GI is a ranking of foods based on their overall effect on blood glucose levels. Slowly absorbed foods have a low GI rating, whilst foods that are more quickly absorbed will have a higher rating. Its a Daily Express and Daily Mail favorite, how do I know? Well my Mum buys the Express and frequently saves me articles she thinks I'll like, I personally think she brings the ones that will have me banging my head against the wall.
The GI view on diabetes kind of misses the point though, our bodies are a tad more complicated than GI takes into account. We have many hormones to regulate our blood sugar and its important to take that into account. Assuming that your blood sugar is out of balance because you ate some sugar and you aren't producing insulin is a one sided view of it. Most people recieive a glucose tolerance test and from this it is deduced that your diabetic.
Insulin is responsible for blood sugar going down and cortisol (yes the very same cortisol I'm always banging on about folks) does the opposite and sends blood sugar up. So the two work as opposites to function exactly as we need them to. Carbohydrates (Glucose in particular), raises insulin and lowers cortisol. Yep thats it folk nasty old sugar has some gooooood effects. Lets clarify that, insulin takes blood sugar down and glucose causes insulin to work. Cortisol raises blood sugar and is lowered by glucose. So how can sugar be the cause of diabetes? An how can low carb, low GI etc be the answer that we need? Clearly diabetes is a bigger story than some would have us believe.
Cortisol has the effect of raising blood sugar levels due to it being one of our stress hormones, and in times of stress we need to mobilize sugar. If glycogen stores are low (such as on a low GI, low carb or just plain low calorie diet) we get that sugar from the breakdown of our own tissue. Remember it could be an emergency response so your body happily sacrifices some tissue to aide survival.
So cortisol and adrenalin (along with a few other things for another post) are the more likely candidates for blood sugar problems. When glycogen stores are depleted, often the end result is catabolism in which tissue protein is broken down to provide amino acids, which in turn provides us with fat and sugar for use as energy. Not our bodies optimal way of sourcing energy, but if we insist on using less carbohydrates or slower releasing sugars then we have to have a mechanism of surviving.
The simple fact is we are designed to function with sugar, its our bodies preferred energy source. Any attempt to slow down sugar absorption is simply attempting to cut corners and not look at the actual problems occurring in individuals diagnosed with "debatable diabetes."
Ray Peat has a fantastic quote in one of his articles, 'The degenerative diseases that are associated with hyperglycemia and commonly called diabetes, are only indirectly related to insulin, and as an approach to understanding or treating diabetes, the “glycemic index” of foods is useless. Physiologically, it has no constructive use, and very little meaning.'
As Peat points out, 'glucagon, cortisol, adrenalin, growth hormone and thyroid tend to increase the blood sugar, but it is common to interpret hyperglycemia as "diabetes," without measuring any of these factors.' People are regularly diagnosed with diabetes and told they aren't producing insulin without their insulin function ever being tested. Maybe your one of them? Time to start asking your diabetic nurse some questions I think.
Avoiding carbohydrates, eating slow releasing carbohydrates or low GI often causes low blood sugar (don't forget low blood sugar is just as bad), which causes the above mentioned release of adrenalin and cortisol to raise blood sugar back up. If the liver has no glycogen left then it becomes cortisol job to break down tissue to produce energy. So, via trying to avoid giving the body what it wants (i.e its proper energy source) adrenaline, and cortisol (plus something else which is for another post) cause insulin resistance.
As Peat points out 'In the 1970s, dietitians began talking about the value of including "complex carbohydrates" in the diet. Many dietitians (all but one of the Registered Dietitians that I knew of) claimed that starches were more slowly absorbed than sugars, and so should be less disruptive to the blood sugar and insulin levels. People were told to eat whole grains and legumes, and to avoid fruit juices'.
Its still going on today, from university courses (remember why I dropped out of an MSc in Dietetics before they even got the chance to brainwash me).
David Jenkins (1981), proved starch to be 'higher glycemic' than sucrose as did Houssay (1947 Nobel laureate). Yet both are largely ignored in favor of pharmaceutical and diet industry profit. The nurses, nutritionists, PT's and doctors you see aren't lying to you. Its just what they've been taught to tell you. At most they're guilty of believing everything they got taught. Its quite similar to the way religious beliefs continue...someone tells you their beliefs and you just follow their word.
I've stated it so many times before so its nice to see someone as academic as Peat agreeing that; 'Eating "complex carbohydrates,” rather than sugars, is a reasonable way to promote obesity. Eating starch, by increasing insulin and lowering the blood sugar, stimulates the appetite, causing a person to eat more, so the effect on fat production becomes much larger than when equal amounts of sugar and starch are eaten. The obesity itself then becomes an additional physiological factor; the fat cells create something analogous to an inflammatory state. There isn't anything wrong with a high carbohydrate diet, and even a high starch diet isn't necessarily incompatible with good health, but when better foods are available they should be used instead of starches. For example, fruits have many advantages over grains, besides the difference between sugar and starch. Bread and pasta consumption are strongly associated with the occurrence of diabetes, fruit consumption has a strong inverse association.'
Yet more evidence to avoid grain like the plague. The most interesting facts that Peat point out though are the facts that when the pituitary gland (the master endocrine gland) and the pancreas are removed, that the resulting lack of insulin doesn't cause hyperglycemia. An increase in cortisol helps to maintain normal blood sugar. It appears that when the thymus gland is damaged by stress, cortisol or the dreaded polyunsaturated fatty acids (pufas), the thymus cells have greater sensitivity to cortisol. Sugar on the other hand has the opposite effect and protects the thymus from cortisol. Pufas are rife in society nowadays, from vegetable oils, seed oils, many vegetables, through to the grain recommended on typical GI plan.
Polyunsaturated fatty acids activate stress hormones, and if its used sugar contols the damage. Take a typical so called "healthy" meal, chicken breast cooked wish a little sunflower oil, wholegrain pasta and a plate full of vegetables and you have yourself a mass of pufa with no sugar to counteract the damage. You can swap this meal for any of the typical "healthy" meals I see suggested by many health professionals who've done nothing more complicated than tell what they were taught to tell you.
I'm not suggesting you all go out and start ingesting tate and lyle like its going out of fashion. In the first instance eradicate as much pufa as possible, start with the really bad stuff like vegetable oils, grain oils and cut out as much (if not all) grain from your diet. Then as your ready to progress, start looking through other sources of them.
Equally don't focus your efforts on low GI or low carb. Your cells need the correct energy so don't try and give them sources which release slowly and also increase your susceptibility to insulin resistance.
Understanding that sugar isn't the enemy is a big step for most so don't take any rash steps that your not yet happy with. Begin by looking at if low GI or whatever bizarre diet your on is actually working for you or anyone.