I’ve been counselling people
with diabetes for nearly 15 years and I continue to encounter a lot of confusion
and misinformation about how best to manage diabetes with diet. Concepts like
the glycemic index (GI) are no exception. People are routinely told [and
confused] to eat foods with a lower a GI but what does that practically mean and
is healthy eating as easy as assigning a number to a food?
What is the Gylcemic Index?
Simply put, the GI is a measure (or metric) of a food’s ability [specifically food that contains carbohydrate] to raise blood sugar: in theory, the higher the GI, the greater the impact. The GI of a food is ranked as high [>70], medium [56-69] or low [<55 a="" and="" become="" blood="" br="" carbohydrate="" conditions="" created="" determine="" eaten="" food="" for="" furthered="" gi="" goal="" have="" how="" impact="" in="" it="" level.="" mainstream="" metabolismbut="" my="" never="" of="" opinion="" originally="" our="" person="" purposes="" research="" s="" should="" special="" sugar="" the="" to="" try="" under="" understanding="" was="" where="" would="">
Is healthy
eating as simple as a number?
As a
strategy for healthy eating, diabetes and blood sugar management, many people
with diabetes have been advised to avoid, or limit, foods with a high GI but can
it really be that simple? The GI of parsnips (a nutritious vegetable) has a GI
of 80 – 92 [high] but the GI of table sugar [no nutritional value] is 58
[medium]. Likewise most chocolate bars have a medium GI [56-69]. Using the GI
alone, it’s easy to see how less healthy foods could be chosen over healthier
options and I encounter this in my practice. Clients are almost afraid to eat
carrots, parsnips or potatoes because they think they have too much sugar or
will lead to weight gain but then are confused when they see charts listing ice
cream as a presumably better option give than it has a lower GI. What’s going
on?
Most resources on the GI give overly simplified
examples such as choosing 100% whole grain rye crisps instead of highly refined
rice crackers or soda crackers (Saltines), or 100% whole grain breads instead of
white bread, but also go as far as advising people to stay away from Russet
potatoes, popcorn, Bran flakes, and black bean soup. See here for
examples.
The GI of food, or meal, is affected by
many factors such as the total amount of carbohydrate (or portion sizes),
type(s) of sugar, presence of fat, protein, and fibre to name a few. This is why
a chocolate bar may have a medium GI; the presence of fat, protein, and fibre in
the nuts will slow down the absorption of the carbohydrate from the added sugar
whereas the parsnip is nearly all carbohydrate. The GI fails to take into
account a few key considerations, making its use as a simple guide for blood
sugar control limiting, such as the amount, or portion size, of food eaten, the
quality of the food, whether or not other foods containing factors that affect
the GI are included as outlined above.
I guess it’s
not surprising then that the glycemic index is still being defended and attempts
are still being made to convince people that it makes sense and then persuaded
to use it some 20 years later.
Managing
Diabetes
As an educator I do my best to
deliver direct, easy to understand messages with an appropriate dose of context.
I personally don’t like the GI because in practice I’ve never found it to work
well because of the limitations already mentioned. People eat food and I find it
easier to talk about strategies that are appropriate to an individual’s
situation that help to keep blood sugar levels in a healthy range with tips like
the following.
- ‘Lower & moderate carbohydrate’
diets are not four-lettered words nor bad ideas and are a valid approach to
diabetes management.
- Limit or avoid fruit juice (whole fruit is better
because it has fiber).
- Limit the amount of starch-rich carbohydrate foods
like pasta, rice, bread, buns, bagels, corn, potato, sweet potato, and yes
pulses [chickpeas, lentils, peas & beans]; 60 – 70% of the calories in
pulses come from carbohydrate and although they are rich in protein, they tend
to impact blood sugar like a starch.
- Choose more non/low-starch vegetables
like broccoli, cauliflower, kale, celery, radish, cabbage, asparagus etc. or
those that ‘grow above the ground’ for the most part.
- Include controlled
amounts of fiber-rich foods [100% whole grains, non-starchy vegetables, nuts,
seeds or small amounts of pulses] at each meal.
- Don’t be afraid of fat,
it’s an important source of calories as you reduce carbohydrates. Choose butter,
olive, avocado, macadamia nut, or coconut oil. Don’t overly obsess about
choosing fat-free dairy or extra lean meats. Don’t fret about saturated fats
either, we’ve learned they’re not as bad as we once thought.
- Include a good
portion size [size of a computer mouse] of protein and each meal.
- Avoid
sources of trans fat.
- Increase your intake of omega-3 fats from fish &
seafood. Or supplements if needed [fish, calamari or algae]
- Limit foods
with added sugars [don’t be fooled by ‘natural’ sugars], and refined/processed
fats, especially omega-6 rich grain/seed/vegetable oils [canola, sunflower,
safflower, soy, corn, grapeseed] or margarine, mayonnaise, commercial salad
dressings made with them55>