There is lots of contention with regards to carbs these days and a lot of demonizing of this amazing and important macronutrient. With the prevalence of low carb diets there is a lot of misinformation being spread about carbohydrates and their effects on the body. From the narrative of “carbs make you fat” to the fear mongering about blood sugar spikes, it's no wonder why so many people fear consuming these foods. Let’s do a deep dive into carbohydrates and hopefully dispel some of the fear surrounding them!
There are 3 major macronutrients that make up our diets: carbohydrates, proteins, and fats.
Protein and fats are what are called “essential macronutrients” because we must consume some form of them through our diets as our bodies cannot survive without them. Carbohydrates on the other hand are a “non-essential macronutrient” meaning we can survive without consuming them through our diets. Though this is true, the brain, the nervous system and red blood cells require glucose to function. What's amazing, is that in the absence of dietary carbohydrates our bodies can make glucose from the proteins we consume as well as
lactic acid produced from exercise through a process called “gluconeogenesis”. How cool is that?
It is important to note that just because we don’t need them doesn’t mean that not consuming them is optimal. Carbs provide our bodies with the fuel needed to perform high intensity anaerobic exercise like sprinting, biking, swimming, weightlifting etc. Though it is absolutely possible to thrive on a low carb diet, certain forms of exercise may be more challenging, and fatigue may come sooner. Following a low carb diet or ketogenic diet is highly individual and some have great success, but the lack of this macronutrient may affect performance.
Digestion
To understand the digestion process for carbohydrates it will be helpful to look at the differences between the various sources of this macronutrient. Carbs can be split into two sorts of categories either “simple” or “complex”. Simple carbohydrates are things like white sugar, honey, maple syrup, corn syrup etc. These are generally lower in nutrients and are released into the blood stream very quickly after consumption as less digestion and processing is required. Complex carbs will generally contain fibre and a wider range of nutrients and will be released into the blood stream more slowly as they take more time to digest. Some examples of complex carbohydrates are starches, vegetables, grains, fruits, beans.
Once consumed all carbohydrates are broken down from more complex forms into more simple forms through the digestion process. They are then absorbed through the intestinal wall and sent to the liver where they are converted into glucose. It is important to note here that all dietary carbohydrates no matter
the source are eventually converted to glucose. Glucose is then released into the blood stream (blood sugar) and the pancreas responds by releasing insulin whose job it is to lower our blood sugar levels by removing it from the blood stream and “putting” it into the various cells that need it thus lowering our blood sugar levels. Glucose can also be stored in our muscle or liver cells in the form of glycogen for later use. What is pretty amazing is the body can store approximately 300-400 g of glycogen in our muscles and about 100 g of glycogen in our liver which is quite a bit of stored energy! Glycogen is like an energy reserve and our bodies can convert it back to glucose to be used as energy when needed.
Carbohydrates and Weight Gain
There is an old narrative that carbohydrates and specifically the insulin released after the consumption of carbs is the reason for fat gain and obesity. Insulin is demonized and blamed for the obesity epidemic, using it as a scapegoat for the rise in obesity rates. A lot of this data is correlational and mechanistic, and studies do not support this. Actually, when we look at studies that compare low carb diets vs high carb diets, we see that the results as it relates to weight loss is pretty much the same
When this model is examined further, we see that there are many holes in it. We do not see more body fat loss or weight loss for those who follow low carb diets and the data does not appear to support that low insulin promotes more overall body fat loss. It is true that sugar is highly palatable, and desserts can be easy to over consume but the same can be said with high fat foods. Many of the processed foods that we think of as high carb foods actually contain more calories from fat than from carbs so its hard to blame all of this on carbohydrates.
Blood Sugar
What many people think about when insulin is discussed is diabetes and insulin resistance (pre-diabetes). There are two types of diabetes, type I and type II which unmanaged can lead to several negative outcomes.
Diabetes type I occurs when the cells of the pancreas are not able to produce insulin and thus unable to lower blood sugar. This type of diabetes is genetic being generally discovered early in life and requires lifelong insulin support. Pre-diabetes or insulin resistance is when the cells become desensitized to the insulin released leaving blood sugar higher. In more severe cases and left unchecked this can lead to the cells becoming unresponsive to insulin all together which is called type II diabetes. This type of diabetes is
mainly lifestyle related and develops over a period of time, but it can generally be reversed with lifestyle and dietary interventions. Risk factors for this condition is obesity (especially abdominal obesity), smoking, family history, high blood pressure and high cholesterol.
With simple carbs we will get a higher spike in blood sugar as these are processed more quickly. Complex carbs will result in smaller spike with a steadier release of blood sugar. For those who have diabetes low carb diets can be useful, but these are not the only option. Consuming these complex carbs that contain higher in fibre, consuming protein with carbs and consuming some fat with carbs can slow the release of blood sugar and keep it more steady. Another major way to minimize risk will also be to lose weight as this can help to reverse certain blood markers related to type II diabetes as well. Unless you fall under the category of pre-diabetes or diabetes there is no reason to micromanage your blood sugar.
RISES IN BLOOD SUGAR ARE NORMAL IN RESPONSE TO EATING CARBS! Consistently high levels of blood sugar can have negative impacts but unless you have a condition you do not need to fear these fluctuations.
As with all my other nutrition advice there are no “good” or “bad” carbs and even your favourite
sweets can be incorporated into a healthy diet. My advice would be to stick to mainly complex carbs while including some of your favourite simple sugars in moderation as well.
Some Takeaway Items
- Consume most of your carbohydrates from complex sources. This will help to keep blood sugar
levels steady and will help add to your daily fibre intake.
- Do not fear simple carbohydrates and sugars. You can absolutely incorporate these into your
diet in moderation. These carb sources can be great for long bouts of exercise and can provide
you with that much needed energy to help you complete your workout.
- Insulin and carbs do not appear to be the cause of obesity. A calories deficit no matter how
you achieve it will be the determining factor when it relates to weight loss.
- Weight loss can improve insulin sensitivity and can help reverse type II diabetes.
- For those who want to consume carbohydrates, daily consumption can be between 2-10g per
kg of body weight of daily calories depending on activity level. I would suggest the lower limit
for those who are not very active, and the upper limit would be for highly active athletes.
- It is absolutely ok to eat a low carb diet if that is what works for you! Your body is amazing and
can make glucose as its needed to keep your brain, your nervous system and your red blood
cells functioning if you are not consuming enough through your diet.
Examples of Simple carbohydrates
-Honey
-Maple syrup
-White sugar
-Cane sugar
-Molasses
-Fruit juices
-Pop
-Corn syrup
-Pastries
-Jams
-Candy
Examples Complex carbohydrates
-All vegetables: spinach, kale, green beans, peas, carrots, peppers, tomatoes, broccoli, celery,
cauliflower, asparagus and much more (veggies will contain some carbohydrate but they will be
very low, mostly containing fibre)
-Sweet potatoes
-Beets
-Pumpkin
-Oats
-Barley
-Buckwheat
-Brown rice
-Whole grain wheat
-Millet
-Black beans
-Kidney beans
-Black eyed peas
Jeremie Premi CNP (in progress),
MNU Certified Nutritionist (in progress),
Dip. Culinary Arts.
Resources:
1 Gardner, Christopher et al (2018), https://pubmed.ncbi.nlm.nih.gov/29466592/
2 Hall, Kevin (2017), https://pubmed.ncbi.nlm.nih.gov/28074888/
3 Health Canada, https://www.canada.ca/en/public-health/services/diseases/type-2-diabetes.html
4 Gummeson, Anders (2017), https://pubmed.ncbi.nlm.nih.gov/28417575/