*It only suited me because I had Insulin Resistance/Metabolic Syndrome/Syndrome-X. I reversed it in 2008. See Insulin Resistance: Solutions to problems for how I did it.
Here's Fig. 2 from Determinants of the variability in respiratory exchange ratio at rest and during exercise in trained athletes. Used with permission.
Respiratory Exchange Ratio (RER) (a.k.a. Respiratory Quotient (RQ)) is the ratio of carbon dioxide breathed out to oxygen breathed in. This ratio depends on the fuels that the body is burning for energy. For example, if the body is burning 100% fats, RER = 0.7. If the body is burning 100% carbohydrates aerobically, RER=1.0. If the body is burning 100% carbohydrates, with some aerobically and some anaerobically (e.g. sprinting flat-out), RER > 1.0. To understand why this is so, see Respiratory Exchange Ratio (RER) explained.
RER varies with intensity of exercise, food intake (increasing protein &/or carbohydrate intake increases it and fasting or reducing protein &/or carbohydrate intake reduces it) and cardiovascular fitness. Increasing cardiovascular fitness reduces RER.
The top diagram is a histogram of fasted RER and % fat oxidation vs. number of subjects. At the left-hand end of the histogram, there are two cyclists with a fat oxidation of 93 - 100%. At the right-hand end of the histogram, there is one cyclist with a fat oxidation of 20 - 27%. Average fat oxidation is ~60%.
As exercise intensity increases, the peak in the histogram shifts to the right as shown in the lower diagram. At 25% of maximum intensity, mean fat oxidation is ~53%. At 50% of maximum intensity, mean fat oxidation is ~37% and at 75% of maximum intensity, mean fat oxidation is ~13%. At maximum intensity, mean fat oxidation is ~0% i.e. 100% of energy is obtained from carbohydrates when sprinting flat-out. Somebody on a very-low-carbohydrate, high fat ketogenic diet e.g. Atkins induction (~20g net carbs/day) could keel over with hypoglycaemia if they exercise for too long at too high an intensity.
As there is variation from person to person, you must find out for yourself your own optimum proportions of proteins, fats & carbohydrates, and these depend upon the intensity & volume of exercise you do. It sounds complicated, but it isn't really.
Apply the principle of "Eat, monitor & adjust accordingly" as Toxic Toffee (ex-Muscletalk member) always used to say. The eating bit will be covered in future Blog posts. The monitoring bit doesn't necessarily involve bathroom scales.
Hang on. Isn't "dieting" all about losing excess weight? Not necessarily. Remember the old joke?
Q. What's the best way to lose 5lbs of ugly flab?
A. Cut off your head.
As your body contains water, muscle, bodyfat, bones, cartilage, tendons, organs, glycogen, skin etc and your scales can't tell the difference between them, losing weight the wrong way can make you less healthy. However, losing weight the right way will make you more healthy.
If you starve, skip breakfast or go for a long run before breakfast, as your body is lacking glycogen reserves & amino acids, a large amount of a corticosteroid hormone called cortisol is secreted, which increases the conversion of muscle into amino acids, then glucose. As muscle has an energy density of ~600kcal/lb, a deficit of 3,500kcal (which would result in a bodyfat loss of 1lb) results in a muscle loss of 5.8lb. For more information, see The Energy Balance Equation.
Chronically-high cortisol also suppresses the immune system and weakens skin & bones.
Unless you have a lot of muscle mass to spare, it's bodyfat that you should be losing, and to monitor this, either use a tape-measure around your waist, check how loose/tight your clothes are, or strip-off and jump up & down in front of a full-length mirror. As Big Les (Muscletalk Moderator) says, "If it jiggles, it's fat.".
2016 EDIT: Scales that can calculate bodyfat % etc are now inexpensive, e.g. Body Analysis Scale.
So, what happens if you eat too much carbohydrate but your body doesn't burn it fast enough? Initially, carbohydrate intake tops-up liver and muscle glycogen stores, which increases carbohydrate-burning to compensate. The liver can store about 70g of glycogen and muscles can store about 400g of glycogen. If, despite increased carbohydrate-burning, more carbohydrate is consumed than is burned, glycogen stores continue to fill. When glycogen stores become full, RER increases to 1.0 and 100% of energy is derived from carbohydrate. Getting 100% of energy from carbohydrate means that zero fat is burned, so keeping glycogen stores filled to the brim by chronically overeating carbohydrate is not a good idea if you want to burn some body-fat.
Once glycogen stores are full, any additional intake of carbohydrate beyond that which is burned passes through the lipogenesis pathway - this basically means that carbs are turned into fat - which may end up as liver fat. But there's even worse news. Fat is secreted by the liver into the blood as triglycerides. This is bad for the cholesterol particles in your blood. See Cholesterol and Coronary Heart Disease. What happens if you eat too few carbs? As stated above, someone exercising at a highish intensity taking in insufficient carbohydrates could get hypoglycaemia & keel over.
How many grams of carbohydrate per day does it take to promote lipogenesis? Someone at rest burns ~1kcal/minute. If this is derived 100% from carbohydrate, this is equivalent to 0.25g of carbohydrate/minute, or 15g of carbohydrate/hour, or 360g of carbohydrate/day. Therefore, sedentary people who chronically consume more than 360g of carbohydrate/day may produce significant triglycerides. People who have The Metabolic Syndrome/Syndrome-X (a high proportion of people who have excess belly fat) have increased lipogenesis and higher serum triglycerides than healthy people.
Discussing weight again for a moment, it's often said that all diets are the same, as weight loss is all about calories. This is true. See Is a Calorie a Calorie? However, body composition is determined by a combination of macro-nutrient proportions (i.e. the relative amounts of proteins, carbohydrates and fats in the diet) and the intensity & volume of exercise. Health is determined by a combination of micro-nutrient proportions (i.e. vitamins, minerals & anutrients) and exercise. See On burning, storing and recomposing.
If you're only interested in weight loss, just count calories. If you wish to lose bodyfat without losing muscle mass, you need to know what proportions of proteins, carbohydrates & fats to eat (it's really not that critical, but many people get it wrong). You need to know the difference between good carbs & bad carbs, and good fats & bad fats. You need to know the best times to eat proteins, carbohydrates & fats relative to exercise (it's also really not that critical, but many people get it wrong). You need to know the difference between good exercise & bad exercise.
Continued on We are not all the same.
17 comments:
You made a profound statement here:
"Everyone is Different. When I first discovered Low-carb Diets (thanks to the late Dr Atkins), I thought that it was the One True Diet, and I became a bit of an "Atkins Diet" bore telling everyone how wonderful it was and suggesting that everyone should be on it. I now know that what suits me doesn't necessarily suit someone else. So why do "Healthy Eating" guidelines assume that everyone is the same and tell everyone to get 15% of their total calories from proteins, 55% from carbohydrates and 30% from fats?"
"Everyone is Different." Yes, indeed! In my opinion, everyone studying to be a doctor, nurse, dietitian, diabetes educator or endocrinologist should start every day by repeating those three simple words.
Unfortunately, much of American health care seems to treat patients as objects on an assembly line, with a one-size-fits-all approach, which is usually expressed something like this:
Take a daily low-dose aspirin, a daily statin, a daily metformin, a daily diuretic, a daily beta-blocker, and come see me again in 6 months for another 5-minute appointment"
Hi Jim.
When I first stumbled across that study on Substrate Utilisation by Julia H. Goedecke et al in the book "The Lore of Running" by Dr Tim Noakes, it opened my eyes as to just how variable people were.
Luckily, Goedecke & the American Physiological Society gave me permission to use Fig 2 in my writings.
Cheers, Nige.
FYI Males, especially ones that are trained, can store ~150g as liver glycogen and ~800g as muscle glycogen.
If you were burning nothing but carbohydrates your metabolism would raise by about 20% as well so you would burn about 1.20 cals per hour.
Hi Nigel,
Quick question regarding RER and cardiovascular fitness.
Do you have any journal links that establish this connection? That is, a good argument that lower RER is a sign of better cardiovascular fitness?
I found Fitness: a new look at an old term (measurements of human aerobic performance).
Many thanks.
With the Ray Peat influence growing on the internet, there are arguments being mounted up in favour of having a high resting heart rate and body temperature, indicative of a glucose oxidative metabolism. I'd say this thinking's kicked up a notch to the extreme, and I'm not even including the lunacy over at Banana World.
Yet, as your post, references, and numerous other fitness articles discuss, the cardiovascular conditioning of an athlete is seen as better with a lower RQ as opposed to a high one. I mean many of us have been through our moments of highs, and while they're exhilarating, they have this 'burn out' element. I believe maximum -- or even largely -- glucose oxidation is something reserved for extreme levels of exertion and stress, and probably not desirable as a general state.
I also broached the subject of substrate utilisation in It's all in a day's work (as measured in Joules) Part 2.
So, more aerobic fitness -> less muscle glycogen utilisation -> more endurance at an exercise intensity where significant glycogen is used (>25% max.)
Conversely, less aerobic fitness -> less bodyfat utilisation at the above exercise intensity.
Thanks again, Nigel. I've actually read that post before. Again, I agree with the findings, it's just that these days, the internet seems to be full of a lot of 'paradigm challenging' mentality, to the point that well-known positive notions are now being deemed negative.
So having considered all these factors, for someone who isn't perpetually running at peak levels all over the place, or someone who is quite active but fit to the point where their body does utilise a substantial level of fats, a very low fat vegan diet might not be a good idea with regards to energy stability and glucose management.
That's a $64,000 question. Unfortunately, I don't know the answer. Fit people appear to be able to eat diets containing a wide range of energy % from carbs and their RERs/RQs go up & down to suit. That said, carbs from roots, tubers, veggies & fruits produce less BG & insulin fluctuations than carbs from grain dust, due to the lower GL of the former compared to the latter.
I believe that vegan diets need to be supplemented with DHA & B12.
A diet containing a high % of veggies & fruits doesn't suit me at all, as it doesn't keep my stomach satisfied for very long and it also makes me fart a lot!
Fair point, although I do know a few people on the high side of the fitness and body leanness spectrum. I am one of them myself. And typically, a very high carb (thus very low fat) diet constantly isn't very optimal in our collective experience.
What I've found is that a high grain, high carb, also high sugar diet, tends to send my heart racing quicker. I somehow find a more gradual and sustained form of energy from the fattier meat foods. I do feel burned out on the former.
As for the GAS issue on vegetables, beans, and roots. Well, that's a whole other world of bane and I have yet to find a legitimate solution short of crazy tactics that make no sense. Makes me wonder how many of these indigenous plant-based cultures thrive so well. The Japanese and others in the far east, tend to rely a lot on easily digestible starches as their staple with the greens and veg as a small side dish, along with equally sparing quantities of meat.
My interest, really, is in long-term health and longevity. I have seen first-hand anecdotes of how hyperglycaemia -- even from cortisol -- can do to a person with regards to accelerating degenerative processes. I know that it's a highly contentious topic in the blog-o-sphere at the moment with the whole, 'which fuel burns cleaner' arguments.
Does boiled rice make your heart race? I think of boiled rice as being a fairly safe starch as the grain is relatively intact and it also has a high water content. Are the sugars in whole fruits a problem?
I don't get much wind from boiled rice, roots & tubers - it's greens, legumes & alliums that are deadly.
I don't fully understand the technicalities of fuel-burning "cleanliness". As the vast majority of energy is stored as body-fat, I would hope that the body manages to burn the stuff without damaging the works.
I think that people should eat enough safe (in terms of how they make you feel & gas production) carbs to fuel their activities. It becomes fairly obvious if carb intake is insufficient for lots of high intensity activity (e.g. running a marathon or doing a very physical job) - you "hit the wall".
As you're fit, you're burning more body-fat & less glycogen at moderate exercise intensities, so you don't need to eat *that* much carb. Carry on doing what you're doing.
Thanks for the response, Nigel. You've come to a similar conclusion that I've arrived at as well.
I should be clear on the heart racing part. It's not abnormally fast or uncomfortable. I used to kick box, and still continue my warm-up routine as it's something I like doing. What I found was that on a lower carb diet, I could meet a certain performance level at a certain pulse rate. In the case of high carbohydrate and sugar, the pulse rate would be significantly higher at a similar performance level. It didn't feel uncomfortable, but it did feel like inefficient utilisation of energy.
Clean burning. Yeah. I'm puzzled by some of the arguments. Here's the thing though, I am sure you've read up plenty on De Novo Lipogenesis, and how insignificant a pathway it is touted to be by some, even in large overfeeding scenarios. So on one of these vegan diets that are completely purged of any overt fats, I would assume that in a hypercaloric state, the body would be under pressure to oxidise most of the glucose if it can't go anywhere else, which always poses the risk for lingering around too long in the blood stream. Otherwise, De Novo Lipogenesis might not be so insignificant as it is made out to be even in modest overfeeding scenarios.
There's something I noticed among McDougall dieters looking to stabilise their blood sugars; quite a few seemed mildly hyperglycaemic, and the others who weren't, were generally in active caloric restriction, even to extreme levels. Seems like many of these cultures that do observe a very high starch diet, tend to observe an active agricultural life style working the fields where they're practically living in a state of glycogen depletion through perpetual activity. This is why I don't think such a dietary protocol would yield optimal results when applied to a modern, western life style, even with healthy-to-intense, but short bouts of exercise.
Anyway, I am doing an experiment. I want to see how the body responds to the whole experience of very low fat veganism, especially since I now have a glucose meter. So I am going to continue this starch-based (rice and potatoes as base; lentils and vegetables as side) vegan diet for a few more weeks. As it stands, I am supplementing daily with B12, Vitamin D, and ground flaxseed, because such a pattern of eating does bring about crucial deficiencies in the above-mentioned micro nutrients, which as you know, have other far-reaching consequences that can muddy the end result.
RE DNL: The study Glycogen storage capacity and de novo lipogenesis during massive carbohydrate overfeeding in man suggests that DNL can generate ~150g lipid/day when disposing of ~475g of unstoreable & unburnable carb/day. That's not insignificant.
Good luck with your vegan experiment. I'm not sure that getting omega-3 from flaxseeds only is good for the male brain, long-term. See Linseeds/Flaxseeds & Flaxseed oil. A few weeks won't hurt.
Well, good day to you Mr. Kinbrum. I trust that all's well at your end!
I've been a bit off the grid. Or rather, fighting on other turfs. ;)
However, I have read that paper you linked. It was passed my way by another contact who's interested in the subject since people over at Banana Land (30BAD) were harping on about it, and even using it to explain that weight gain CAN happen. I was bothered a bit by the paper, because it looked familiar, and then I remembered having saved a copy of it on my old computer many bloody moons ago -- no joke! Wow. It's funny how old stuff floating around becomes relevant again in the heat of revitalised debate on the topic.
I have done my experiment, and have reports that somewhat agree with this study. Generally, my results are good, but I will tell you something. Even a fit body starts to rebel against certain conditions eventually if it is not happy taking them on for the long haul.
My criticism of this study is sparse. Given the financial climate around this topic, I know that this probably the closest we'll get to decent human studies. Now it generally seems fine, but it deals with a small number. The individuals are also quite fit. Also, it didn't run the kind of duration that would allow us to critically examine long-term effects of such a scenario. Would their RER eventually suffer or fire back on them?
In my brief experience/experiment, fasting glucose improved, and postprandial response was also great. No gain in weight, but. . . I've always been that way. In fact, I've dropped a bit from my relatively emaciated physique, and I am sure some of that's muscle since fat is sparse.
I did find that the glucose response, which I measured very carefully and regularly -- randing from from 1/2 hour reads, all the way to 3 hour reads -- was stable. This did start to worsen a bit after the 4 week mark. Nothing drastic or worrying, but given that I rarely ever exceed 5.5 mmol/l (99 mg/dl) in postprandial state, some higher reads did take place. In this case, I was hitting a few 5.8s and perhaps a single 6.0. No big deal, but those higher reads did become progressively frequent around week 5, with the 6.0 mmol/l coming two days shy of ending the experiment.
After ending this trial, I switched to a meatier diet where carbohydrate was substantially lower. In this case, I only consumed carbohydrate in relative need of how much of a physically intense day I would have. So I was primarily consuming meat with some vegetables on the side, and some tubers here and there. The reads were always stable, and lower in general. Fasting stayed at around 5.0 for physiological reasons, while post-meal reads tended to drop into the 4.5-4.8 mmol/l range after which my mid-day fasting levels would remain at around 4.4 mmol/l. Overall, it comes off as a much straighter line on a graph throughout the day, even when taking 4 and 5 hour reads at regular intervals and comparing them to 1/2 and 1 hour reads.
Of course, this is my own finding, and my personal experiment. I am sure there'll be drastic variation. Everyone's different, right? Heh.
Oh. And the flaxseed stuff.
I did start supplementing mid-way with fish-oil instead. It didn't matter since this is trace fat that we're talking about, and I had a whole bottle. So I had to make economies and decided to put this bottle to use. Nothing to report there, either. All seemed good in the upper faculty department. Although I am sure that we can all agree -- too short a time! I've seen people torture themselves on worse regimens and make it a whole year while being as cerebrally sharp and annoying in arguments as they've ever been in their prime.
Well, hello Mr Storm. Let's just say that things here have been better, which is why I haven't been blogging recently.
So, a diet of meat & veg that's moderate in carbs gives you lower & more stable BGs than a vegan one that's high in carbs.
I have no idea what caused the gradual worsening of your pp BG on the vegan diet.
I am sorry to hear that, Nigel. I hope whatever it is, it isn't too serious and something that can be managed. Your entries have most certainly been missed.
Yeah, so meat and vegetables -- moderate carb -- gave a stable line. I guess that shouldn't come across as a surprise.
I do have some theories as to why there was the occasional -- relatively speaking -- spike on the vegan approach. In my case, I believe cortisol would've play a part. I've had this (cortisol increase) happen before on various approaches. Usually follows when life's a bit hard on the physical front. As I mentioned, Although I can never be certain. I did drop some weight and I am sure quite a bit of that was muscle, so thar we go!
On the whole though, the reads were far from bad. I just took interest in the subject and decided to give it a shot because my contact found that over on the McDougall forums, many individuals were testing higher on A1C and showing hyperglycaemic (by our alternative/ancestral/whatever standards) reads. Also, the few that had low reads were calorie restricted, quite substantially in certain cases.
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