energy substrate useage

[Pegasus AdministratorPE Gym EditorPEGym Hero ☺ Admin of the Month Mar 2015 Find all posts View Profile Close Pegasus]

There seems to have been some interest in and misunderstanding of energy substrate usage onsite recently .

Ok energy is broken down in the body to provide energy which is then burned. The body can use carbs or fat or in some cases protein . Where this energy at base comes from depends on a number of factors . One of them is intensity of exercise . It has been discovered that you can increase fat use during high intensity exercise for instance by exhausting carbs stores .

Now the myth has grown up that it is REQUIRED to exhaust carb stores in order to use fat for energy . This i not so . Now it may be a worthwhile thing to do in some circumstances like you are an avid gymgoer who want to lose weight and have limited exercise time . But that is not the question .

The body gets it's energy during things like a walk largely from fat it is quite possible to lose weight without exhausting carb stores . Now it may not suit your typical gymgoer but that is not the question either .

The question is this .
Is exhaustion of carb stores required to lose fat ? The answer is no.

[Pegasus AdministratorPE Gym EditorPEGym Hero ☺ Admin of the Month Mar 2015 Find all posts View Profile Close Pegasus]

The body burns fat throught the day as a fuel source along with carbs ,it is a normal energy source . Of course most of us take in enough calorie to replace this and more . So we are told to exercise and eat less . On the exercise front if you go for a walk the calories will come mostly from fat . However as the intesity rises the body increases the % coming from carbs it's prefered fuel source for intense work. This will continue until the body stores are depleted at which time the % of calories coming from fat will again rise .

So it certain circumstances it can be advantageous to deplete carb stores and this is supported by science . The gymcrowd often don't take in the full story and the myth has grown up you need to deplete carb stores to lose weight . This misinfo is commonly passed on.

I invited guys to research guess what happened ?
Guys have found the science supporting increased fat use in carb depleted states at high effort levels ignored the rest and continue to believe it is required . Required not useful in some situations .

Take this scenario .
Wendy does little exercise and eats a typical western diet and is stressed at work.
She has gained a few pounds and is frazzled .
She decides to go on a month long yoga retreat . They eat quality vegan food with lots of carbs and of course the yoga never fully depletes the carb stores anyway. Now bet my bottom dollar at the end of the month she has significant weight loss without ever having fully depleted her carb stores .
THe reason is calories out increased calories in decreased and body fat stores were mobilised and burned .

[Pegasus AdministratorPE Gym EditorPEGym Hero ☺ Admin of the Month Mar 2015 Find all posts View Profile Close Pegasus]

Now for those interested here is the tek stuff . You can find this info easy enough all over the web and the supporting studies sorry I do not have the time for further . They will just repeat this anyway .
Quote
5.1. Substrate utilization during exercise in fasted stateCHOs (muscle glycogen and plasma glucose) and fats (plasmafatty acids and intramuscular triglyceride) are thus the primaryenergy sources during exercise. The proportions of their contribution to energy expenditure are determined largely by the intensityand duration of substrate utilization.In fasted state during low intensity exercise (25% of maximal O2uptake (VO2max)), which corresponds to walking at 4e5 km/h, mostof the energy need is provided by oxidation of fatty acids of whichmore than 85% is derived from plasma.55 At this intensity, the rate ofappearance of fatty acids in plasma is very similar to the rate of fattyacid oxidation (i.e. lipolysis from adipocytes) (w26 mmol/kg/min).The rate of fatty acid oxidation is determined from direct measuresof the rate of appearance (Ra) of glycerol, which is an index oflipolysis (defined as 3 glycerol Ra, as 3 fatty acids and 1 glycerolmolecule are released from 1 triglyceride during lipolysis).As the exercise intensity increases to a moderate level (65%VO2max), use of plasma fatty acids decrease while the intramuscular triglycerides oxidation increases (Fig. 4). At this level, plasmafatty acids and intramuscular triglycerides contribute equally tototal fat oxidation. Although the total fat oxidation is highest at thisexercise level (>40 mmol/kg/min), fat cannot be oxidized at sufficiently high rates to provide all the energy required. Consequently,about one-half of the total energy is simultaneously derived fromCHO oxidation (muscle glycogen and blood glucose).56At high exercise intensities level (85% of VO2max), the rate ofplasma fatty acid oxidation is decreased below the value at 65% ofVO2max, and intramuscular triglycerides become the major sourceof fatty acids for oxidation. The intramuscular triglycerides releasefatty acids directly into the cytosol of working muscle, avoidinghaving to transfer the muscle plasma membrane, which makesthem a very attractive potential energy source. Concerning longchain fatty acids, they become trapped in adipose tissue as exerciseintensity increases, presumably because of insufficient albumindelivery to carry them from adipose tissue into the systemiccirculation.57 It cannot be excluded that during high intensityexercise free carnitine (which transports the long-chain fatty acidsinto the mitochondria so they can be oxidized) concentrationdeclines to a value that could limit carnitine palmitoyl transferaseactivity and reduce the long-chain fatty-acid oxidation.58 Theoxidation of medium chain fatty acids (i.e. those primarily containing fatty acids with 8e10 carbon atoms) seems to be lessinhibited because they are transported differently into the mitochondria by using a different enzyme complex (carnitine octanoyltransferase). As a consequence, part of the medium chain fatty acidscan freely diffuse into the mitochondria.59The availability of plasma fatty acids decreases despite a maintained high rate of lipolysis from adipocytes. When the intensity ofexercise reaches 85% VO2max, the absolute rate of fat oxidationdecreases (from >40 to 30 mmol/kg/min), and the CHO oxidationprovides more than two-thirds of the energy required. Theadvantage of CHO metabolism during high intensity exercise lies inits two times more rapid energy transfer capacity compared withfatty acids.51 These data have been collected in endurance trainedsubjects after 10e12 h fast and 30 min exercise.5.2. Substrate utilization during exercise in non-fasted stateCHO meals and their importance for exercise performance havebeen recognized since the classic respiratory exchange studies ofChristensen and Hansen in the late 1930s,60 and the biopsy studiesof Bergstrom et al. in 1967.61Typically, the rate of CHO oxidation is elevated during prolongedexercise after a CHO meal compared with exercise after fasting.62The ingestion of a CHO-rich meal before exercise has been shownto increase muscle glycogen, blunt fatty acid mobilization andenhance exercise performance.60,63e65 The improvements inperformance following CHO ingestion were shown to result fromthe maintenance of blood glucose late in exercise. In particular, low

[Pegasus AdministratorPE Gym EditorPEGym Hero ☺ Admin of the Month Mar 2015 Find all posts View Profile Close Pegasus]

Ok so lets look at this part \
quote
The proportions of their contribution to energy expenditure are determined largely by the intensityand duration of substrate utilization.In fasted state during low intensity exercise (25% of maximal O2uptake (VO2max)), which corresponds to walking at 4e5 km/h, mostof the energy need is provided by oxidation of fatty acids of whichmore than 85% is derived from plasma.55 At this intensity, the rate ofappearance of fatty acids in plasma is very similar to the rate of fattyacid oxidation (i.e. lipolysis from adipocytes) (w26 mmol/kg/min).The rate of fatty acid oxidation is determined from direct measuresof the rate of appearance (Ra) of glycerol, which is an index oflipolysis (defined as 3 glycerol Ra, as 3 fatty acids and 1 glycerolmolecule are released from 1 triglyceride during lipolysis).As the exercise intensity increases to a moderate level (65%VO2max), use of plasma fatty acids decrease while the intramuscular triglycerides oxidation increases (Fig. 4). At this level, plasmafatty acids and intramuscular triglycerides contribute equally tototal fat oxidation. Although the total fat oxidation is highest at thisexercise level (>40 mmol/kg/min), fat cannot be oxidized at sufficiently high rates to provide all the energy required. Consequently,about one-half of the total energy is simultaneously derived fromCHO oxidation (muscle glycogen and blood glucose)
Unquote
So if you go for a walk at 4 to 5kmph (typical walking pace) most energy is provided by fat . Start joging and about half comes from carbs and half from fat . As exercise intensity increases so does carb use unless of course carbs are exhausted .

[Pegasus AdministratorPE Gym EditorPEGym Hero ☺ Admin of the Month Mar 2015 Find all posts View Profile Close Pegasus]

So 2 scenarios .

Fred is 75 years and lives in a retairment home he has gained a few pounds . He decides to avoid choc cake and go for a walk each morn . Does he worry about trying to exhaust carb stores hell no . Is it likely to work if he keeps doing it hell yes . Why? Calories in have gone down calories out have gone up and he is buring fat during his walk .

John is an avid gymgoer who has "bulked up" . He decides to do some cardio to burn calories gets on the bike and does long hard session and cuts his "bulking" diet . During the early parts of his ride carbs are mostly used but as they are exhausted John realises he gets more fat burning .
Now young fit John has actually burned AS A % LESS OF HIS CALORIES than Fred from fat. However he loses weight quicker because he has burned MORE TOTAL CALORIES . Including possibly more from fat .
So is this workout suitable for Johm hell yes .
Why? It suits him and he is able to do it . He has fewer calories in more calories out and in fact is likely to get a quicker change than the other scenarios .

[Johnny D ModeratorPEGym Hero Find all posts View Profile Close Johnny D]

But at 25%VO2max, it's gonna take a lot of work to reach the desired calories out, isn't it? I mean, I'd rather shred for 20 minutes on the bike than walk for hours. And I suppose the **** followers would say that you can continue to burn fat at any level of output if you're fat adapted.

[Pegasus AdministratorPE Gym EditorPEGym Hero ☺ Admin of the Month Mar 2015 Find all posts View Profile Close Pegasus]

But at 25%VO2max, it's gonna take a lot of work to reach the desired calories out, isn't it? I mean, I'd rather shred for 20 minutes on the bike than walk for hours. And I suppose the **** followers would say that you can continue to burn fat at any level of output if you're fat adapted.

Hey I have given scenarios in which different things work depending on the situation choose whichever you like.

[Pegasus AdministratorPE Gym EditorPEGym Hero ☺ Admin of the Month Mar 2015 Find all posts View Profile Close Pegasus]

Look I have made this simple anyone that doesn't understand probably just doesn't want to .

However if there is a genuine case where you need something explained just post

[Johnny D ModeratorPEGym Hero Find all posts View Profile Close Johnny D]

Hey I have given scenarios in which different things work depending on the situation choose whichever you like.

Totally agree. Fair enough. I like what you posted and was just adding a perspective of my own.

BTW... Why did it auto convert to "****"? I searched around other threads and couldn't find an answer but see that it happens every time.

[Big Al AdministratorPEGym EditorMale Enhancement Coach Rep.PEGym Hero Find all posts View Profile Close Big Al]

Totally agree. Fair enough. I like what you posted and was just adding a perspective of my own.

BTW... Why did it auto convert to "****"? I searched around other threads and couldn't find an answer but see that it happens every time.

That word (k e t o) appears blocked due to spam filters.

[Pegasus AdministratorPE Gym EditorPEGym Hero ☺ Admin of the Month Mar 2015 Find all posts View Profile Close Pegasus]

But at 25%VO2max, it's gonna take a lot of work to reach the desired calories out, isn't it? I mean, I'd rather shred for 20 minutes on the bike than walk for hours. And I suppose the **** followers would say that you can continue to burn fat at any level of output if you're fat adapted.

By the by if you did a hard out 20 min bike ride most of the calories would likely come from carbs.

[CUSP82 Administrator Admin of the Month Dec 2014PEGym Hero Find all posts View Profile Close CUSP82]

Great info; thanks!

[Johnny D ModeratorPEGym Hero Find all posts View Profile Close Johnny D]

By the by if you did a hard out 20 min bike ride most of the calories would likely come from carbs.

Pretty interesting stuff. I'd like to find some controlled studies to see the results. Keep all else equal - nutrition, other activities, etc... - and compare body fat percentage loss across groups who only change for intensity of workouts. Do the 65%+ VO2Max participants just deplete glycogen stores, while the 25% VO2Max participants end up lowering overall body fat? Would be cool to see that.

[Pegasus AdministratorPE Gym EditorPEGym Hero ☺ Admin of the Month Mar 2015 Find all posts View Profile Close Pegasus]

Pretty interesting stuff. I'd like to find some controlled studies to see the results. Keep all else equal - nutrition, other activities, etc... - and compare body fat percentage loss across groups who only change for intensity of workouts. Do the 65%+ VO2Max participants just deplete glycogen stores, while the 25% VO2Max participants end up lowering overall body fat? Would be cool to see that.

The point was they could all lose bodyfat .
I would suggest the thres examples showed different people doing different things all having success because they did what suited them. More intense workouts are more effectivr per unit of time but tht is not the only factor .

[D6ggy9tyle Senior Member Member of the Month April 2019 Find all posts View Profile Close D6ggy9tyle]

<insult removed by Senior Admin, more here:
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Your yoga example was rediculous. For a few reasons. A. You clearly don't understand the intensity of most yoga. Even slower hatha yoga involves a lot of intensity. B. Diet change is a variable that negates your point. Any proper diet and activity of more calories out vs in will lose weight. C. Yoga retriets are long days of many sessions, this means many many burned calories. D. This is just your random hypothetical input anyway. F. Have you been to a yoga retreat? Most people who do a lot of yoga, are not extremely fit or low body fat. They have bodies similar to runners. Solid Type 1 muscle fibers with lots of stability and endurance, very little Type 2. Tend to have a bit of flabbyness.

You're trying to push this idea that if you just walk consistantly without changing anything else, without changing diet, without doing more intense excersize, without doing cardio that depletes glycogen and turns to fat metabolization, or weight training to build muscle, that just walking will make you lose weight.

Walking burns about 250 calories per hour for the avg person. Your saying this is mostly from fat. It takes 3500 calories of fat metabolized per lb. So to your theory, if you just walk around throughout your day for at least 2 hours, which basically everyone does, you should be losing a pound or more a week directly from fat....