Fasting - Exercising

I was wondering when you were going to chime in palhaco! :wink:

Hence the saying, fat burns in a carbohydrate fire. Whith limited amounts of CHO available the process doesn’t work effectively.

A quick, cursory search in PubMed revealed this. I’m sure you can find a multitude of others, many of opposing opinions and findings, no doubt.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed

 Nutrition. 2004 Jul-Aug;20(7-8):716-27. <u>Related Articles,</u>   <u>Links</u>  ![http://www.ncbi.nlm.nih.gov/entrez/query/egifs/http:--linkinghub.elsevier.com-ihub-images-PubMedLink.gif](http://www.ncbi.nlm.nih.gov/entrez/query/egifs/http:--linkinghub.elsevier.com-ihub-images-PubMedLink.gif)  

Optimizing fat oxidation through exercise and diet.

Achten J, Jeukendrup AE.

School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom. jachten@bham.ac.uk

Interventions aimed at increasing fat metabolism could potentially reduce the symptoms of metabolic diseases such as obesity and type 2 diabetes and may have tremendous clinical relevance. Hence, an understanding of the factors that increase or decrease fat oxidation is important. Exercise intensity and duration are important determinants of fat oxidation. Fat oxidation rates increase from low to moderate intensities and then decrease when the intensity becomes high. Maximal rates of fat oxidation have been shown to be reached at intensities between 59% and 64% of maximum oxygen consumption in trained individuals and between 47% and 52% of maximum oxygen consumption in a large sample of the general population. The mode of exercise can also affect fat oxidation, with fat oxidation being higher during running than cycling. Endurance training induces a multitude of adaptations that result in increased fat oxidation. The duration and intensity of exercise training required to induce changes in fat oxidation is currently unknown. Ingestion of carbohydrate in the hours before or on commencement of exercise reduces the rate of fat oxidation significantly compared with fasted conditions, whereas fasting longer than 6 h optimizes fat oxidation. Fat oxidation rates have been shown to decrease after ingestion of high-fat diets, partly as a result of decreased glycogen stores and partly because of adaptations at the muscle level.

Publication Types: Review Review, Tutorial
PMID: 15212756

Francois -

I recently read an article (trying to find it) that mentions there are additional fat-burning gains from working out in the morning…but the benefits are not tied to whether you ate or not.

the gains you speak of are due to the elevated BMR throughout the course of the day if you workout in the morning.

you get more ā€˜bang for your buck’ so to speak from increasing your BMR @ 8am as opposed to 8pm, b/c after you head to bed…the body shuts it back down to normal.

I’m certainly no expert but here’s my opinion.

The human boy is an amazingly adaptive piece of equipment. It can survive on one or multiple fuel sources. If it has fat it will use fat if it has protein it will use that etc etc etc. If it has excess of any of teh above it will adapt to the excess…typically by storing it where it’s needed, well except protein. The body adjusts according to what it has when it has it and does the best it can with what is available.

That being said I have a REALLY hard time believing that one meal is going to make any major differences in fat burning. It may make some difference but in comparison to the long term picture, what have you been eating all week, what kind of workouts have you been doing, what type of caloric deficit/surplus are you running etc etc, eating before or after a workout jsut doesn’t seem to make a huge impact…IMO.

As another poster mentioned, calories in calories out. Lose fat by having a deficit.

As another poster mentioned, Muscle glycogen stores can not be depleted while sleeping, and another stated assuming normal diet you even have liver stores left. You may be hungry in the morning…but you’re not starving.

The anecdotal info from a couple of posters about ā€œI lost weight this wayā€ is interesting but I’d also guess if the patterns were put under the microscope of a scientific study it woudl turn out that…you guessed it they simply burnt more calories.

Think about it you get up in the AM, You run, You feel good, you’ve burnt calories. Do you go home and shovel down a ton of food? Nope not likely. More than likely you have to head off to work, your appetite is suppressed from running so you eat something significantly lighter than you would have if you had just gotten up and ate. So you have less calories going in and more going out…Voila! Magic!

Sorry for babbling but it amazes me that even in a group of people that are ā€œhealth conscienceā€ that we are still looking for the ā€œMagicā€ weightloss trick.

It’s easy…and not directed at you ā€œQuite eating so much fat @ssā€. No special workouts, time of day etc etc. No pills, Crunch lounger or Bowflex…just quite freakin’ eating so much.

~Matt

This may seem ridiculous but could working out in the evening, having a light meal and then fasting over night and then workout in the morning cause some of the same adaptations of this study? Or, could just exercising in the morning after an overnight fast do the same? I realize this is reaching.

Skeletal muscle adaptation: training twice every second day versus training once daily.

Hansen AK, Fischer C, Plomgaard P, Andersen JL, Saltin B, Pedersen BK.

Department of Infectious Diseases, The Copenhagen Muscle Research Centre, Rigshospital, Copenhagen, Denmark.

J Appl Physiol 2004 Sep: 10 Low muscle glycogen content has been demonstrated to enhance transcription of a number of genes involved in training adaptation. These results made us speculate that training at a low muscle glycogen content would enhance training adaptation. We therefore performed a study in which seven healthy untrained males performed one-knee legged exercise training at a low glycogen (Low) protocol, whereas the other leg was trained at a high glycogen (High) protocol. Both legs were trained equally regarding workload and training amount. Day one: Both legs (Low+High) were trained for 1 h followed by 2 h of rest at a fasting state, where after one leg (Low) was trained for one more hour. Day 2: Only one leg (High) trained for 1 h. Days 1 and 2 were repeated for 10 weeks. As an effect of training, the increase in maximal workload was identical for the two legs. However, time till exhaustion at 90% was markedly more increased in the Low leg compared with the High leg. Resting muscle glycogen and the activity of the mitochondrial enzyme hydroxyacyl CoA dehydrogenase (HAD) increased with training, but only significantly so in LOW, whereas citrate synthase (CS) activity increased in both low and high. There was a more pronounced increase in CS activity when Low was compared with High. In conclusion, the present study suggests that training twice every second day may be superior to daily training.

i think it’s important to eat at least something. for me I can’t even run a 3 miler without at least having a banana or something. it’s quite discouraging to run or do anything without any gas in the tank…there is just no energy there to do anything.

Body For Life recommends doing a morning workout prior to eating. it seems so stupid to me.

I think Noakes’ ā€œLore of Runningā€ has a section that summarises research concerning this kind of question, and also discusses the idea of ā€œfat loadingā€ before an event. Can’t remember anything in sufficient detail… Could look it up later…

actually, I am 5’7.5’’ and currently 144lbs so it’s not like I have tons to lose anyway…just trying to get to 140lbs just for race day to run really well.

<< for me I can’t even run a 3 miler without at least having a banana or something >>

That’s psychological. You, me, and any other reasonably trained & fit individual can run a lot more than 3m on an empty stomach.

<< Body For Life recommends doing a morning workout prior to eating. it seems so stupid to me. >>

Well, if nothing else, it gets you (generic you, not you personally) to work out, rather than strapping on the feed bag first thing. I should preuse my copy of BFL and see if they quote any research studies that ā€œproveā€ this fact, I’m prety sure I remember him mentioning at least one such study.

I do the empty stomach am workout thing all the time. Works fine for me. I’ve set numerous PR’s in training workouts doing this, on everything from 4m to 16m runs, and on bike rides of up to 2 hours as well. Just this past Saturday I knocked over 30 secs offa my hillclimb PR on nothing but some water, and the previous one had been set after eating (I rode later in the day that time). Once I get up near or over 2 hours, I need some fuel, so I’ll hit a GU or equivalent then, but for anything less, I’m fine w/ just water, or nothing.

You avoid many GI issues (cramping, bloating, gas, etc) by exercising on an empty stomach. At least I have found that to be the case. That’s my story, and I’m sticking with it. :wink:

I pretty much new that and why I said not directed at you.

It’s just surprising to me that we seem to complicate things so much sometimes. I guess we all do it with different aspects.

Seems people will sometimes go thru all sorts of twists and turns, experiments and trials when there is such an easy straight forward definitive method.

At one time I lost a significant amount of weight. I actually had one guy ask me how I did it. I answered with ā€œI quite eating so muchā€. His response was ā€œNo really what’d ya do, Weight watchers, Atkins, etc etcā€. Again I respondedā€¦ā€œI quite eating so muchā€. The guy was almost pissed at me, like I was holding onto some deep dark secret I refused to share.

I guess my point is weight loss is very simple, eat less and eventually you’ll lose weight. It works 100% of the time, It’s not complicated, doesn’t require special food, training, eating, machines, schedules…just less food.

~Matt

This is a perfect example illustrating the point that this is a phenomenon that is highly based on individual preferences.

Ok, so I’ve had a look in Noakes and this is a summary vis a vis fat metabolism:

It is believed that the amount of energy muscles can extract from fat metabolism during exercise is determined by the free fatty acid levels in the blood. These levels in turn depend on the muscle glycogen content - if the muscle glycogen content is low the free fatty acid concentrations are high and vice versa. So, the carbohydrate metabolism regulates the fat metabolism. However, the reverse is not true, so ingesting fatty acids does not promote fat metabolism. ā€œThe practical point is that any carbohydrate ingested before exercise increases the amount of carbohydrate used during subsequent exercise… The effect is measurable for about 6 hours after a high-carbohydrate meal… Thereafter, people’s metabolism during exercise would be the same as if they had fasted for 12 to 14 hours.ā€

but doesn’t coffee stimulate the release of FFA in the blood, and therefore a morning session after a coffee (no milk, no sugar) could promote fat metabolism.

Big Cheese?

Also from Noakes:

ā€œCaffeine ingestion appears to have no metabolic value… caffeine does not appear to increase fat metabolism… caffeine may indeed have increased fat use by the muscles and spared muscle glycogen use… but this … seems unlikely because caffeine enhances performance during high-intensity exercise at VO2max without affecting the rate of muscle glycogen use… A number of studies show that endurance performance is increased after caffeine ingestion without evidence of increased whole body fat metabolism with carbohydrate sparing.ā€

Other points: Unlike in time-to-failure tests, when Noakes et al tried a time trial they could find no caffeine effect. If you do want to use caffeine, coffee appears a poor choice since other substances in coffee prevent the usual ergogenic effect of caffeine.

I really suggest you trying the fasting technique on the 29th of May :slight_smile:
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yeah right :slight_smile:
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Even though cafeine improves performance, that does not happen because of the release of FFA to the blood and increased fat metabolism. Duncan has Noakes’ book handy, he can quote that part, mine is at home :slight_smile:

maybe I shoudl read that WHOLE book since I have it :slight_smile:
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