24 hour fast

Sidesteal

WHEN IS IT OKAY TO JUMPSTART MY METABOLISM. ONLY AT BREKFIST?

I'm going to invent metabolic jumper cables made out of licorice ropes. I'll be rich.

mommyweighless

WHEN IS IT OKAY TO JUMPSTART MY METABOLISM. ONLY AT BREKFIST?

I'm going to invent metabolic jumper cables made out of licorice ropes. I'll be rich.

Lmao they wouldn't even have to work..you'd get rich simply because of the hype that would create the next fad. I simply do not understand this mind set around starvation mode.

tempest501

Its complete rubbish that you need to eat often to keep the fire burning. Not only that you could fast for longer than 24 hours an din fact some people do it for 36 Hours (see Lowcarbcory on youtube). You will not go into starvation mode or see a decrease in metobolic rate until 60-72 hours and people should not be fasting for this long anyway the benefits of fasting peak at 24 hours.

And here the proof that you do not need to keep the furnace burning..

1. Myth: Eat frequently to "stoke the metabolic fire".


Truth

Each time you eat, metabolic rate increases slightly for a few hours. Paradoxically, it takes energy to break down and absorb energy. This is the Thermic Effect of Food (TEF). The amount of energy expended is directly proportional to the amount of calories and nutrients consumed in the meal.

Let's assume that we are measuring TEF during 24 hours in a diet of 2700 kcal with 40% protein, 40% carbohydrate and 20% fat. We run three different trials where the only thing we change is the the meal frequency.

A) Three meals: 900 kcal per meal.

Six meals: 450 kcal per meal.

C) Nine meals: 300 kcal per meal.

What we'd find is a different pattern in regards to TEF. Example "A" would yield a larger and long lasting boost in metabolic rate that would gradually taper off until the next meal came around; TEF would show a "peak and valley"-pattern. "C" would yield a very weak but consistent boost in metabolic rate; an even pattern. "B" would be somewhere in between.

However, at the end of the 24-hour period, or as long as it would take to assimilate the nutrients, there would be no difference in TEF. The total amount of energy expended by TEF would be identical in each scenario. Meal frequency does not affect total TEF. You cannot "trick" the body in to burning more or less calories by manipulating meal frequency.

Further reading: I have covered the topic of meal frequency at great length on this site before.

The most extensive review of studies on various meal frequencies and TEF was published in 1997. It looked at many different studies that compared TEF during meal frequencies ranging from 1-17 meals and concluded:

"Studies using whole-body calorimetry and doubly-labelled water to assess total 24 h energy expenditure find no difference between nibbling and gorging".

Since then, no studies have refuted this. For a summary of the above cited study, read this research review by Lyle McDonald.

Earlier this year, a new study was published on the topic. As expected, no differences were found between a lower (3 meals) and higher meal (6 meals) frequency. Read this post for my summary of the study. This study garnered some attention in the mass media and it was nice to see the meal frequency myth being debunked in The New York Times.

Origin

Seeing how conclusive and clear research is on the topic of meal frequency, you might wonder why it is that some people, quite often RDs in fact, keep repeating the myth of "stoking the metabolic fire" by eating small meals on a frequent basis. My best guess is that they've somehow misunderstood TEF. After all, they're technically right to say you keep your metabolism humming along by eating frequently. They just missed that critical part where it was explained that TEF is proportional to the calories consumed in each meal.

Another guess is that they base the advice on some epidemiological studies that found an inverse correlation between high meal frequency and body weight in the population. What that means is that researchers may look at the dietary pattern of thousands individuals and find that those who eat more frequently tend to weigh less than those who eat less frequently. It's important to point out that these studies are uncontrolled in terms of calorie intake and are done on Average Joes (i.e. normal people who do not count calories and just eat spontaneously like most people).

There's a saying that goes "correlation does not imply causation" and this warrants further explanation since it explains many other dietary myths and fallacies. Just because there's a connection between low meal frequencies and higher body weights, doesn't mean that low meal frequencies cause weight gain. Those studies likely show that people who tend to eat less frequently have:

* Dysregulated eating patterns; the personality type that skips breakfast in favor of a donut in the car on the way to work, undereat during the day, and overeat in the evening. They tend to be less concerned with health and diet than those who eat more frequently.

* Another feasible explanation for the association between low meal frequencies and higher body weight is that meal skipping is often used as a weight loss strategy. People who are overweight are more likely to be on a diet and eat fewer meals.

The connection between lower meal frequency and higher body weight in the general population, and vice versa, is connected to behavioral patterns - not metabolism

Source: http://www.leangains.com/2010/10/top-ten-fasting-myths-debunked.html

Here is the section on starvation mode:

4. Myth: Fasting tricks the body into "starvation mode".


Truth

Efficient adaptation to famine was important for survival during rough times in our evolution. Lowering metabolic rate during starvation allowed us to live longer, increasing the possibility that we might come across something to eat. Starvation literally means starvation. It doesn't mean skipping a meal not eating for 24 hours. Or not eating for three days even. The belief that meal skipping or short-term fasting causes "starvation mode" is so completely ridiculous and absurd that it makes me want to jump out the window.

Looking at the numerous studies I've read, the earliest evidence for lowered metabolic rate in response to fasting occurred after 60 hours (-8% in resting metabolic rate). Other studies show metabolic rate is not impacted until 72-96 hours have passed (George Cahill has contributed a lot on this topic).

Seemingly paradoxical, metabolic rate is actually increased in short-term fasting. For some concrete numbers, studies have shown an increase of 3.6% - 10% after 36-48 hours (Mansell PI, et al, and Zauner C, et al). This makes sense from an evolutionary perspective. Epinephrine and norepinephrine (adrenaline/noradrenaline) sharpens the mind and makes us want to move around. Desirable traits that encouraged us to seek for food, or for the hunter to kill his prey, increasing survival. At some point, after several days of no eating, this benefit would confer no benefit to survival and probably would have done more harm than good; instead, an adaptation that favored conservation of energy turned out to be advantageous. Thus metabolic rate is increased in short-term fasting (up to 60 hours).

Again, I have choosen extreme examples to show how absurd the myth of "starvation mode" is - especially when you consider that the exact opposite is true in the context of how the term is thrown around.

Origin

I guess some genius read that fasting or starvation causes metabolic rate to drop and took that to mean that meal skipping, or not eating for a day or two, would cause starvation mode.

bhankiii

There's plenty of scientific evidence that fasting a day or two on a regular basis promotes longer life, better health and keeps your brain sharp. (please don't ask, I've found it, you can too) Part of the reason it works is because, regardless of what others may post, it actually helps keep your body OUT of starvation mode.

This is how it works. Say you eat 2000 calories a day and you want to cut that to 1500. If you go on a long term 1500 calorie diet your body may in fact go into starvation mode and your metabolism might slow down. Now look at it from a weekly basis instead of a daily basis. You're eating 14000 calories a week and you want to cut that to 10500. That means you need to cut 3500 calories per week. If you fast two days each week and limit your food intake on those days to <250 calories each day, you've accomplished your goal. A 24-48 hour fast (with limited calories) will not put your body in starvation mode, and since you're still eating 2000 calories the rest of the week your metabolism stays high.

You may well need to cut back on very strenuous exercise while fasting to avoid eating up your lean body mass - better to do slower exercise like walking or biking that tends to pull more from your fat reserves.

Yes, a lot of what you lose in those fasts will be waste and water - which is another benefit of fasting, it allows your digestive system to empty itself. And when you start eating again you will gain that food and waste weight back as you fill your guts again. But you will also be losing fat.

Or at least that's the way it works for me. It might not work at all for you. For me, it goes like this.

I fast on Tuesdays and Wednesdays. On Tuesday I'll lose 2-3 pounds and on Wednesday I'll lose another 1-2 pounds, for a total loss of about 4 pounds. Thursday I'll get 2 of those pounds back as my gut gets refilled with food, Friday I'll gain another pound, then Saturday through Monday I'll lose one or 2 pounds as my waste system catches up, for a net loss of 1.5 - 1.8 pounds in a week.

I've been doing this for months. I haven't had a single week when I didn't lose at least 1 pound, some weeks I lose as much as 2. Energy is not a problem, in fact you may find that on your fast days you actually have more energy, especially in the afternoons since your body isn't spending energy digesting your lunch.

But, as with any diet or exercise program, what works for one doesn't necessarily work for another. Try it and see how it works for you. Certainly 24 hours of very reduced food intake is not going to hurt you.

DizzyLinds

I'm still deciding if I should fast as I'm already on a deficit from my TDEE?

Sofithomas

Fasting is awesome, look up intermittent fasting - I believe your pt is referring to this. Your body will not go into starvation mode it takes 72 hours of nothing for it to eveb start at that stage!! I fast a couple times a week and the results have been epic so far, so much leaner and more energised I think I may make it a daily thing! You still eat all your cals just in bigger meals and a smaller eating time frame - good for big appetites like me!!! ;D

myscaleaddiction

Not really advice, just sharing experience. I've tried this before twice- one day I only drank water and tea, and the second time I did it I drank both plain and lemon water. I did lose 3-4 pounds but it was only because it was the day after a binge so obviously it was water weight, as well as food weight and waste.

MoveTheMountain

This is something my PT suggested as I'm in need of fat burning. Anyone done it?

I just finished one on Monday. I do it at least once per week, and it's been great.

MoveTheMountain

I'm still deciding if I should fast as I'm already on a deficit from my TDEE?

If you feel fine and don't feel like you're not eating enough, your TDEE number might be off. The key to fasting is eating normally on the days you're not fasting. You just skip a day once or twice a week. When I fast, I don't even get hungry, although I do notice I get psychological urgest to eat, which I over ride.

DizzyLinds

I'm really not sure if my TDEE is off. Normally I'm more hungry as I'm at work..I'm a teacher so off on holiday at the moment. Also, it's so hot I've not felt like eating.

One day sounds achievable!

DizzyLinds

Bump.....

Trying this out and I've woken up starving?

DizzyLinds

bumping again....

question....when i open my fast this evening...do i eat one large meal and try and hit as high as poss on calories or do i eat a normal size meal...approx 500 cals?

bhankiii

bumping again....

question....when i open my fast this evening...do i eat one large meal and try and hit as high as poss on calories or do i eat a normal size meal...approx 500 cals?

I eat normally before the fast.

MoveTheMountain

bumping again....

question....when i open my fast this evening...do i eat one large meal and try and hit as high as poss on calories or do i eat a normal size meal...approx 500 cals?

I eat normally before the fast.

Agree. There's no prep for the fast, and there's no recovery after it. Eat a normal meal, and start the fast. Complete the fast 24 hours later with another normal meal. During the fast, drink plenty of water, but no need to go crazy - drink as you feel thirsty. Personally, I drink mostly decaf iced tea.

If you're not used to fasting, and the last few hours are really uncomfortable, it's fine to break the fast after 20 or 22 hours - especially if you feel dizzy, light-headed, really weak, etc. If you feel hungry, but otherwise you're ok, check to see if it's more of a psychological thing than a physical thing. But if you really are physically uncomfortable from hunger, then go ahead and eat. A fast is not supposed to be a miserable experience. Then, try it again in a week, and see if you can go a little bit longer.

DizzyLinds

Well my last meal wast last night and pretty big. I'm due to finish it in about 3 hours....I'm feeling crappy now...went to the shops and felt really disorientated and light headed.

rileysowner

Well my last meal wast last night and pretty big. I'm due to finish it in about 3 hours....I'm feeling crappy now...went to the shops and felt really disorientated and light headed.

How much water did you drink? I often drink 100 ounces or more on a fast day.

DizzyLinds

I measure in litres so I've had approx 2and half litres so far today.

MoveTheMountain

Well my last meal wast last night and pretty big. I'm due to finish it in about 3 hours....I'm feeling crappy now...went to the shops and felt really disorientated and light headed.

Then go ahead and eat. Wait a few days (4-7) and try it again. No one said you need to hit the full 24 hours your first time. Build up to it. (You might be carb crashing)

DizzyLinds

Sorry another question...I don't meet my macros for today then? I'm concerned I'll have eaten too many carbs too late in the day?

MoveTheMountain

Sorry another question...I don't meet my macros for today then? I'm concerned I'll have eaten too many carbs too late in the day?

If your fast occurs over 2 days (e.g., 6pm Monday - 6pm Tuesday), you definitely won't hit your macros on the second day, although you should try to get pretty close on the first day. If the fast is from 12pm Monday to 12pm Tuesday, then you'll probably get about half your macros each day. Basically, over the course of the week, you'll be down one entire day's worth of macros for that 24 hour period that you didn't eat. You definitely don't want to try to eat back any of the calories you didn't consume during the fast - that would be totally missing the point of the fast.

DizzyLinds

So that sound ok as I was on target yesterday. The only thing I'm not sure of now is that I'm already eating at a deficit...so I'm creating a bigger deficit now...which isn't good is it?

MoveTheMountain

So that sound ok as I was on target yesterday. The only thing I'm not sure of now is that I'm already eating at a deficit...so I'm creating a bigger deficit now...which isn't good is it?

How much of a deficit are you eating at now?