Skip to main content

The Globe and Mail

Even 'good' foods can disrupt blood-sugar levels

Robyn Mackenzie/Thinkstock

Most middle-aged Canadians pay little attention as their blood sugar levels spike and dip throughout the day, often leading to difficulties maintaining concentration and even causing irritability as their moods swing.

Then there's the infamous mid-afternoon crash when energy levels seem to plummet, making a nap seem like an ideal - although usually inappropriate - option.

But for most people, these aren't mere symptoms of aging. They're often the consequence of eating a diet high in sugary, processed foods, often at irregular intervals throughout the day.

Story continues below advertisement

John, a 60-year-old lawyer from Toronto - who asked that his real name not be used in this article - was guilty of many a nutritional sin when he first visited a dietician two years ago after experiencing dizziness following exercise. His doctor thought the dizziness could be a sign of hypoglycemia, a potentially fatal condition marked by lower-than-normal blood glucose levels.

Living a fast-paced life, the lawyer consumed his fair share of junk food with almost no focus on balancing what he ate and when. "I wasn't on any particularly healthy nutritional path at the time," he explains. "I ate three times a day, but my problem was what I was eating."

He's not alone. As Western diets have gradually included more processed foods and meals have become focused on fast, easy preparation, Canadians have become accustomed to eating the type of foods our bodies simply don't need or have difficulty processing - think French fries, instant rice, cereals, cakes and breads made with enriched white flour.

These dietary trends are not only affecting our mood, concentration and energy levels, they're having a significant impact on our overall health and well-being, while helping to stretch our waistlines each year.

Recent Statistics Canada data shows that one in four Canadians is now considered obese, while six million Canadians are considered pre-diabetic - 50 per cent of whom will eventually develop type 2 diabetes, a condition often brought on by unhealthy nutritional and other lifestyle habits.

With the help of a dietitian, John was able to drop a few kilograms and improve his energy levels by following several widely-accepted tenets of healthy eating: eat whole-grain, unprocessed foods starting with a well-balanced breakfast, followed by two more sensibly-portioned meals with snacks in between.

Those snacks, says Leslie Beck, a Toronto-based dietitian and author of Leslie Beck's Longevity Diet: The Power of Food to Slow Aging and Maintain Optimal Health and Energy, are crucial to maintaining stable glucose levels for improved energy and mood throughout the day.

Story continues below advertisement

"I encourage my clients to eat every three hours to maintain consistent, steady blood-sugar levels," she says.

"That glucose in your bloodstream is your brain's key source of energy. If you're not eating and you let your blood sugar drop, you can feel tired, have headaches and your thinking power isn't going to be as sharp as it should be."

That drop often comes in the form of the infamous mid-afternoon crash - a critical time between lunch and dinner when people become hungry, moody and lose focus, then tend to clamour for snacks to satiate themselves until dinner. All too often, Ms. Beck explains, offices and home cupboards are filled with high-sugar or high-carbohydrate, processed foods, such as doughnuts or crackers.

Not sure how to pick a healthy snack to ease that pre-dinner hunger? Ms. Beck urges her clients to use the glycemic index, a scientific scale from 0-100 that ranks how quickly it takes for a carbohydrate-rich food to cause a person's blood sugar rise. Pure sugar, for example, scores 100 on the scale, followed by all other types of edible food. Low-glycemic foods typically score 50 or less.

Other examples of high-glycemic index foods include rice cakes, cornflakes, baked potatoes, bananas and watermelon. On the low end: peanuts, yogurt, beans, lentils and cherries.

While Canada doesn't require glycemic-index labelling on foods, Jennifer Hill, a dietitian and nutritionist based in Vancouver, explains that adhering to a low-glycemic diet is a matter of reading labels carefully, then portioning meals appropriately and understanding that processing and preparation matters.

Story continues below advertisement

And always keep an eye out for hidden sugars on food labels - those ingredients ending in the letters 'ose,' such as glucose and sucrose.

"Even if you choose low-glycemic foods, if you eat huge portions at a time, it's still going to spike your blood sugar," Ms. Hill explains. "People think if they follow a low glycemic index diet then it's a free for all, but that's not the case."

As she points out, the best foods are those that come in whole form and haven't been overly processed. Take oatmeal, for example. It's a healthy food, right?

Well, yes and no, says Ms. Hill, who points out that heavily-processed instant oatmeal is consumed in small flakes which leaves less work for the digestive tract and leads to sharper spikes in blood sugar levels. Steel-cut oats, on the other hand, come in larger chunks and take longer for the body to break down.

Even whole-wheat flour can have a high glycemic index rating because it's ground into a fine powder - better to buy coarse, stone-ground whole wheat flour instead. As for those mid-morning and mid-afternoon snacks, Ms. Hill recommends healthy choices, such as nuts, yogurt or low-glycemic fruits, such as apples.

At meals, she recommends balancing a plate with a lean protein, such as chicken or fish, a fibrous vegetable -think broccoli or green beans - and ensuring that any high-starch dishes, such as pasta or rice, aren't overcooked, which can make them easier for the body to digest, resulting in blood sugar spikes.

While it may seem like a daunting challenge, John says that managing his blood sugar levels by making healthy nutritional choices was ultimately manageable. As it turns out, he wasn't hypoglycemic as his doctor suspected, but he still decided to maintain a low-glycemic diet to help control his weight and keep his energy levels high.

"It wasn't hard at all, but I think you have to be organized," he says, adding that he records his food consumption in a journal. "You just need a certain level of discipline to be successful."

Special to The Globe and Mail

Report an error
Comments are closed

We have closed comments on this story for legal reasons. For more information on our commenting policies and how our community-based moderation works, please read our Community Guidelines and our Terms and Conditions.