THE MACRONUTRIENTS: CARBOHYDRATES
Carbohydrates are an endlessly debated topic in nutritional science. On one side, there are low-carb proponents who claim carbohydrates are the root cause for a variety of modern health problems—from obesity to diabetes to heart disease. On the other side, there are those who think that carbohydrates serve essential functions for our well-being and have been unfairly vilified.
Stepping back to look at the intricacies of these complex molecules will help us to understand this debate more accurately, so we can make better choices for ourselves.
What are carbohydrates?
The term carbohydrate refers to a family of macromolecules ranging from simple sugar units to much larger, complex chains of sugars and other chemicals. Broadly, carbohydrates are classified by the number of units they contain. The most basic units are called monosaccharides. These smaller units can then be linked by chemical bonds to create progressively larger chains called polysaccharides.
The monosaccharides include familiar molecules like glucose, fructose, and galactose. When bonded in pairs, they form disaccharides, like maltose, lactose, and sucrose. As those bond further, they become lager polysaccharides, like starch, glycogen, cellulose, and chitin.
What types of carbohydrates are consumed?
We get most of our dietary carbohydrates from plants, like fruits, vegetables, grains, and legumes. That’s because carbohydrates provide the building materials for cell walls in the plants we eat. For example, cellulose is a common polysaccharide found in plants that gives them their rigid structure—helping them stand up straight and retain their shape.
Cellulose is an insoluble fiber, meaning it isn’t metabolized into the blood stream. Rather, it passes through our gastrointestinal system unabsorbed, providing food and nourishment for the symbiotic bacteria in our gut.
On the smaller side, there are simpler carbohydrates such as sugar. Sugar, known formally as sucrose, is made up of one glucose molecule and one fructose molecule. Fructose is what makes sugar sweet.
Disaccharides like sucrose are noticeably smaller and simpler than their polysaccharide counterparts. As a result, they have very different effects in the body. Simple carbohydrates are digested more rapidly than complex ones, which is an important part of the narrative as it relates to low-carb dieting claims. Simple carbohydrates also lack many of the other elements commonly found alongside more complex ones, such as fibers, vitamins, and minerals.
What do carbohydrates do in the body?
Complex carbohydrates such as fruits and vegetables digest more slowly because they have large, branched, and more complex structures surrounding them compared to simple sugars. Ultimately, they’ll all be metabolized into their smallest component parts, monosaccharides, it really just comes down to how long that process takes to occur.
Once glucose molecules are present in the blood our bodies have to deal with it. To do this, our pancreas secretes a hormone called insulin. Insulin’s job is to shuttle these molecules into cells to be used for energy production. Muscle, brain, organ and other tissue cells all utilize glucose for cellular respiration. Glucose is the basic substrate cells use to stay alive and carry-out their functions.
So what’s all the drama with carbohydrates?
The complicated story of carbohydrates
It seems clear that complex carbohydrates are more nutritious than simple ones, so it would be easy to write-off those darned white sugars. As many health gurus on YouTube might have you believe, sugar is the devil and insulin is its minion, right? Maybe.
Maybe not.
Let’s look at the bigger picture.
First, simple and quick carbohydrates don’t inherently equal bad news. If an athlete is performing a substantial amount of high-intensity training that requires large amounts of energy on-demand, does it make sense to give him or her very slow-digesting kale leaves that they won’t have energy access to for several hours?
Probably not. Cue, the white rice.
Second, we now know that different bodies will actually respond uniquely to sugars, even simple ones. The glycemic index has been a popular tool for investigating which carbohydrates digest most quickly, but recent research has demonstrated that even the simplest sugars could digest rapidly in one body and then more slowly in the next. One person’s blood sugar may spike after a banana, whereas another person could consume several cookies and still not experience high blood sugar levels.
Why’s this?
It appears to be due to a multitude of factors, including genetics, training status, lean body mass percentage, health history, movement patterns, and other metabolic behaviors.
Third, we want to think about all macronutrients in the greater context of total energy consumption. The common story is that carbs spike our blood sugar and when this occurs for long, we induce insulin resistance which causes metabolic dysfunction. But keep in mind: that’s in the context of a hypercaloric diet. In other words, chronic overnutrition of any kind continues to show itself as the key issue. In fact, recent evidence suggests that insulin resistance is not just the simple story of cells refusing to uptake any more sugar. It’s actually the result of cell dysfunction stemming from free radical damage. And this damage can be induced by overnutrition of all substrates.
“Chronic overnutrition and physical inactivity are major risk factors for insulin resistance and type 2 diabetes. Recent research indicates that overnutrition generates an increase in hydrogen peroxide (H2O2) emission from mitochondria, serving as a release valve to relieve the reducing pressure created by fuel overload, as well as a primary signal that ultimately decreases insulin sensitivity.” -Fisher-Wellman and Neufer 2011
Therefore, we have to think about the body as a whole system that’s responding to total energy intake and output, and then also consider that system in the context of pressure and inflammation. One study in 2009 discovered–contrart to everyone’s previously conceived notions of carbs–that fat can also induce insulin resistance!
“Surprisingly, switching rats from a standard high-carbohydrate chow diet to 100% fat (lard) for 3 days or a 60% high-fat diet for 3 weeks induced a remarkable 3- to 4-fold increase in the maximal rate of mitochondrial H2O2 emission” (Anderson 2009).
In large studies, weight loss groups tend to lose the same amount of weight whether they’re on a low-carb and high-carb diet so long as the diet is nutritious and the person exercises regularly. A major intervention studied demonstrated this more recently, in the Diet FITS clinical trial:
“In this clinical trial of 609 generally healthy overweight or obese adults without diabetes who were randomly assigned to a healthy low-fat vs a healthy low-carbohydrate diet, there was no significant difference in weight loss at 12 months. In addition, there were no significant interactions between diet and 3 SNP multilocus genotype patterns or diet and baseline insulin secretion on 12-month weight loss. These results were observed in the context of similar mean 12-month weight loss in both diet groups that was greater than 5% of baseline body weight…” (Gardner et al 2018).
In the Diet FITS trial, subjects were given whole food diets with properly balanced calories and counselled participants on recognizing signs of fullness and satiety at mealtimes.
So what does this mean for us?
At a minimum, it shows that nourishing carbohydrates can be a totally healthy component of a nutritious diet, despite claims to the contrary. But it also tells us that our movement and energy balance allow for diversity of nutrients.
Lastly, there is something essential to consider when we are examining the diet as a whole. Processed food tends to be comprised of simple carbohydrates AND fat. This combination is what we call “hyperpalatable.” When something is sweet and fatty (creamy, smooth, thick…etc), it’s easy to eat a lot of it, and it’s hard to stop. Thus, when deciding which carbohydrates, fat, and protein to eat, its ideal to trend towards minimally processed food choices. This helps naturally manage calories, makes people feel full, and allows people to eat higher volumes of food.
Carbohydrates and You
It can feel complicated to consider all of the information above–and no doubt, it is complex science–but we also can zoom back out to the big picture.
Here’s what we know:
- Carbohydrates come in many forms. Complex carbohydrates tend to be more nutritious, by offering fibers, vitamins, minerals, and phytonutrients.
- In the context of too many calories consumed, carbohydrates can contribute to negative health outcomes.
- Hyperpaltable carbohydrates should be minimized in any diet. They’re easy to overconsume and offer little nutritional value.
- People who exercise frequently and intensely process carbohydrates more efficiently than those who don’t.
- Simple stories in social media about carbohydrates being the enemy are not approaching the subject with nuance. It’s key to see the details in the context of a broader picture.
Above all else, the key is to view the details without losing sight of the greater vision: you. If you’re not moving enough–which is at least 150 minutes of moderate to vigorous exercise each week plus 8,000 or more steps daily–then there’s a reasonable chance that carbohydrate needs are somewhat low. In which case, sticking to fibrous fruits and vegetables when selecting carbohydrates at mealtimes is ideal. If you’re training hard, moving more, or aiming to improve performance, then taking advantage of simpler carbohydrates around workouts may be appropriate.
Overall, it’s essential to do some detective work when looking at the simple stories or quick fixes of nutrition discussions today. They almost always require more nuance than they’re given, and the true needs and uses of foods will be unique to each person.
THE MACRONUTRIENTS: CARBOHYDRATES
Carbohydrates are an endlessly debated topic in nutritional science. On one side, there are low-carb proponents who claim carbohydrates are the root cause for a variety of modern health problems—from obesity to diabetes to heart disease. On the other side, there are those who think that carbohydrates serve essential functions for our well-being and have been unfairly vilified.
Stepping back to look at the intricacies of these complex molecules will help us to understand this debate more accurately, so we can make better choices for ourselves.
What are carbohydrates?
The term carbohydrate refers to a family of macromolecules ranging from simple sugar units to much larger, complex chains of sugars and other chemicals. Broadly, carbohydrates are classified by the number of units they contain. The most basic units are called monosaccharides. These smaller units can then be linked by chemical bonds to create progressively larger chains called polysaccharides.
The monosaccharides include familiar molecules like glucose, fructose, and galactose. When bonded in pairs, they form disaccharides, like maltose, lactose, and sucrose. As those bond further, they become lager polysaccharides, like starch, glycogen, cellulose, and chitin.
What types of carbohydrates are consumed?
We get most of our dietary carbohydrates from plants, like fruits, vegetables, grains, and legumes. That’s because carbohydrates provide the building materials for cell walls in the plants we eat. For example, cellulose is a common polysaccharide found in plants that gives them their rigid structure—helping them stand up straight and retain their shape.
Cellulose is an insoluble fiber, meaning it isn’t metabolized into the blood stream. Rather, it passes through our gastrointestinal system unabsorbed, providing food and nourishment for the symbiotic bacteria in our gut.
On the smaller side, there are simpler carbohydrates such as sugar. Sugar, known formally as sucrose, is made up of one glucose molecule and one fructose molecule. Fructose is what makes sugar sweet.
Disaccharides like sucrose are noticeably smaller and simpler than their polysaccharide counterparts. As a result, they have very different effects in the body. Simple carbohydrates are digested more rapidly than complex ones, which is an important part of the narrative as it relates to low-carb dieting claims. Simple carbohydrates also lack many of the other elements commonly found alongside more complex ones, such as fibers, vitamins, and minerals.
What do carbohydrates do in the body?
Complex carbohydrates such as fruits and vegetables digest more slowly because they have large, branched, and more complex structures surrounding them compared to simple sugars. Ultimately, they’ll all be metabolized into their smallest component parts, monosaccharides, it really just comes down to how long that process takes to occur.
Once glucose molecules are present in the blood our bodies have to deal with it. To do this, our pancreas secretes a hormone called insulin. Insulin’s job is to shuttle these molecules into cells to be used for energy production. Muscle, brain, organ and other tissue cells all utilize glucose for cellular respiration. Glucose is the basic substrate cells use to stay alive and carry-out their functions.
So what’s all the drama with carbohydrates?
The complicated story of carbohydrates
It seems clear that complex carbohydrates are more nutritious than simple ones, so it would be easy to write-off those darned white sugars. As many health gurus on YouTube might have you believe, sugar is the devil and insulin is its minion, right? Maybe.
Maybe not.
Let’s look at the bigger picture.
First, simple and quick carbohydrates don’t inherently equal bad news. If an athlete is performing a substantial amount of high-intensity training that requires large amounts of energy on-demand, does it make sense to give him or her very slow-digesting kale leaves that they won’t have energy access to for several hours?
Probably not. Cue, the white rice.
Second, we now know that different bodies will actually respond uniquely to sugars, even simple ones. The glycemic index has been a popular tool for investigating which carbohydrates digest most quickly, but recent research has demonstrated that even the simplest sugars could digest rapidly in one body and then more slowly in the next. One person’s blood sugar may spike after a banana, whereas another person could consume several cookies and still not experience high blood sugar levels.
Why’s this?
It appears to be due to a multitude of factors, including genetics, training status, lean body mass percentage, health history, movement patterns, and other metabolic behaviors.
Third, we want to think about all macronutrients in the greater context of total energy consumption. The common story is that carbs spike our blood sugar and when this occurs for long, we induce insulin resistance which causes metabolic dysfunction. But keep in mind: that’s in the context of a hypercaloric diet. In other words, chronic overnutrition of any kind continues to show itself as the key issue. In fact, recent evidence suggests that insulin resistance is not just the simple story of cells refusing to uptake any more sugar. It’s actually the result of cell dysfunction stemming from free radical damage. And this damage can be induced by overnutrition of all substrates.
“Chronic overnutrition and physical inactivity are major risk factors for insulin resistance and type 2 diabetes. Recent research indicates that overnutrition generates an increase in hydrogen peroxide (H2O2) emission from mitochondria, serving as a release valve to relieve the reducing pressure created by fuel overload, as well as a primary signal that ultimately decreases insulin sensitivity.” -Fisher-Wellman and Neufer 2011
Therefore, we have to think about the body as a whole system that’s responding to total energy intake and output, and then also consider that system in the context of pressure and inflammation. One study in 2009 discovered–contrart to everyone’s previously conceived notions of carbs–that fat can also induce insulin resistance!
“Surprisingly, switching rats from a standard high-carbohydrate chow diet to 100% fat (lard) for 3 days or a 60% high-fat diet for 3 weeks induced a remarkable 3- to 4-fold increase in the maximal rate of mitochondrial H2O2 emission” (Anderson 2009).
In large studies, weight loss groups tend to lose the same amount of weight whether they’re on a low-carb and high-carb diet so long as the diet is nutritious and the person exercises regularly. A major intervention studied demonstrated this more recently, in the Diet FITS clinical trial:
“In this clinical trial of 609 generally healthy overweight or obese adults without diabetes who were randomly assigned to a healthy low-fat vs a healthy low-carbohydrate diet, there was no significant difference in weight loss at 12 months. In addition, there were no significant interactions between diet and 3 SNP multilocus genotype patterns or diet and baseline insulin secretion on 12-month weight loss. These results were observed in the context of similar mean 12-month weight loss in both diet groups that was greater than 5% of baseline body weight…” (Gardner et al 2018).
In the Diet FITS trial, subjects were given whole food diets with properly balanced calories and counselled participants on recognizing signs of fullness and satiety at mealtimes.
So what does this mean for us?
At a minimum, it shows that nourishing carbohydrates can be a totally healthy component of a nutritious diet, despite claims to the contrary. But it also tells us that our movement and energy balance allow for diversity of nutrients.
Lastly, there is something essential to consider when we are examining the diet as a whole. Processed food tends to be comprised of simple carbohydrates AND fat. This combination is what we call “hyperpalatable.” When something is sweet and fatty (creamy, smooth, thick…etc), it’s easy to eat a lot of it, and it’s hard to stop. Thus, when deciding which carbohydrates, fat, and protein to eat, its ideal to trend towards minimally processed food choices. This helps naturally manage calories, makes people feel full, and allows people to eat higher volumes of food.
Carbohydrates and You
It can feel complicated to consider all of the information above–and no doubt, it is complex science–but we also can zoom back out to the big picture.
Here’s what we know:
- Carbohydrates come in many forms. Complex carbohydrates tend to be more nutritious, by offering fibers, vitamins, minerals, and phytonutrients.
- In the context of too many calories consumed, carbohydrates can contribute to negative health outcomes.
- Hyperpaltable carbohydrates should be minimized in any diet. They’re easy to overconsume and offer little nutritional value.
- People who exercise frequently and intensely process carbohydrates more efficiently than those who don’t.
- Simple stories in social media about carbohydrates being the enemy are not approaching the subject with nuance. It’s key to see the details in the context of a broader picture.
Above all else, the key is to view the details without losing sight of the greater vision: you. If you’re not moving enough–which is at least 150 minutes of moderate to vigorous exercise each week plus 8,000 or more steps daily–then there’s a reasonable chance that carbohydrate needs are somewhat low. In which case, sticking to fibrous fruits and vegetables when selecting carbohydrates at mealtimes is ideal. If you’re training hard, moving more, or aiming to improve performance, then taking advantage of simpler carbohydrates around workouts may be appropriate.
Overall, it’s essential to do some detective work when looking at the simple stories or quick fixes of nutrition discussions today. They almost always require more nuance than they’re given, and the true needs and uses of foods will be unique to each person.