 nights and in-between day, ~36 hours) I think there are a lot of factors. A lot of people really happy with 16:8 seem pretty young and it could be it is much more effective with younger people that don’t have such a deep hole to dig out of. It is also really popular with people doing a lot of weight lifting. In that case they are already stressing themselves and the milder 16 hour fast stress may be all they need.

    That being said I think for a lot of people it just reduces how much they eat. That alone can have major benefits if someone goes from over-eating to normal eating.

    It probably does reduce how much you would normally eat. I’m not young, but it is working so I’m sticking to it as a lifestyle change rather than a diet. I can’t water fast, I need the energy and would dread that day every week, so for me, not something I could adopt for life. If it works for you that’s great. I only need to lose a few kgs so am happy with slower progress. I wish you success in your journey.

    @wendye50 you are still injecting misinformation. Short term water fasting actually increases metabolism, it doesn’t slow it down. There are studies backing that up. I don’t have an issue with you not wanting to do water fasting, I only take issue with the misinformation. While different people can have differing responses it doesn’t make a myth like short term fasting reduces a persons energy true.

    When I started water fasting over 24 hours the main side effect I experienced at first was becoming too alert, it interfered with sleeping on the second night. However I never really felt tried from it, just made the nights a bit long.


    Now around 20 to 24 hours there can be a period where the body is adjusting to running out of glycogen. In my case I used to feel a bit light headed then when my blood sugar temporary dropped some. I used to just do some squats or some other exercise and it would pass quickly. Now it just doesn’t seem to brother me at all. The timing of that could change a lot depending on a persons diet.

    Anyway, most people here do 5:2 because it is easy to do and it is also effective. For me I know first hand the 16:8 everyday was difficult mainly because of lifestyle issues, however I didn’t do it enough to know how effective it would really be. It just doesn’t work well with family life.

    Hi dykask,

    I’m just now starting on the IF path and 5-2 sounds like the best option. Would you say it’s completely non-advisable to do it on 2 consecutive days? I’m trying to find something I could stick to as a life style change, and fasting like this for 2 days in a row like Monday and Tuesday would be easier than trying to adjust social schedule to do it on non-consecutive days. Thanks!

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