Sugar, Starches, Fiber and More
Carbs get a bad rap, but it's misguided. We do our best to simplify the science, and also cover resistant starch
Obesity is a growing problem for pets in the US and Europe, as more than 60% of dogs classify as overweight. Carbohydrates often get the majority of the blame for both dogs’ and peoples’ problems, but it’s not that simple. Carbohydrates are a huge classification of molecules, many of which are actually indigestible.
Today we cover why the hate for carbs is misguided. We cover some literature, explain the differences between carbs, and simplify their role in a healthy diet for you and your pups.
Before that here’s this week’s recipe: Chow Mein (fittingly low carb)
For most things, simple is better…NOT WITH CARBS!
Carbohydrate, in its most basic form, is considered to be glucose, a sugar. When health care providers talk about blood sugar, they are referring to how much glucose is dissolved in the blood. When people consume pure glucose or refined carbohydrates, it gets metabolized very quickly and spikes blood sugar. Frequent blood sugar spikes are harmful for several reasons.
High blood sugar stresses the endocrine system and causes the pancreas to work harder.
Blood sugar spikes also result in blood sugar crashes, which may increase hunger and create a spike-crash cycle.
Increased blood sugar and increased insulin lead to weight gain, metabolic syndrome and chronic disease.
Pure glucose is not readily available in nature. It’s usually locked up in fruits or plants, and typically only makes up a small portion of carbohydrates. To store glucose, plants connect them into chains of increasing complexity, from more complex sugars to starch.
The more complex the carbohydrate, the longer it takes to break down and turn into the glucose that raises blood sugar. Fiber, which usually accompanies sugar and starches, also slows down digestion giving a nice, slow and even release of glucose into the blood stream. More on fiber below.
Carbohydrates in today’s food supply are usually refined to increase purity and remove fiber. Breads, crackers, cookies and pasta are made to be very calorically dense because it’s cheaper to transport per calorie and more appealing to our animal brains. These refined carbohydrates break down into sugars very quickly, causing blood sugar spikes.
Glycemic index (GI) is a measure to understand how foods impact blood sugar. Meat is 0 and glucose is 100, while table sugar is 65. Many common foods have glycemic index values even greater than table sugar, like white bread, corn flakes and rice cakes.
Although GI is not measured in dog food, kibble is typically made with refined carbohydrates. According to this study, increases in carbohydrate content in dog food negatively affect blood sugar metrics uniformly.
We use the following for our pups and ourselves:
Whole grains like quinoa, steel cut or rolled oats (instant oats have a much higher glycemic index)
Vegetables like sweet potatoes, carrots, beets and squash
Fruits like berries, melons and apples
When consuming refined carbohydrates, it’s important to ensure that they are consumed in moderation, with fiber, and ideally with proteins and fats.
Sugar is not evil, it’s required by the body
Sugar is a basic nutrient in dogs and humans, as glucose is the preferred fuel of the brain. However, some cells, like red blood cells can only run on glucose. This is one of the main reasons there is sugar in the blood at all!
Throughout our time on earth, we were mostly deprived of food. So our genes evolved to store as much energy on our bodies as possible in fat. Sugar, in the form of fruits and honey, was only available for a short time during summer in most parts of the world. So humans were wired to crave sugar to help their bodies make it through the winter when food was scarce. Now that sugar can be found everywhere, at all times, our bodies’ cravings no longer serve us.
Yet, sugar is so essential, that nature created a process to make sugars from proteins and fats called gluconeogenesis. Even when a dog is starving, they still will have small amounts of sugar in their blood that is made through this process. Carbohydrates are not considered to be essential nutrients simply because both dogs and people can make them.
However, making glucose takes more energy than consuming it because it needs to be put together from smaller parts. The difference is like cutting fabric into a piece of cloth versus making cloth from thread. For this reason, we believe feeding complex carbohydrates is good for dogs and people. A better question than, if they should have carbs, is what type and how much do they need? For healthy dogs we tend to keep calories from carbs at 20% or lower, while weight loss formulations are 10% or lower.
All about fiber
Starches are stored inside the cell walls of plants, which is made of cellulose. Cellulose is a dietary fiber, which is also a complex carbohydrate because it is made up of glucose molecules. BUT, because the type of bond between the glucose molecules is different than starches, fiber is indigestible by pups and people.
In fact, cows can’t directly digest fiber either, and rely on bacteria in their guts to break down cellulose and release the glucose. Dogs (and people) also have bacteria that live in their guts that can break down some of the fiber, but most is undigested and passes through in the stools intact. Fiber is considered essential in humans and very helpful for dogs because it aids digestion and feeds beneficial bacteria in our guts.
In one study on loose stools in police dogs, 90% of the subjects administered 4 tablespoons of psyllium husk fiber per day showed a good or very good response. Soluble fiber, like the kind in psyllium husk, increases short-chain fatty acids from bacterial fermentation. In addition to helping with digestion, soluble fiber is beneficial for liver, heart and kidney function. See our previous post on veggies.
Why low carb works for weight loss
As we covered in our previous newsletter on pup weight loss, the literature converges on low carb, high fiber diets as being most beneficial for shedding a few pounds. This is because protein and fats help with satiation, the feeling of being full. Also, as proteins are required for optimal metabolic function, restricting protein impacts lean muscle mass. Furthermore, proteins and fats tend to be consumed together from animal sources, while carbohydrates are more easily restricted.
This doesn’t mean that carbs are bad. When, target weight is reached, easing back to normal levels of complex carbohydrates is a sound dietary strategy for both people and dogs.
And finally, what is resistant starch?
Resistant starch is starch that is changed to be more like fiber, so less of it is digested and it has less affect on blood sugar. Recently there are a lot of online influencers sharing about how to turn rice into resistant starch. We did a quick literature review to check these claims.
It’s true. Refrigerating cooked rice at low temperatures does reduce the glycemic index of rice. See this study on type 1 diabetics. There are other factors that can increase resistant starch, including a variety of processing techniques and also microwave cooking.
Conclusion
Vilifying carbohydrates is misguided. Glucose is required by many cells in the body, while fiber, especially soluble fiber, is very helpful for digestion and gut health in both people and dogs. The confusion comes from the type of carbohydrate that is available in modern diets. Breads, crackers and sweets are refined and are typically served without the dietary fiber that would accompany it in nature.
If you do eat refined carbs (we can’t resist bread), try to consume it after something that digests more slowly, like a fatty meal or something with fiber. Eating refined carbs on an empty stomach should be avoided. For your pups, complex carbohydrates from whole grains, fruits and veggies are a great part of a healthy diet.
That’s it for this week.
All the best,
Joelle and the Precious Creatures Team