Does High Intensity Training Help with Fat Loss?

Training
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[quote]Magnetic88 wrote:
Maybe I should try to explain the reasoning a little better (and please, be as critical as possible here as it’s just a theory):

I’m not saying that fast-twitch muscle concentration efficiently burns fat. Yes slow-twitch fibers use fat for fuel so it would stand to reason that having more of them would burn more fat… BUT…

Consider that your body is always trying to maintain homeostasis. When you see runners who at first see great results in fat loss and then develop a rail-body with a “loose covering”, I think what is happening there is that most of their muscle fibers have switched to slow-twitch. Now consider their situation: they are constantly in need of fats for fuel and yet they do not have it. What is the body to do? It stands to reason that it will try to self regulate. It will make you crave fatty foods and/or it will try to retain as much fat as possible since it knows that it will be needed for your 7-days-a-week 3am marathon training. It thinks that your running is the new normal and so it will try to adjust to this new normal by giving you a normal bodyfat percentage in whatever way it can. If you weren’t using your type-1 fibers so much, the body wouldn’t really care whether you have fat or not, but you do and it does. When you stop running, you are screwed.

Now lets take weight training: you are using far more fast-twitch muscles and they are utilizing your glucose. This, in theory, would effect fat composition in three ways. Firstly, it is using those sugars as energy and therefore it doesn’t get stored in the body as fat (so in that respect, you MIGHT AS WELL be burning straight fat). Secondly, your body doesn’t have the NEED for fat in order for it to successfully do what you’re telling it to do. Thirdly, it is causing a shift toward more fast-twitch muscle, by high intensity training, you are setting up a positive feedback loop rather than a situation that the body is always trying to correct. AGAIN: this is just one guy’s hypothesis.

I have a high concentration of fast-twitch muscle and have always found it nearly impossible to get fat. A friend of mine is a typical “skinny-fat” person. If you asked him to throw a punch you would be singing christmas carols before it landed. Another friend was very fat and very slow… however he got very skinny around age 19 and stayed that way into his 30’s. It would be logical that he would now be quite quick and strong since he isn’t wearing a fat-suit, but no, he couldn’t generate an explosive movement if his life depended on it. Thinking back, I think he was one of those sad people that are cursed with almost no fast-twitch muscle. Is it that fat people are slow because they’re fat, like we have always thought, OR could it be that they are fat because they’re slow… hmmm…

We know that sprinters have some of the highest concentrations of fast-twitch muscle. I don’t know any fat sprinters. Yes they do alot of training but I would say that they don’t necessarily train any harder than a marathoner. Not that marathoners are fat… but some of them have a harder time losing weight.

Looking around, it seems that the more explosive a person is, the leaner they tend to be. Correlation is not causation of course!

Sorry for the essay, I just wanted to put forth the reasoning behind previous statements related to muscle fibers. I apologize susani if this qualifies as thread hijacking.
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Couple of things. Slow twitch muscles are efficient at using fuel in an oxidative state, which could be aerobic glycolysis OR fat oxidation. Which they prefer depends on enzymes and normal diet, so a marathon runner that eats a ton of carbs is great at burning carbs, whereas one in ketosis is more efficient at using fat (and ketone bodies).

And to play devils advocate, does this guy look explosive? Given that he has a 472.5 kg snatch and C&J total! Yet he is carrying a lot of body fat. I am guessing he has more fast twitch muscles than you and I combined.

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[quote]Ecchastang wrote:

[quote]Magnetic88 wrote:
Maybe I should try to explain the reasoning a little better (and please, be as critical as possible here as it’s just a theory):

I’m not saying that fast-twitch muscle concentration efficiently burns fat. Yes slow-twitch fibers use fat for fuel so it would stand to reason that having more of them would burn more fat… BUT…

Consider that your body is always trying to maintain homeostasis. When you see runners who at first see great results in fat loss and then develop a rail-body with a “loose covering”, I think what is happening there is that most of their muscle fibers have switched to slow-twitch. Now consider their situation: they are constantly in need of fats for fuel and yet they do not have it. What is the body to do? It stands to reason that it will try to self regulate. It will make you crave fatty foods and/or it will try to retain as much fat as possible since it knows that it will be needed for your 7-days-a-week 3am marathon training. It thinks that your running is the new normal and so it will try to adjust to this new normal by giving you a normal bodyfat percentage in whatever way it can. If you weren’t using your type-1 fibers so much, the body wouldn’t really care whether you have fat or not, but you do and it does. When you stop running, you are screwed.

Now lets take weight training: you are using far more fast-twitch muscles and they are utilizing your glucose. This, in theory, would effect fat composition in three ways. Firstly, it is using those sugars as energy and therefore it doesn’t get stored in the body as fat (so in that respect, you MIGHT AS WELL be burning straight fat). Secondly, your body doesn’t have the NEED for fat in order for it to successfully do what you’re telling it to do. Thirdly, it is causing a shift toward more fast-twitch muscle, by high intensity training, you are setting up a positive feedback loop rather than a situation that the body is always trying to correct. AGAIN: this is just one guy’s hypothesis.

I have a high concentration of fast-twitch muscle and have always found it nearly impossible to get fat. A friend of mine is a typical “skinny-fat” person. If you asked him to throw a punch you would be singing christmas carols before it landed. Another friend was very fat and very slow… however he got very skinny around age 19 and stayed that way into his 30’s. It would be logical that he would now be quite quick and strong since he isn’t wearing a fat-suit, but no, he couldn’t generate an explosive movement if his life depended on it. Thinking back, I think he was one of those sad people that are cursed with almost no fast-twitch muscle. Is it that fat people are slow because they’re fat, like we have always thought, OR could it be that they are fat because they’re slow… hmmm…

We know that sprinters have some of the highest concentrations of fast-twitch muscle. I don’t know any fat sprinters. Yes they do alot of training but I would say that they don’t necessarily train any harder than a marathoner. Not that marathoners are fat… but some of them have a harder time losing weight.

Looking around, it seems that the more explosive a person is, the leaner they tend to be. Correlation is not causation of course!

Sorry for the essay, I just wanted to put forth the reasoning behind previous statements related to muscle fibers. I apologize susani if this qualifies as thread hijacking.
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Couple of things. Slow twitch muscles are efficient at using fuel in an oxidative state, which could be aerobic glycolysis OR fat oxidation. Which they prefer depends on enzymes and normal diet, so a marathon runner that eats a ton of carbs is great at burning carbs, whereas one in ketosis is more efficient at using fat (and ketone bodies).

And to play devils advocate, does this guy look explosive? Given that he has a 472.5 kg snatch and C&J total! Yet he is carrying a lot of body fat. I am guessing he has more fast twitch muscles than you and I combined.
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Lol so true. The explosiveness of those Olympic lifters is terrifying.

Way to many factors to try and say fast and slow fibers dictate leanness. Jusr like it’s not just diet or cardio. And fibers don’t just switch back and forth just by training a bit differently. It’s no that easy or fast

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Good points. I think it’s safe to say that diet has the most profound effect on bodyfat.

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RyanbCXG, I started that at 173# ! at 73" tall. So yeah…
I ate in protein what I wanted to weight in pounds plus 10%. So about 230-250gr/day.

TWO solid years of weight releasers, chains and band via Westside program !
Never missed a day of TRAINING, never missed a good nights sleep, stayed on top of my life.

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EPOC is not that significant and is actually an outdated model. Lactate metabolism, phosphate resynthesis and fatty acid cycling, along with increases in catecholamine levels are likely the cause of the post-exercise calorie burn.

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I’ll google that jp_dubya so thanks for the pointers! But if you can expand on it at all that too would be great!

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Thinking about what you’ve said though - research (reliable, accurate research by all accounts) has ruled out post-exercise calorie burn. It doesn’t really happen. Not to any significant degree. So it’s not a matter of figuring out what causes it - it doesn’t happen. Period.

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[quote]susani wrote:
Thinking about what you’ve said though - research (reliable, accurate research by all accounts) has ruled out post-exercise calorie burn. It doesn’t really happen. Not to any significant degree. So it’s not a matter of figuring out what causes it - it doesn’t happen. Period.
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And yet study after study comparing HIIT to LISS shows participants lose more weight on HIIT even though calorie burn during exercise can be more with LISS. The human body is far more complicated than just calorie in/calorie out.

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[quote]Ecchastang wrote:

[quote]susani wrote:
Thinking about what you’ve said though - research (reliable, accurate research by all accounts) has ruled out post-exercise calorie burn. It doesn’t really happen. Not to any significant degree. So it’s not a matter of figuring out what causes it - it doesn’t happen. Period.
[/quote]
And yet study after study comparing HIIT to LISS shows participants lose more weight on HIIT even though calorie burn during exercise can be more with LISS. The human body is far more complicated than just calorie in/calorie out. [/quote]

It’s still calories in and out but we are just unable at this point to accurately calculate those sides. But rest assured it is cal in vs out.

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Since I can only say what works on me and really that’s all that matters to me since everyone is so different but may give other ideas of things to tweak or try. Fasted walking or light elyptical has been the best thing for me to maintain what I call an ok bf level while gaining weight or losing fat depending on what I want.

All the while eating a lot of food. Way more food than the calorie counts say I am burning. 3-5x as many I am burning and some days 10x higher yet my body never wanders far from my bf level. Just my observation. I’ve tried it with hiit and the results weren’t as good and recovery got horrible.

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[quote]ryanbCXG wrote:

[quote]Ecchastang wrote:

[quote]susani wrote:
Thinking about what you’ve said though - research (reliable, accurate research by all accounts) has ruled out post-exercise calorie burn. It doesn’t really happen. Not to any significant degree. So it’s not a matter of figuring out what causes it - it doesn’t happen. Period.
[/quote]
And yet study after study comparing HIIT to LISS shows participants lose more weight on HIIT even though calorie burn during exercise can be more with LISS. The human body is far more complicated than just calorie in/calorie out. [/quote]

It’s still calories in and out but we are just unable at this point to accurately calculate those sides. But rest assured it is cal in vs out. [/quote]
Yes, it is calories in/calories out, but trying to get all calculated doesn’t work. I hear all the time people write that for X weight, eat Y calories. I don’t count calories, but when I do it is upwards of 3500 kcal every day, many times much much more. Yet, I have one of the advanced heartrate monitor GPS watches that also calculates calorie expenditure off of movement AND what your heartrate does, and both times I have worn it for 24 hrs straight, it tells me I burn about 2200 kcal. Yet most people would get fat off of the amount I eat.

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I see that you guys are in agreement, but I’d just like to echo your sentiments that the explanation lies in our inability to accurately calculate caloric expenditure on an individual basis, not in our bodies’ ability to defy the laws of thermodynamics (which, as comical as it may seem, is a theory supported by many people these days).

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Say I consume 2,000 calories per day and (reliable) testing of oxygen consumption proves that I’m burning exactly 2,000 calories a day. This includes the calorie burn from a daily 60 minute jog. My weight stays constant.

I switch my daily jog to a short high intensity sprint session. All other variables remain the same - I consume 2,000 calories and testing shows I burn 2,000 calories. Yet I loose weight and fat levels drop.

That seems to be the situation that the research is saying is happening - and it seems like an impossibility.

Testing calorie burn in terms of oxygen consumption is apparently very reliable and it will detect calorie burn from any source. So how is that fat being lost?

If we eat too many calories it either becomes fat or (if we train the right way) muscle. It seems to me that the only thing that can be happening (if we’re loosing fat) is we must be building muscle.

We know high intensity training increases growth hormone levels - and other changes that promote muscle growth.

So - an extreme example, but it makes it easier to do the sums:

Imagine the high intensity intervals allow me to build more muscle - half a pound a week. That equates to 3,500 calories a week or 500 calories a day. That leaves me with just 1,500 calories from my daily intake but I need 2,000. So the remainder has to come from fat stores. Now I realise the process of building muscle will involve a certain amount of calorie burn, but some of it just gets stored as muscle - in the same way as excess calories turn to fat.

This would also explain why bodybuilders and so on get such great results but a lot of women claim it doesn’t work well for them. The former have huge potential to pack on muscle - so lots of potential for calories to be diverted to muscle growth. Less potential for this with women - although it can still give good results. I’ve always felt good in high intensity training and feel good on it - but I’m not sure I do burn much fat on it. I need the longer haul stuff for that. I need both.

That’s my best guess right now. Which has got me wondering if high intensity training is best for me given that I’m not wanting to build too much muscle mass. It’s packing on a bit faster than I’d like at the moment!!!

Edit: Of course, the big flaw in my theory is you wouldn’t loose weight if you were packing on muscle!! Just realised that!

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[quote]susani wrote:
That equates to 3,500 calories a week or 500 calories a day. That leaves me with just 1,500 calories from my daily intake but I need 2,000. So the remainder has to come from fat stores.[/quote]

I would revisit that last sentence. I think a more useful model is to say that the remainder MAY come from fat stores, and that by altering dietary and training choices, you can bias things so that more or less can come from fat stores.

It’s generally more useful to view the body using a probabilistic model than a discrete one.

There are many sources of energy and many forms of energy sources. For example, in order for fat stores to be used as fuel, they usually need to be broken down into a form that can be transported through the bloodstream. If there are already free-floating amino acids or sugars in the bloodstream, the body may preferentially use those as energy sources before expending the effort to break down fat tissue.

Likewise, certain supplements can increase “fat/lipid mobilization” and make it more likely that they will be used as an energy source. As well as concepts like high-fat diets so that the body adapts to a high concentration of lipids in the bloodstream and ramps up the biochemical machinery to process and live off fats.

Additionally, oxygen consumption may be one of the better methods we have for measuring metabolic activity, but that doesn’t mean it’s anywhere near complete in its coverage of all the various systems involved.

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[quote]susani wrote:
That’s my best guess right now. Which has got me wondering if high intensity training is best for me given that I’m not wanting to build too much muscle mass. It’s packing on a bit faster than I’d like at the moment!!![/quote]
If this is a legitimate concern, the obvious solution is to cut back on your training, not the HIIT.

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[quote]LoRez wrote:
Additionally, oxygen consumption may be one of the better methods we have for measuring metabolic activity, but that doesn’t mean it’s anywhere near complete in its coverage of all the various systems involved.[/quote]

From what I’ve been reading oxygen consumption really is the be all and end all when it comes to measuring calorie burn. Anything that happening in the body that burns calories increases oxygen consumption - the one or two minor things that can occur without increase oxygen consumption are so short lived (not sustainable) that their contribution is insignificant. Or so I’ve read!

Your other comments are interesting. I’ll do a bit of googling and try and understand all those points a bit better. Thank you!

[quote]LoRez wrote:

[quote]susani wrote:
That’s my best guess right now. Which has got me wondering if high intensity training is best for me given that I’m not wanting to build too much muscle mass. It’s packing on a bit faster than I’d like at the moment!!![/quote]
If this is a legitimate concern, the obvious solution is to cut back on your training, not the HIIT.[/quote]

Cutting back on training to avoid mass gain might be a solution if your purpose for training is purely aesthetic. It’s all about performance -gymnastics skills / calisthenics for me. It’s very tricky to build strength whilst keeping weight down. Currently I’m doing a lot of pullups, flags, levers - as well as making good progress in deadlifts & squats.

Around March I got my weight down to 63kg - I’d figured I could lose a bit more fat and expected to be at 61kg now. Being that couple of KG lighter is a big help when you’re doing bodyweight routines. Instead I now weigh 66kg despite having reduced fat levels. I’m already doing what I can to try and stick to training methods that result in neural adaptation rather than mass gain. It’s slow muscle gain but it’s not showing any signs of stopping yet!

I’m not dead against mass gain. It’s getting the balance right - as long as relative strength keeps going up (which it is) then it’s not a problem. Would it go up faster if I kept muscle mass down? The only way to find out is to try it.

As one of the major selling points of hiit over longer duration cardio is that it helps to build muscle. It makes sense then to experiment with longer duration cardio if you want to gain strength without mass. I have been adding more long duration stuff in (which I think helped to cut fat levels). I haven’t yet tried cutting some of the hiit out - it goes against the grain…I LOVE how it makes me feel and I really do want the type of fitness it devlops. But I might need to give it a try.

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A really good article here that explains how calorie burn can be reliably calculated by measuring oxygen consumption. It explains how they know that nothing is burning calories without a corresponding increase in oxygen consumption:

http://www.unm.edu/~lkravitz/Article%20folder/caloricexp.html

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[quote]Ecchastang wrote:

[quote]susani wrote:

But if you need to burn calories to shed excess fat and you are unwilling or unable to cut back on food intake then long duration, lower intensity training is your best bet.
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That is completely false. 1994 study had participants do 20 weeks of steady state aerobic training or 15 weeks of sprint intervals. (15 thirty second sprints). Sprint group lost more fat.

2010 study found 6 sessions of 6 thirty second all out cycle sprints with 4 min rest over 2 weeks led to 3cm waist reduction. Sprints have been shown to increase GH, whereas slow steady state causes a reduction in testosterone.

2011 study show sprints increase stroke volume and reduce resting heart rate.

Sprints have a greater impact on cholesterol profile as well, and improve maximum lung capacity.

2011 Journal of Obesity review shows that “regular aerobic exercise on body fat is negligible.” And that high intensity intermittent exercise, which is anaerobic in nature is more effective .

The purpose of Aerobic exercise is to train the body to be as efficient as possible.

2006 study of runners over a 9 year period showed that only runners that tripled their mileage over the time (from 16km per week to 64 km per week) did NOT gain fat.

Duke University 13 week study had men do either 30 minutes of cardio or 60 minutes of cardio, and the 30 min group lost 4kg, the 60 lost 3.8kg.

The research will prove you wrong time and time again on which is more effective for fat loss.
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it means doing rest pause training will lose fat more than traditional training since rest pause training is HIIT?

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In isolation these studies are misleading and incomplete. And they contradict each other!

Calorie burn can be reliably calculated according to oxygen consumption. So a simple way to think about it is this - the more oxygen you consume the more calories you burn. Walking or jogging (if you’re fit and walking / jogging are very easy for you) will burn next to no calories as it won’t increase oxygen consumption much above what you’d use sitting about doing nothing.

Very short sprints will result in the greatest oxygen consumption but you’ll only keep it up for a matter of seconds. Repeat those sprints taking short recoveries and you’ll be able to get oxygen consumption up to a higher level because a) you’re repeating the task several times, and b) you’ll still be gasping for oxygen during your rest periods as your body tries to replenish everything. However, at such high levels of exertion the amount of time that you can keep it up is limited.

Lower the intensity and you’ll be able to keep going for longer. The lower the intensity the less oxygen you’ll consume per minute, but the longer you’ll be able to keep it up.

There’s a whole spectrum of intensity/volume combinations that will produce an equal amount of oxygen consumption (and therefore calorie burn).

What works best for any individual will to an extent be dictated by fitness levels. Most people are capable of doing HIIT simply because your maximum effort is enough to get you gasping for oxygen - it doesn’t matter how unfit you are. Most of the population probably aren’t fit enough to run hard for an extended period of time - most untrained people will not tolerate the discomfort and will drop to an easy pace (which won’t burn many calories).

Simple rule of thumb - if you don’t desperately want to stop you aren’t burning many calories (whether that’s on a longer steady run/cycle or short intervals). There is no painless way to burn high numbers of calories. You need to be gasping for air or else there isn’t much happening.

A definite benefit of intervals is that they’re easier to do. So for example, consider the beginner running that’s only able to jog for 2 minutes then needs to walk for three. That’s intervals!!! As they get fitter they’ll find it easy to run for 30 minutes solid. If they don’t keep pushing the intensity up they’ll burn fewer and fewer calories as they get more efficient at running. However, if they aim to always run that half hour (or hour) at maximum effort they’ll keep burning high numbers of calories.

BUT runners tend to do some of their runs as intervals rather than these hard steady paced runs. Partly because they’re easier to recover from. Even intervals take their toll though - which is why some people resort to longer, easy runs to burn some extra calories without tearing the body down and detracting from other training goals.

The idea that aerobic training is useless for fat burn is nonsense. A flat out 30 minute run is something like 90+ % aerobic. Yet it’ll have your lungs bursting and calorie burn through the roof.

Very intense intervals such as hill sprints probably have other benefits - increase in growth hormone for example. But studies apparently show that even this doesn’t result in greater oxygen consumption. Which suggests it doesn’t burn more fat (contrary to what I and I think most others thought). All sorts of things could be happening. Not least, changes in eating habits. Some studies show that with most people high intensity training reduces appetite. People eat less without realising it.

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“Not least, changes in eating habits. Some studies show that with most people high intensity training reduces appetite”

I didn’t read any of the studies, but did they (I hope) control for calories in? I can do a 10K on a Sunday morning and meet my friends for beer and burgers immediately afterwards. After any type of high intensity exercise, my appetite is shot for hours afterwards.

Having done a ton of low intensity and high intensity work, I always assumed it came down to the appetite-suppressant effects of the type of training chosen.