What do you think of my thoughts on metabolism, blood sugar, and diet?

Question

Hear me out on this. Yeah if you know the stuff I post you know this is going to get long. Settle in.

I'd like this question answered seriously by serious people. It's my intention to one day write a fitness self-help book. I'd like to know what I'm talking about, not just for the sake of being informed, but because I'd be giving advice to be people from which they'd be making decisions on their lives. Naturally I feel a responsibility. I suppose one could argue that this is not the place one should form their ideas for that sort of thing; and yet one can't argue that this is a place that forms ideas, and, more specifically, ideas of mine will be formed here, regardless.

Ugh. The luck I've been having I asked this question in Diseses & Conditions>Diabetes (I'm like, hey, these guys no about blood sugar and such). I guess I should have posted it at an earlier time of day because my lone response was a guy spamming weight-loss berries from Oprah (no really). I posted it on Diet & Fitness, and it didn't even show up on the Diet & Fitness page! (Apparently that's been happening with Y!A lately. That and I think my long question broke it.), and then it happened again. So anyways, fourth time the charm?

The thinking on the glycemic index these days is that a high post-ingestion blood sugar spike is a bad thing, because the parts of one's metabolism that convert metabolisables into body fat work hardest when there's an abundance to work with. The reason being that in evolutionary terms the best way these nutrients can be kept is deposited as fat, not swirling around in the blood stream, which can't maintain anywhere near as high an energy density (duh) especially since excessive blood sugars have toxicity issues and must be excreted from the body. Basically the body is rushing to convert this stuff to fat while there's still a bunch of it before it all gets flushed out.

I have the notion there's more to this story though. Nutritionists talk about how low glycemic foods, give you much more energy down the line than high glycemic foods of equal calories, because, for whatever reason, the blood sugar profile of these foods is less a graph with a high spike and a rapid descent into low blood sugar, and more a low spike followed by a very shallow drop over time of moderate blood sugar, which keeps you feeling energetic and full of spunk.

Most metabolisable nutrients have been given the O.K. in this regards. Proteins, fats, complex carbohydrates may not be equals, but are at least far better for you than simple sugars.

Now there are some things that really bother me about that. What's going on is we are given two values, the Glycemic Index, and the number of calories in food, and that's supposed to tell us everything.

Just to give an example if you have a high glycemic index food with a certain amount of calories, then you know two things. You know your blood sugar is probably going to be real high after you eat that food and you know the potential metabolisable energy that your body can extract from that food.

Well suppose you want to make a graph of what that would do to your blood sugar over time. What you have is the peak value of that graph and the area that should be under the graph's line.

You know what? That leaves alot undefined. You could have high blood sugar plateaued for a short time that then crashes like nobody's business. You could have an immediate steep decline in blood sugar. Or, you could have a quick drop in blood sugar, with moderately elevated blood sugar for some time after. You really don't know.

This problem is helped even less since there's alot we don't know about these values that we're supposed to know. The Glycemic Index is not a measure of the immediate effect on blood sugar by each metabolisable nutrient in each category. It is not produced by calculations based on the chemical characteristics of fructose, or Omega-3 fatty acids. It is an empirical measurement of the effect of specific FOODS, that contain a variety of metabolisables, on blood sugar. In a way it is a composite measurement of the combined effects of every nutrient, and even the physical makeup and texture of a given food. And as I've suggested, nutritionists would help us out alot to try and track the effects of foods on the blood sugar over time.

Of course, there's reasons why that's easier said than done, and perhaps even less scientific than what we're talking about in the first place. The lasting effect of foods is sometimes lost in the background (or more than background) noise of people's fat's contributions to their blood sugar. And such data over time would require fasting, before and for the duration of the tests.

And we don't know calories the way we think either. Maybe you already know that there is not a one to one to one relationship between the number of calories that we chew and swallow, the number of calories that end up as blood sugar, and the number of calories that end up as body fat. Not everything that goes into your mouth is destined to go on your hips. But, did you know it's not just because your body isn't set to turn everything it gets into body fat, and it's not just because of the Glycemic Index?

What we're dealing with is a theoretical number. In theory, if your body put some real effort into it, it could pry every calorie loose from that granola bar. But, I don't think it will come even close to doing that.

So what, you ask? After all that just means even less calories to worry about than you thought. O.K. Let's go back to the whole nutritionists say low glycemic index foods are good because they make you have more personal energy to take you through your day thing. You say, so I'm down on energy, that'll just encourage my body to burn some fat instead. I may feel down, but I'll feel better when I'm fit.

Besides that I'm fairly certain that I've seen studies that say that starving your body whatever way you do it is not a sound strategy for lasting fitness, I still have to think that's flawed. You have to take this in the context of what that means for the parts of your body that regulate your body fat. From that perspective if blood sugars are always low that's all the more reason to convert metabolisables into fat when there's a spike in them. Whenever that spike may be.

To my thinking, for obesity the problem here is not high, medium, or low blood sugar levels. It's the jumping up and down, and the steep rises and falls of the blood sugar levels.

Even complex carbohydrates could be bad to this line of thinking. Sure they might not spike your blood sugar very much, but what then? How long does that last? And, how steep is the crash?

That's really what largely got me thinking on these ideas in the first place. Complex carbohydrates have been lauded for how they have low glycemic index, because it's hard for the body to convert them from food to blood sugar. My reaction to that was, that doesn't mean complex carb's are good for you because they have a low glycemic index due to their low impact on blood sugar. That means complex carb's have next to no effect on blood sugar ever so their low glycemic index is worthless. They'ra just another kind of a starvation diet.

And, my hunch is that since complex carbohydrates are cut from the same cloth as simple sugars they are suspect. I mean there are lots of dieticians, especially sports dieticians, who will tell you that carbohydrates are still an important part of your diet.

My point is they're not an essential part of your diet. You can't live without proteins, or fats. You can live without carb's. The closest thing they're is to a nutrient carbohydate is dietary fiber (certain kinds of complex carb's), and even they're not essential, even though yes you should include them in some way, especially if you're trying to get your cholesterol levels under control.

But, I suppose given the information we really have we can't any more certainly point the finger at complex carbohydrates, proteins, or fats. (But simple sugars? Oh yeah.)

Answer 1

I think your question(s?) is typical american diet propaganda. Its that looking for a magic formula principle or applying science in someway to allow us have our cake and eat it.

I'll tell you why I think American diets don't work really- your society is based around the car ; drive everywhere;people are in wall mart driving around the aisles in motorised trolleys..I even remember seeing healthy but fat kids being pushed in wheelchairs by their skinny parents in between rides in Disneyland. You don't actually use an awful lot of glucose or glycogen stores because each year you find a way of moving less and less as a nation so that if you decrease your glucose intake it probably isn't noticed. When we try your GI diets etc we often faint cos the level of glucose is too small for our more active lifestyles.The truth is any fad diet willwork because you fatigue of eating the same c**p day after day and you lose your interest in food and eat less without realising it

My guess is the obeisity epidemic is a result of food science and is solvable by laws limiting saturated fat content and sugar content in food that was developed for pre WWII people who were on the verge of starvation and to whom a fat enriched diet was a lifesaver back then. Throughout history all countires have faced famine : thats why the english sent Sir Walter Rayleigh off to find potatoes , a source of carbohydrate. Nowadays we simply enrich our food...I seem to remember nearly everything you'd eat in the USA was sugar coated like the way you'd feed frosties to a kid who wouldn't eat..except this was adult food ! The obvious way to reduce fat is to produce foods lower in calories, fat and carbohydrates by law. Its soooo obvious but no one does it.

To answer your stuff about intermediary metabolism your talk about the graph of glucose levels versus time is interesting. The area under the curve is called the bioavailability ( absorption) of glucose as released from the foodsource. However glucose is a complex creature because its blood levels are influenced by insulin, adrenaline, glucagon, glycogen formation, the Km of enzymes such as hexokinase and glucokinase. Right enough a peak of glucose stimulates insulin release causing the conversion to fats and glycogen (immediate stores) and glycolysis...conversion to pyruvate in order to enter the Krebbs cycle in the mitochondria. Some people probably have more/better mitochondria than others and this might contribute to weight diffences.The basic evolutionary force you speak of is really survival of the fittest at maintaining blood glucose above 5 mmol in order to keep the brain from dying ( can only burn glucose) . Hexokinase, the entry enzyme of the liver where metabolism largely occurs, has a Km of 5mmol...this means as blood glucose falls below 5 mmol its intake of glucose falls to virtually zero.This conserves glucose for the brain. Similarly starvation, through release of growth hormone causes initially the consumption of protein ( heart muscle mainly) initially and finally the mobilisation of fat stores ( glycerol ->glucose, fatty acids to ketones which are usable by Krebbs cycle if L-Carnithine is present to transport in the fats) after about 3 days. We know an awful lot about this process of starvation mainly from hospitalised patients. The shock to the body of an operation often causes large amounts of adrenaline(epinephrine) and cortisol release that promotes internal catabolism of protein and to a lesser extent fat stores. Initially it may be possible to directly supply glucose via an intravenous drip but usually after a few days in order to prevent loss of heart muscle you need to supply a certain percentage of the calories as protein and fat ..I think roughly 30/30/40 ( fat/protein/glucose) in order to stop the loss of heart muscle from the metabolic shock. Its the same with diets...you do need a balanced diet in order to prevent the body thinking it needs to produce one food group to suppliment its lack of another foodgroup( fat/protein)  and to maintain glucose levels. Yes, I concede the glycemic index is probably a good idea in the sense it promotes foods with a slow release profile for glucose and sustains blood levels of glucose more evenly ( your curve is more elongated and the peak is broader) but overall you need to reduce calories modestly across all 3 foodgroups and increase exercise to preserve muscle protein.

There is more. I lost 3 stone once in Weight watchers. My success , I perceived was down to the ability to estimate food more accurately in terms of their points system ( calories vs saturated fats) and the fact I weighed my food. It was extremely hard the first few weeks until I lost my stomach fat and after that it was easy. I formed the impression my fat cells in someway signalled my satiety centre but after you lost this fat store the signal strenght weakened ( less output from fat). I understand leptins actually do this , it was subsequently discovered and antileptin drugs may ultimately be the cure. Keeping off the weight was harder because, in my opinion, most foods you buy are artificially enriched with calories, sugars and fats and your basic western meal is enough calories for a whole day. I think governments limiting fats in foods is the only sane diet solution :)