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Are you fit? as in, do you lift weights or are active in sports that require strength?

I ask because I wonder about the effects of extended fasts on muscle loss/retention, a big problem cutting weight for some people is that they get rid of some muscle mass along with the calories they wanted to eliminate.

I did for a few months this year, but I've been lazy over the summer. I'm 155lb, 6'0, so fairly skinny, maybe at around ~15% BF. I noticed that fasting doesn't help with BF at all unless I eat very clean and lift. I was at 170lb, around ~28% BF earlier this year and had to work my ass off to get my body fat percentage down.

Lifting specifically, or any sort of physical activity? I’ve been running and IF for the past month in order to cut my BF %. I was at about 16%, but I’d like to get down to 12%.

Lifting; I did Stronglifts 5x5 3 times a week. Part of the reason I stopped is that it got kind of boring and I got absolutely sick of doing squats 3 times a week.

It sucked, it was hard (especially on a caloric deficit), but it worked.

I've found that lifting is much better for weight loss than running/biking. I've gained weight while running 30-40 miles/week and typically lose weight while lifting (if I pay attention to my calories.) A lot of people say the same.

If you're focused on BF%, lifting is even more appealing since you'll be building muscle/reducing bf% even at a constant weight.

> I noticed that fasting doesn't help with BF at all unless I eat very clean and lift.

So what happens? You lose muscle and fat in the same ratio? Or do you keep the fat?

I feel that my body kind of adjusts to the fasting and I just don't lose much of anything.

That sounds to me like "I eat more to make up the calories when I'm not fasting".

I haven't seen any studies that imply that fasting increases or decreases metabolic rates, which would mean that most people probably won't implicitly gain or lose significant amounts of weight just by switching to intermittent fasting.

There are people that literally just start skipping breakfast while keeping lunch/dinner/snacking the same. This is both technically intermittent fasting but also a reduction in overall caloric consumption. These people sometimes attribute their newfound weightloss to IF, when really they just started skipping a calorically dense meal every day.

Fat first cus it’s easier to break down. Muscle afterward.

That's what I would assume, but they said the opposite.

Interesting. I just started experimenting with a 16-8 fast, and I have noticed that it is hard to eat larger portions when you constrain the eating window to eight hours. Did you think it helped maintain your 15% BF?

> Did you think it helped maintain your 15% BF?

Nope.

I stopped counting macros and started eating just whatever again at the beginning of the summer and I'm slowly gaining the fat back. Unfortunately, there are no shortcuts (at least for me).

I'm personally very skeptical [as well]. I notice that almost nobody that recounts their fasting experience ever mentions sport.

I personally found very hard already to progress on weightlifting during diet cycles, as I need to cut on volume significantly; can't imagine to do that while fasting, unless fasting would "flip a switch" in how the (my) body works, which I doubt.

"I'm personally very skeptical [as well]. I notice that almost nobody that recounts their fasting experience ever mentions sport."

Allow me to step right up.

First, as you might expect, aerobic and endurance exercise benefits greatly from being in a fasted (16-24 hr) state. You're light, quick and your body is devoting zero blood flow (and other resources) to digestion. I suspect you're not surprised by this.

Second, I do a 1.5 hour heavy leg workout which includes squats, deadlifts and other assorted "big" movements with weight that is significant, compared to my body weight. No issues at all. I wouldn't do this on a 24 hour fast, but it is my regular habit to do this workout while in a 16-18 hour fasted state and in general I have very slightly better results than if I had eaten recently. Again, the issue is the amount of blood flow (and other resources) your body is putting into digestion.

Finally, while it is easy and enjoyable to do my BJJ workouts in a fasted state, I cannot, then, do several rounds of sparring at the end without more recent calories. Or rather, I can but I after round one or two I am running out of gas.

YMMV. You should just try it. It costs nothing.

First, as you might expect, aerobic and endurance exercise benefits greatly from being in a fasted (16-24 hr) state

If that's true, why isn't it a universal practice in amateur and professional athletic competition?

(Or, for that matter, why isn't it banned?)

I can't speak to endurance (I got into IF after my endurance-athlete days) but I know that body weight-based athletes do this to perform better. My experience is specific to rock climbing.

When you are right at the edge of your abilities being just a couple pounds lighter can feel like a world of difference (people hone down their rack to precisely what they need for a route, nothing more), especially on sport and boulder problems. My anecdata points to it being great for the project/performative aspects of the sport but as a tool for consistent progression/improvement, I am less confident in stating anything.

> First, as you might expect, aerobic and endurance exercise benefits greatly from being in a fasted (16-24 hr) state. You're light, quick and your body is devoting zero blood flow (and other resources) to digestion.

I'd say it depends greatly on the effort and the individual. Long, slow distance for someone who is accustomed to training fasted? Fat stores will suffice as an energy source.

But add in some intensity and that's gonna be rough without much glycogen in the tank - which will be the case if you've been fasting for the past 16-24 hours.

I've experimented with fasting and weightlifting and I want to share some thoughts.

First, fasting does not require that your overall calorie intake is reduced. If your cut-goal is 2000kcal per day, you can fast in the morning and eat all 2000kcal in the afternoon. Ultimately, I find this is actually an easier and less hunger-inducing way to each your cutting goals.

Second, you're right. Doing weightlifting while fasted is hard. It's better to coordinate your gym schedule with your eating schedule so that you can eat -- I like a simple protein shake -- before and after the gym.

Third, I'm seeing a lot of folks talking about intermittent fasting ("IF") and day-long fasting in the same breath. I think IF is great for weightlifters on a cut diet. But I think day-long or multi-day fasts are different and should only be done occasionally (weekly being the most frequent) if you are trying to progress with weightlifting. YMMV.

There is some evidence that appears to support the idea that there is a difference between calorie restriction and complete fasting. You sound like the type of person that likes to dig into the studies. Dr. Jason Fung does a good job of writing in plain English while linked to and referring to the supporting studies: https://www.dietdoctor.com/fasting-muscle-mass

The studies may not have been conducted among athletes so, testing your own body's response (by measuring lean body mass before and after a fast) seems like the best way forward.

I have read that people on keto diets or fasting have less "explosive" energy for workouts. I am not concerned that my body is going to cannibalise my biceps if I don't eat for a day or two. There is a lot more energy kicking around that is less important.

For me, it's worth it for the HGH boost: https://www.dietdoctor.com/fasting-and-growth-hormone

There is a recent US Military study that shows that under a severe caloric deficit and with increased energy expenditure that yes, you still preserve lean body mass. [0] Granted this was not fasting, but it's interesting nonetheless.

Don't be thrown off by the title. Yes, one group received testosterone, but even the placebo group that did not receive anabolic steroids, lost nearly 10 pounds of fat without losing any appreciable amount of lean body mass.

Dr. Peter Attia wrote about it in his newsletter this past week. [1]

Between my anecdotal experience of not feeling like I lose much lean body mass while fasting, this study above, and recent evidence from studies shown that "muscle memory", where a muscle can quickly regain any lost size it has had, is in fact real...I don't lose much sleep over losing muscle while fasting.

[0] https://www.sciencedirect.com/science/article/pii/S235239641... [1] https://peterattiamd.com/can-you-preserve-lean-body-mass-dur...

I can speak to this a bit. I practiced intermittent fasting (eating once per day) for nearly a decade, while maintaining a very low activity level. My resting metabolic rate dropped significantly during this time (down to about 1300 kcal/day).

About a year ago, I increased my activity level significantly (distance running, hiking, strength training, cycling) and quickly found that:

a) I wasn't recovering quickly enough

b) It was extremely difficult to take in enough calories for a day in a single meal

c) I had very low energy when in ketosis

Eventually I gave up and just started eating on a typical 3-4 meal a day schedule. My RMR steadily increased back to baseline, I got a lot more explosive energy, my body began responding much more rapidly to training, and my recovery speed improved significantly.

Personally I think that intermittent fasting is not a good idea if you are very physically active. That's just my opinion from my own experience.

There is a range of IF between one meal per day, and not doing it at all. Prof Sachin Panda’s research on mice shows effects of 12hrs/12hrs, 8hrs eat/16hrs fast, and fasting some days but not every day.

Did you experiment with any other patterns?

I think for that you might want to research Protein sparing modified fasting, https://en.m.wikipedia.org/wiki/Protein-sparing_modified_fas...

Gist of it is you still cut significant calories only eating like 500-800 a day in mostly low fat protien rich foods. Targeting only enough protien to avoid muscle wasting.

While I'm no doctor or nutritionist, my understanding is that it's for that case, you want some of the benefits of fasting like going into ketosis while maintaining lean mass.

Unfortunately I'm on my phone only this week so I can't try and find any studies about it, but I came across it first in connection with type 2 Diabetes. So you might have some luck googling those topics for more info.

In the book Obesity Code, it says that during fasting human growth hormone levels increase. This maintains muscle mass.

Around my 30s I was quite overweight ~310lbs/140kg. Had done some stronglifts 5x5 and then decide to incorporate Keto into the mix (later targeted keto + IF). In the course of few years went down to ~230lbs/105kg while my lifts all went up (e.q squats from around 375lbs/170kg --> 460/210kg). At least my personal "gut feeling" is that I gained some muscle mass (my priority was to drop weight/fat).

For the past year, as an experiment, I've eaten carbs "normally" while doing 4x week gym. Few things I've noticed. My gut doesn't feel as good as it did while keto/IF, when you are in Keto and eat a cup of oatmeal ~45min before gym and start lifting you have this insane focus for the heavy 1-3 reps, I can seem to tolerate more better quality volume now compared to while doing keto/IF. But the overall feeling I have outside of the gym while not being in Keto/IF is a bit "sad", so most likely I'll start doing Keto/IF again to feel better. It's funny how insanely sweet strawberries taste while in Keto, and I kinda miss that feeling.

Can you point to any studies that show the benefits of your vitamin regimen? You point out there are no studies on long term fasting but I am also unable to find the studies on the benefits of vitamins.

This is a fair point. In fact, most research seems to point to the fact that vitamins don't really do anything. I just do it out of habit.

Most nutritional studies are worthless.

Studies of taking vitamins aren’t nutritional studies in the sense of “diet”. They’re more similar to studies of drugs and can be reliable.

examine.com is a pretty good resource on supplements.

https://www.health.harvard.edu/staying-healthy/should-you-be...

https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessiona...

https://www.ncbi.nlm.nih.gov/m/pubmed/23930726/

https://www.ncbi.nlm.nih.gov/m/pubmed/27713952/

When it comes to vitamins, the typical, North American diet is likely deficient based on the following behaviors.

  I am inside all day and get no sun - Vitamin D
  I do not eat wild caught fish - Omega 3s
  I am vegan - B12
  I do not eat greens daily - Multivitamin + Magnesium Theronate/Glycinate

Most people are D & Omega 3 deficient. Also a bulk of folks are Magnesium deficient unless they are eating greens daily.

- Even on fast days, make sure you take vitamins (I take Fish Oil, Zinc, a Multivitamin and Magnesium)

I have done some fasting recently (water, some water/apple cider vinegar in the morning; coffee, green tea, Ooolong tea), and have a similar vitamin intake (B complex; calcium/D combo; Magnesium; Zinc; Iron; Fish Oil).

During the fasting I don't take the Fish Oil, I haven't read anything about it specifically, but just assumed Fish Oil was fat that would break the fast. Do you have an opinion on that? I'm Guessing the caloric intake (if any, I am not even sure) is not enough to trigger metabolic response, and as a fat wouldn't trigger insulin response.

In a talk my parents sent me a few years ago, the speaker (I believe a nurse) argued that you need at least ~20 calories to trigger a metabolic response. Hence, things like tea, coffee (even with a tiny bit of milk), fish oil, etc. should be fine.

A tablespoon of cod liver oil has 122 calories.

In general with a good diet there is no need to continuously take vitamin supplements.

In my case I am an endurance athlete, so at minimum supplementing electrolytes is helpful (also during the fast electrolyte supplements have at least seemed beneficial to my experience). Also, most American's are low on Vitamin D, and trust me I prefer it from the sun myself, but currently Im an office worker, so I supplement that.

Anecdotally, I can tell you that historically I used to get sick 2-3 times a year minimum, and since I began taking vitamins 5 years ago I got sick 1 time.

But I do generally agree with you about vitamins and minerals coming from diet over supplements, but I also say if you can get all your vitamins and minerals from food, your just not running enough (thats a joke).

I have to take Vitamin D all year. I got really sick a year and a half ago due to low levels and wound up with some other issues that it triggered. Turns out, I have MS and the low vitamin D probably helped trigger a flare.

I literally cannot get enough Vitamin D in the winter: The days are short here in Norway and the sun isn't enough. Theoretically, I might be able to get it in the summer, but I really need to wear strong sunscreen since a medicine increases my skin cancer risk. The neurologist doesn't really want me to not take the supplements anyway.

My diet isn't bad. Mostly vegetarian, though I try to eat fish once a week and not otherwise completely devoid of animal products (dairy, for example). The rest of my bloodwork turns out OK.

That also assumes you're getting enough sunlight. A lot of people who work in an office don't.

That's a bad diet compounded by a bad lifestyle. Working in an office does not mean one has to stay indoor all the time and at weekends.

If you live far enough North it basically does mean that for a good part of the year. Going to the office, it's dark, and it's already dark again when leaving. Need that supplement.

- During the fasting I don't take the Fish Oil, I haven't read anything about it specifically, but just assumed Fish Oil was fat that would break the fast. Do you have an opinion on that?

A fish oil pill has around 14 calories and most of the times will break your fast -> Take it after your first meal.

Vitamin D is a fat soluble vitamin and you should take it only after a meal containing some fat. Taking it while fasting will just not be absorbed.

> I also do intermittent fasting basically daily (I only eat between 12-8).

I settled on this pattern years ago before I heard anything about it. It just seems right and natural for my body. I've never been into snacking and breakfast would make me feel ill most days (coffee gets a pass) so that naturally means I don't eat before lunch.

Though I wonder how much of that is our modern lifestyle. If I go to the gym early or do something physical, then I'll get hungry and actually want food. Usually I try to go to the gym around 10am or later, which I do without any food in my system and I feel fine. I'm not trying to gain mass though.

I’m pretty much the same. It’s been great for me. I’m 5’11” and in two years I’ve gone from 200lbs to 155lbs with almost no effort. I feel and look great, and with low body fat I have much more motivation to exercise as well. I find it easy to ignore hunger so it’s effortless.

> Egg whites and chicken + broccoli

As an aside, a meal consisting of just this isn't very balanced. There is effectively 0 fats in it. Egg yolks are actually quite healthy and would have rounded this meal off nicely

My daily intake was 175g protein, 150g carbs, and 50g fats. To hit those macros reliably, egg whites for breakfast and chicken (or tuna) for dinner will quickly become a status quo :)

That's an insane macro ratio for most people, though. You don't need that much protein unless you're doing some intense weight training.

Not sure I'd call it insane. 5c:3.5p:1.5f is like the "standard" fat-loss macro ratio your average nutritionist would suggest[1]. Mine was a bit more aggressive, but not super out there.

[1] https://www.womenshealthmag.com/uk/food/healthy-eating/a7053...

High protein ratios are for for weight loss; activities that increase protein need increase carb need by at least as much

Why would your body breakdown your organs when you still have plenty of adipose stores ?

Do you have a citation for the "starvation mode" ? If it's the 1940's study from MN, that was only when the subjects where well into single digit fat %.

You can see that there was protein turnover just after 10 days in rats: https://www.ncbi.nlm.nih.gov/pubmed/7119891

In healthier rats, protein turnover (cannibalizing muscles / organs) was faster than in obese rats. I had some human studies bookmarked, I'll try to find them again. There were a few ketosis studies that discussed "starvation mode" so maybe try searching for that.

> I had some human studies bookmarked, I'll try to find them again.

Please do. Rat studies are helpful, but not definitive-- close but not exact. That's why it takes so long for medicines and therapies that are shown to absolutely work on rats still take forever to reach humans.

>Why would your body breakdown your organs when you still have plenty of adipose stores ?

Most people are not "fat adapted" meaning their body/brain primarily run off of glucose.

When you fast and your body runs off of glucose, it still goes into ketosis and burns fat, but the brain still needs glucose because that its accustomed primary fuel source (think of marathon runners hitting the wall, that is their body conserving remaining glucose in the body for the brain to function). When their is no dietary glucose the body breaks down protein (muscle and organs) to convert into glucose to keep the brain working (gluconeogenesis).

This will still occur but to a far lesser degree to people who are fat adapted and primarily use fat for energy.

This phenomenon (specifically, body breaking down muscles), is a very practical, and doesn't really need studies.

When doing bodybuilding (or sports in general), one can very easily measure their own bodyfat, and losing more muscle than fat is the enemy #1 during diet cycles (whose objective in fact is to minimize muscle loss and maximize fat loss).

Of course, "plenty of adipose stores" is relative. I guess that if one is 30% BF and never does any activity, as soon as they start to lift some weights, they'll put muscles and lose fat quickly for some time, independently of the calories deficit.

The other exception is when one takes anabolic steroids.

Bodies aren't finite state machines and the concept of "modes" can be misleading. What you have is a (very large) number of independent processes that have differing amounts of flow under different conditions.

So, for example, you don't click from building muscle to consuming muscle. What happens is that catabolism has a higher flow than anabolism, so the net balance is negative.

As the body becomes leaner in starvation conditions, processes that recover energy from gluconeogenesis or from lipolysis cannot produce "enough" energy. So feedback loops that suppress the breakdown of organ tissue weaken and eventually that loop shifts.

Clarifying some of what I wrote above --

* "independent processes" is better described as "interdependent, oftentimes antagonistic processes".

* In describing net balance, the key is that both processes remain active throughout, even if only the net balance of flow can be observed. Or more likely, the integration of the net flow over time (the stock).

* I say "that loop shifts", more accurately the loop dominance shifts. This is a term from system dynamics for describing how the behaviour of the overall system can suddenly change due to a change in flow of one or more loops that are working antagonistically.

"Unfortunately, eating healthy is hard and kinda' sucks. Egg whites and chicken + broccoli gets old pretty fast."

I welcome any opportunity to point to almond butter as an extremely dense, and healthy, source of calories.

Easy to add to a smoothie.

Speaking more broadly, I would have a hard time with IF, etc., were it not for shifting about 20-30% of my calorie input to nuts, generally. Mostly raw in form.

>shifting about 20-30% of my calorie input to nuts

I wouldn't do that. Nuts contain tons of metals that you don't want to overdose on.

"According to the finding of the research, any amount of Pb, Hg and Sn were not detected in the organic certified nuts. In the organic certified nuts, the levels ranged between 5.53-123.78 ppb Cd, 8.22-16.62 ppm Cu, 0.24-1.86 ppm Ni, 15.03-46.37 ppm Zn, 444.1-810.6 ppb Cr, 22.06-67.42 ppm Fe and 1.24-3.14 ppb As."[1]

Perhaps you are speaking of conventional (non organic) nuts and seeds ? I would not consider consuming those.

[1] https://www.cabdirect.org/cabdirect/abstract/20183271188

Why would organic nuts have less heavy metal toxicity than conventional?

Your link is broken btw.

Based on the quote I tracked it down to this paper: "Determination of heavy metal contents in some organic certified dried nuts". I can only access the abstract, couldn't find it on sci-hub. The study is focused on organic nuts though, it's not specifically an organic vs non-organic.

https://www.researchgate.net/publication/325951651_Determina...

Is it any better or worse than the cheaper and more available peanut butter (with no additives)?

The biggest benefit I've found to fasting is the sort of reset it provides the digestive system. I've suffered from some pretty frustrating gut health issues over the past few years, and taking a 1-3 day fast every few months significantly improves most of my symptoms. When talking to my doctor, a combination of "reduced inflammation", "digestive rest" and "gut biome health" are all things that get thrown around, but generally "Who knows, but if it works keep doing it" is the general result.

I would think minerals would not be readily absorbed without stomach acid from a meal.