Research showing weight loss leads to slower metabolism

Welcome to The Fast Diet The official Fast forums Body Benefits and side effects
Research showing weight loss leads to slower metabolism

This topic contains 18 replies, has 9 voices, and was last updated by  nanniel 6 years, 3 months ago.

Viewing 19 posts - 1 through 19 (of 19 total)

  • Hi all,

    Has anyone found after losing weight with 5:2 fasting that their metabolism is significantly lower than before? The New York Times just wrote a story where many scientists have confirmed that people who lose weight will have slower metabolisms than before:

    I do not want to lose weight from 5:2 only to find that my metabolism is slower than before and won’t be able to keep the weight off unless trying harder than I would have had to before doing 5:2.

    This article talks specifically about 5:2, and a researcher warns that 5:2 fast may slow your metabolism (4th paragraph from the bottom):

    Please share your experiences if you have found your metabolism is slower.

    Take the test in BMI calculator, put your data and weight 300lb note the BMR, let’s that you lost weight 100lb and now with 200lb, see the BMR decreased.
    A person’s metabolism decreases as it weighs less. spends up more energy to move a heavy body,.
    As we have to correct thinning calculate the BMI calculator.

    Anaide, yes, BMR decreases as weight decreases. What the article points out is that the Biggest Losers have BMR significantly lower that the average person at the same weight. And that is why they regain the weight. Not bad habits, not sloth, not anything that people can’t point fingers at. Through no fault of their own, they regain the weight because their metabolisms have slowed to a trickle, so to speak.

    The lowering of metabolism and consequent eventual weight regain happens if you follow a calorie restricted diet only, not a fasting regime.
    Read today’s article on this very misleading NYT article in Dr Jason Fung’s Blog
    … The Biggest Loser Diet – Explained) PVE

    Hi All
    I have read the article above a few times and all the comments. It seems to be saying the 5:2 diet, if used for a long time, will slow down our metabolisms permanently unless our fasts are just water. The article is also claiming that a diet that causes keotosis will improve a slowed metabolic rate.
    I don’t mind trying some water only fast days if my BMR seems to be slowing but I don’t like diets that cause keotosis; I enjoy eating a wide variety of healthy foods including carbs.
    It is certainly food for thought:)

    I don’t know, but I just seem to find it harder to lose weight in ketosis. I don’t know why, I guess I over consume fat. I have been experimenting because many say low carb+fasting is a winner combo. But when I try it, my weight stops coming off and I go into maintenance. If I have to start counting calories while low carb, I will shoot myself. I am going to try going back to my old diet with fasting to see if I can start losing again. I am hoping that I am not jacking up my metabolism. But I guess even if I am, it can’t be worse than the prediabetes and hypertension I was facing. If I have to eat less forever …oh well.


    You say youre in ketosis, what makes you say that? Have you measured it? Lots of cheap blood glucose meters that also measure ketone bodies on the market. Just try ebay and buy one. That way you can be 100% sure you are in ketosis. I water fast one day per week and at the end of 36 hours Im well and truly into ketosis. Even a small amount of sugar/simple carbs will bounce you out of ketosis. I eat virtually no added sugars in foods and most of my carbs come from veggies but I am not in ketosis until I have water fasted, that’s why Im querying that youre truly in ketosis.

    Im assuming you don’t do 5:2 or 6:1 anymore? Protein and fat also contain calories. If you eat too much protein and fats you intake too many calories. Its that simple.

    bigbooty: When I do go into ketosis, I measure with the urine sticks. Yes, even a small amount of carbs bounces me out. That being said, fasting, it takes me more than 20+ hours to go back into ketosis depending on my activity level. But, even after I am in ketosis, I have trouble shedding weight. I think that I am overconsumeing protein. I have currently been playing with my fast days, experimenting. With my current diet, I cannot lose weight with 5:2. I have tried and only lose weight the first 2 weeks of 2 months)
    My best bet is 4:3 (in my experience) as I seem to find it hard to lose weight because of the sedentary lifestyle. Only thing is that I am finding it really hard to decide on how long my fasts should be. I find it easier not to eat the 500 calories on my fast days. So I am opting for 3 24-hour fasts a week. I am reluctant to waste my next week experimenting with this, but I have to do it. If that doesn’t work I am going to kick in ADF. I don’t have a choice. I have experimented off and on with IF and in the past any fasts that averaged 20 hours did little for me. I may have to go the 36. The other option is to take count of calorie’s daily, which I am worried will discourage me as it always has in the past. I am willing to put in the work for a longer fast if it means I don’t have to count calories. I don’t go crazy at meals and have pretty much been the same weight give or take 5 lbs for the last 6 years. But I am over 15 stone and that to me is atrocious and I need to get my butt in gear. Psychologically it has taken me a long time to get to this point and I am very ready. I am at peace with my hunger and know that I can make it through my fast days. I am going to be using the Fasting Secret app to help me log and keep track.

    Hi Pink:

    I’m not sure from your comments what you are doing. You say 5:2 does not work for you, but later you say ‘I may have to go the 36’. 5:2 requires 36 (roughly). If you are not doing that, but instead doing something like 2pm to 2pm, you are not doing 5:2, you are on an every day reduced calorie diet. Your results will depend on how much you are eating each day. As you have suggested, neither entering ketosis nor fasting automatically result in weight loss. And being sedentary does not slow down weight loss because exercise contributes little to the effort.

    I guess I was confused then. You are right, I was doing something like 2pm-2pm 2 times a week. So I was doing 2 24-hr fasts a week. I now understand where my shortfall was…can’t believe I didn’t see it last year when I was first trying the diet. A definite “aha” moment. 5:2 is 36 hours! Here I was always thinking 24 and I was reaping extra benefit by not taking in the 500 calories…*slaps forehead*

    Yep its 36 hours. So for me Im on 6:1. Last meal is 7pm on Sunday night then I eat breakfast on Tuesday morning at 7am. I do a water fast. By Monday night I am into ketosis. I measure my keto with a meter.

    Try a 36 hour water fast. Its not as hard as you would think it to be. Not sure why the weight is not coming off. Having said that I did plateau on two occasions. At 84kg for a few weeks and then at 78kg for a few weeks before getting down to 72kg.

    Well I can see why the weight is not coming off, because I am an idiot, lol. Okay, new plan. I can see why, because I was still eating every day and on my fast days I was not restricting calories. My vision of the 5:2 was wrong. I was more than likely slightly over my TDEE on the other days which balanced out the “fasts”. But I did try a 22:2 eating window for more than a week and didn’t see a budge. I found it too hard to stick to and I am sure if I could I would eventually see weight loss. I am thinking I will do 4:3 with 500 calories or less. Although I know I can go the 36 hours it is hard since I cook all my family meals. I will try it for a few weeks and see if I see the weight moving down again. I was moving down with the 16:8 window but it was so slow that I wanted to amp it up. I will keep my non-fast days in check and see how the fast days work out. I will most likely keep the fast day food to one meal a day at night so that I may eat with the whole family.

    I go 36 hours with a water fast, I find it easy. I can appreciate everyone is different though. I actually found it harder when I was eating 600 cal on my fast days. I actually do a lot of cooking for the family as my wife is a shift worker. It doesn’t bother me to cook on my fast days. My routine is that I do 6:1 (maintenance mode for me now) every Monday regardless of whether Im on holidays, its a birthday etc. Im so used to it that I don’t even wake up hungry on Mondays, no longer get headaches and by Monday evening 24 hours later I am well and truly into ketosis (measured with a keto meter).

    Good luck with it now that your doing t correctly.

    Hi LH8540,

    Going back to your original question. If you do 5:2 then there will be no to minimal slow down of your metabolism. If you restrict your daily caloric intake then yes I fully agree that metabolism will slow down. So better to restrict your calories on two fast days by say 2 x 1500 = 3000 compared to 7 x 428 = 3000. Restricting every day as you would do for say a weight watchers diet doesn’t work. Under such a situation your body will slow down its metabolism.

    Hi big:

    Could you please give clinical references for your statement of fact that if you follow a weight watchers diet your metabolism will slow down (other than the natural slow down that comes from weight loss)?

    Surely you can’t point to effects after a diet where people are semi starved and forced to do up to 8 hours or more of exercise a day for 30 weeks? You must have some other clinical studies to support your claim.

    Ive been reading Jason Fung’s Obesity Code where he says this. Im hoping since he is a medical professional and this is his specialty area that he would have proof that this was the case. His assessment of what happens tends to fit well with what has happened with me. I don’t think my metabolism has slowed at all. My wife on the other hand is unable/unwilling to do 5:2. She tries to limit her caloric intake 7 days a week much like weight watchers. She is always complaining that she is cold. According to Fung this is a key indicator that your body’s metabolism has slowed down to compensate for your reduced caloric intake. I suffer no such symptoms. In fact if anything I tend to run slightly hot.

    Hi big:

    If you look around this site you will constantly find newbies commenting that they feel cold on their diet days. It is so common I addressed it in my Newbies thread. Feeling cold is a well-known and common side effect of fasting. So feeling cold from not eating is not limited to every day reduced calorie diets, and not prevented by being on an intermittent fasting diet.

    Current research estimates that about 10% of a body’s energy expenditure is used for digestion of foods. Energy expenditure causes heat output (think of feeling hot when exercising). When you eat less, the energy normally used to digest the food is not expended and heat associated with that expenditure is not released. Some, but not all, people feel cold as a result (I am one that always feels cold on diet days – even after over three years of doing IF – but I am never cold on non-diet days).

    So I guess I would agree that if the body does not have as much food to process as it usually does then its ‘metabolism’ is slower and some people feel cold. That can happen with both every day reduced calorie diets and intermittent fasting diets, although it is my observation that it happens more often with IF than with every day reduced calorie diets.

    So what is the point? Do we have to keep eating often or at high levels to keep our metabolisms rolling and stay warm? So much for our IF diet days!

    I have no doubt that is the case for a lot of people. Not sure what you can do about it other than to wear more clothes and be mindful that you need to allow for it when calculating TDEE which would be an estimate rather than an accurate number. I know that when I first started my water fasts I used to think it was my imagination that I was running hot. Perhaps there is a distinct difference between reduced calories and a true fast as to the way the body reacts. Or maybe different people react differently and there is a natural variation?

    Actually, in order to prevent the metabolism from slowing down all that’s needed is to do body cleansing from time to time. There’s Dr.Parell and other products that cleanse your body gently, and it makes it easier to follow a diet since you feel satisfied with a smaller amount of food, and it also accelerates your metabolism.

Viewing 19 posts - 1 through 19 (of 19 total)

You must be logged in to reply.