Are Carbs Good or Bad?
Updated: Jan 24, 2019
Many people suffer from a condition known as carbophobia: an intense or obsessive avoidance of carbohydrates. This is clear by the rampant popularity of low carb diets such as keto and the 30,000+ Instagram hashtags that appear when you search “war on carbs”.
On one hand, this is an extreme movement that is unfairly vilifying an entire macronutrient. On the other hand, I can sympathize with the anti-carb cult - a common theme that I hear from clients is that they are tired of conflicting nutrition advice - back in the 80’s we were told that fat is bad for us so we avoided fat like the plague. Then people started gaining weight, so we decided carbohydrates were to blame for our obesity epidemic. But are carbs really as evil as people make them out to be? Below you’ll find my answers to the most frequently asked carb questions.
What is a carbohydrate anyway?
Carbohydrates are our body’s primary source of energy, and are simply long chains of hydrogen and carbon molecules.
Carbs can be made up of the following 3 components:
Sugar - i.e simple sugars like fructose and glucose which require very little work for our body to break down (examples are fruit juice and chocolate bars)
Starch - i.e a bunch of sugar molecules packed together in a dense arrangement. The body has to work much harder to metabolize starches, and their release into the bloodstream is much more gradual (think rice, pasta, and beans)
Fibre - a type of carbohydrate humans can't digest. Fibre is the stuff that travels down into our colon where our bacteria feast on it and turn it into ultra beneficial anti-cancer and anti-inflammatory compounds called short-chain fatty acids. Fibre is only present in PLANTS so you will never find it in animal products like milk or eggs.
Now based on the above information, you might be thinking that foods with more fibre and starches are better than foods higher in simple sugars. While this may be true most of the time, there are cases when simple sugars are in fact more desirable.
Here's an example: the cyclist in this photo is 2 hours into a race and eats an energy waffle made out of simple sugars. This waffle will be much more conducive for replenishing his muscle glycogen stores FAST so that he doesn’t experience that feeling of “hitting a wall” when all the sugar stores in his body are depleted. So although fibre is important for health and deserves an article of its own, it’s not something the cyclist would want to consume in large quantities during a race because of the gastrointestinal distress it may cause. What he needs is something that will break down and enter the bloodstream efficiently like a sports drink, scone, or another high glycemic food.
I hope this illustrates that there is no such thing as “good” or “bad” carb, and that context is everything.
Despite what you may have read in sensationalized books such as "Grain Brain", gluten is not a"silent germ", nor is it responsible for our obesity epidemic. Demonizing gluten may be great for fattening Mr. Perlmutter’s wallet, but it doesn't make for a very compelling argument. Yes, we are eating more sugar and refined carbs than we did 4 decades ago. But guess what else has changed since then?
Portion sizes increased.
We are consuming more calories PERIOD.
We are leading more sedentary lifestyles.
Remember, obesity is a complex and multi-factorial issue, meaning there are many different risk factors besides a person's diet such as genetics, age, ethnicity, sex, environment, and lifestyle. Another aspect that books such as Grain Brain fail to address, is the fact that carbs are not only white bread and cookies. The less talked about categories include:
Fruits - (which contain naturally occurring fructose)
Milk products - (which contain naturally occurring lactose, but also have added sugars if the yogurt is flavoured)
Starchy vegetables (potatoes, beets, and corn)
Grains (oats, quinoa, and rice)
Pulses (beans, chickpeas, and lentils)
So why do carbs have such a bad rep? Likely because as a population, we are overindulging on the less desirable ones. You know, the ones that contain added sugars like high fructose corn syrup - which is added to everything from baked goods to salad dressings. We also tend to consume refined carbohydrates more often than whole grains. Items like wonder bread, white rice, and highly processed cereals like captain crunch that have been stripped of the fibre and rendering it a "not so healthy food". These foods are less filling since they are missing fibre and protein, and are more likely to contribute to overeating and weight gain.
Do we need carbs?
Glucose is so important for life that even if we don't consume a single gram of sugar, our body would still be able to produce it endogenously in order to maintain a certain level of sugar in the blood (by turning amino acids from protein into glucose via gluconeogenesis as one example). So technically from a survival perspective, the answer is no. HOWEVER, from the perspective of optimizing our health, carbohydrates from the first 5 categories are key players when it comes to supplying our body with important nutrients and phytochemicals.
For example, sweet potatoes are rich in 2 important antioxidants: beta-carotene and vitamin C - just one medium sweet potato provides more than 100% of the recommended daily intake of beta carotene, a phytonutrient that contributes to eye, skin, and immune system health. Whole grains like oatmeal and quinoa are rich in magnesium, and iron - 2 minerals that are crucial for many functions in the body and which many Canadians are deficient in. Milk products like Kefir are not only the best source of calcium, but also contain live probiotics which are essential for gut health and aid digestion.
So although there is nothing wrong with going keto (surely our bodies have evolved with the ability to go into ketosis for a reason), you have to understand which nutrients and phytochemicals you are compromising as a result of drastically limiting carbohydrates. This means doing keto the right way with the help of a dietitian, and possibly supplementing whatever is lacking in the diet.
Shouldn’t I avoid whole grains because of the “anti-nutrients” ?
There are some people who are worried about consuming whole grains due to the supposed “anti-nutrients” like phytates. Although phytates do theoretically bind to minerals like iron, zinc, and calcium, and potentially affect their absorption, there are no research papers suggesting whole grains cause mineral deficiencies in humans. The only exception to this are people who live in developing countries and consume a diet very high in specific grains and legumes. If you live in North America, chances are your diet is diverse enough to counteract the tiny amount of minerals that are bound and lost to phytates.
And guess what...dark leafy greens like spinach are also high in anti-nutrients called oxalates. Does this mean we should stop eating our greens? Absolutely not since these veggies are abundant in a whole host of nutrients including magnesium - a cofactor for over 300 different enzymes in the body and a mineral many of us aren’t getting enough as is.
Who benefits from eating a ton of carbs?
Carbohydrate needs vary from person to person, and even our own needs are going to vary from one day to the next. Requirements will depend on age, gender, activity level, genetics, and overall caloric needs. Since there’s no such thing as a magical combination of macros that is going to work for everyone, we often have to experiment with our diet to see what works best for our body type and goals.
As a general statement, anaerobic moderate to high intensity activity is powered by carbohydrates. We store the sugar we eat in our muscle as glycogen, and this is the most efficient fuel source when we engage in activities like weight lifting, crossfit, or high intensity endurance sports. So yes, these individuals will have a much greater reliance on carbs than a person who is sedentary. What happens if this individual is not getting enough carbs from their diet? As the duration of the high intensity workout increases, the body may start to oxidize protein instead and muscle tissue may be compromised as a result. Obviously this is not desirable since muscle mass is key for boosting metabolism!
Is a low carb diet superior for weight management?
Low carb diet proponents will often tell you that this is a superior method for weight loss. There are 2 issues with this statement: 1) Every gram of carb stored in your body as glycogen holds about 2-3 grams of water. So the rapid weight loss that occurs on diets like keto is usually water weight, and not actually fat loss. 2) Low carb diets are not always sustainable for individuals in the long run, and may lead to weight cycling in certain individuals.
Johnston and colleagues (2006) conducted a randomized control trial involving 20 obese individuals who were randomly assigned to either the ketogenic group (diet was 60% fat, 5% carbohydrate, and 35% protein) OR the non-ketogenic group (diet was 30% fat, 40% carbohydrate, 30% protein). The researchers did a good job mitigating any potential confounding variables - they made sure total protein and calories were equal in both groups, prepared the meals themselves, and instructed the participants in both groups to refrain from any physical activity.
After 6 weeks, there was no significant difference in weight or body fat reduction between the groups.
Since we can't make any inferences based on one study alone, let's take a look the results of a meta-analysis by Naude and colleagues, which pooled together data from 19 different studies and 3209 participants.
The authors concluded that"there is probably little or no difference in changes in weight and cardiovascular and diabetes risk factors with low carbohydrate weight loss diets compared to isoenergetic balanced weight loss diets."
Remember, it's possible to lose weight on both a low carb and a high carb diet, so long as there is a calorie deficit. Some people like keto because of the appetite suppressing effect this diet has and the preference for strict parameters. For others, a less extreme diet with higher protein and moderate fat/carbs is the easiest way to achieve a deficit and maintain their weight in the long run.
We need to stop blaming carbohydrates for the world's problems and let go of these rigid ideas we have around food. We are constantly evolving which means our diets may change at various stages of our lives. I am not advocating for Wonder Bread or sugary cereals, but I do encourage my clients to seek out the right types of carbs such as fruits, sweet potatoes, and sprouted whole grains. Unless you have a medical condition such as type 2 diabetes, there is really no reason to cut out these foods from your diet, especially if you are someone who leads an active lifestyle.
Lisa Makeeva RD MAN