GI and GL or the ups & downs of blood sugar
A couple of weeks ago I wrote about Glycemic Index (GI).
Since then, I have had several conversations about GI (and glycemic load – GL – of which more later) and how important the release rate of carbohydrates is.
It appears that the ups and downs of blood sugar, and the effect on behaviour, mood and generally how you feel and function is generally not very well understood.
Carbohydrates are an important source of fuel for the body
The trick is to keep supply even!
Too much fast releasing carbs (simple sugars such as fruit + corn syrup found in sweets, fizzy drinks, biscuits, cake, white toast + jam, honey, sweetened cereals, white and brown sugar) and you get the sugar “overdose” scenario.
The body responds to a glucose hit by releasing insulin from the pancreas into the blood. The insulin brings the glucose to the cells where it’s used for energy. Any excess is stored as glycogen in other parts of the body. When the stores are “full” any remaining glycogen is converted to body fat.
A diet high in sugar is probably the biggest cause of obesity.
In a glucose “overdose” scenario, so where lots of simple sugars are consumed in a short period of time (big bowl of processed, sweetened cereals, bag of sweets in the car) the body releases more insulin than usual and too much glucose can be escorted out of the bloodstream.
This leaves you with a blood sugar level that’s too low, causing you to experience a crash in energy and leaving you to want more of what caused the problem in the first place – sugar! – just to feel good …
and round you go again!
It’s a vicious circle that leads to constant cravings, poor concentration, irritability and flagging energy levels.
Carbs that keep blood sugar even
Now that you understand the importance of the release rate of carbs you need to know which carbs are fast and slow releasing.
As a rule of thumb you can assume that unprocessed foods release sugar slowly. For more finesse, you can refer to a measure called glycemic load (GL).
The glycemic load (GL) is a relatively new way to assess the impact of carbohydrate consumption that takes the glycemic index into account, but gives a fuller picture than does glycemic index alone.
If you are already familiar with glycemic index than think of GL as a the more sophisticated sibling.
GI tells you how fast (or slow) the sugar in the food you eat is released.
GL tells you not only about speed but also how much of the sugar there is in the food.
In other words: GI says nothing about quantity. GI of a portion of grapes is the same as a bunch of grapes, whereas GL relates to the serving size.
So you can see the type of sugar effect you are getting from a serving of a particular food.
A good,often used, example of the difference between GI and GL is watermelon.
Watermelon is high GI because it contains fast releasing sugar. However, watermelon contains so little sugar that eating a slice of watermelon actually has little effect on your blood sugar. So, watermelon is classified as low GL.
High or low GL?
A GL of 20 or more is high, a GL of 11 to 19 inclusive is medium, and a GL of 10 or less is low.
For a comprehensive list of the GL of common (American!) foods check this list from The American Journal of Clinical Nutrition
Surprises and suggestions for swaps
Some of the foods you may have thought were nutritious may be surprisingly high GL; luckily, it’s easy to find delicious substitutes that will help keep you blood sugar levels on an even keel.
Here are some examples:
white toast + jam – wholegrain/multi-seed toast + peanut butter or baked beans or a boiled egg
white bagel – wheat tortilla
cornflakes – porridge with a topping of grated apple + cinnamon
croissants + baguettes – rye and sourdough breads
white rice – wholegrain rice
rice cakes – oat cakes
pretzels – salted popcorn
banana – banana + a few Brazil nuts or almonds
Kissing sugar goodbye!
Weaning yourself off sugar is a huge part of the switch to eating for good blood sugar balance.
The best way to do this is to gradually decrease the sugar content of your diet so that you’ll get used to less sweetness. Stay away from sugar substitutes: they’ve been linked to adverse effects on your health and don’t help you to adjust to less sweet food either. The exception is xylitol which is derived from a natural source and has a small effect on bloodsugar levels.
Reserve it for treats or when sweetness is essential, for example in a dessert or cake!
Also, the more fibre and protein you include in your diet, the slower the release of the carbohydrates.
Other habits that affect bloodsugar include coffee (and to a lesser extent) tea, eating breakfast, Coca Cola and other fizzy drinks and chocolate.
In summary, here are my savvy food rules for good bloodsugar balance:
- choose unprocessed foods: wholegrains, beans, nuts, seeds, fresh fruit + veg
- choose wholegrains, avoid refined “white” foods: rice, rye, oats, quinoa, bulghur wheat in breads and cereals. It makes a quick + easy supper, but don’t overdo the pasta.
- avoid sugar + foods containing sugar and all the “-oses”: dextrose, maltose, sucrose …
- combine carbs with proteins + eat fibre rich foods
- eat a good breakfast!
Understanding, and being able to manage, blood sugar is important for health and you’ll soon reap the benefits of incorporating knowledge of GL in your daily diet.
I hope you find the info helpful: do let me have your comments + thoughts.