Carbs Are Confusing
“Health and appetite impart the sweetness to sugar, bread and meat.”
- Ralph Waldo Emerson
Carbohydrates are controversial since there are so many misconceptions. Sugar is a carb and isn’t it public enemy #1? Wait, all whole vegetables are primarily carbs, so are carbs actually healthy?
Why referring to carbs as a broad category is misleading?
The term "carbohydrate" was coined by German chemist Carl Schmidt in 1844. In nerd speak, “carbo" implies carbon and “hydrate" implies hydrogen and oxygen. Carl Schmidt could never have imagined his coined term would be used for centuries describe one of the 3 major compounds found in food (aka macronutrients).
What most people don’t appreciate is that carbohydrates, as defined on US food labels, come in 3 distinct types:
Fiber: Not broken down in the gut and remains fiber in the digestive tract. Examples of high fiber foods are whole vegetables, especially cruciferous ones (e.g. broccoli, cauliflower)
Starch: Broken down into glucose in the digestive tract. Examples of high starch foods are potatoes, bread and pasta.
Sugars: Broken down into fructose and glucose in the digestive tract. Examples of high sugar foods are stone fruit, candy and cake.
Referring to carbs as a broad category is useless since each of the components above can have vastly different effects on the body, both short-term and long-term. If the components are consumed out of balance over long periods, serious chronic conditions can develop (e.g. diabetes, liver disease, heart disease, etc).
The confusing part is all 3 of these compounds are typically part of a nutritious diet. Many foods will contain all 3 buckets as evidenced by any nutrition label. Total Carbs (shown on label) = Fiber (shown) + Starch (not shown) + Sugar (shown).
Fiber has a bad brand. Olipop has a good brand.
A challenge I see of balancing fibrous carbs (fiber) and non-fibrous carbs (starches and sugars) is that most people still don’t fully understand 1) what fiber is and 2) how it benefits our health.
When most people hear ‘fiber’, they primarily think of a powdery supplement like Metamucil or Citrucel to address constipation. The reality is that fiber is contained in many more foods than powdery supplements and its consumption has a much wider impact on our health.
Vegetables, especially cruciferous ones like broccoli or brussels sprouts, are key sources of fiber. It no surprise that the average American is deficient in fiber when the top 4 consumed vegetables in the US are: potatoes, tomatoes (actually a fruit), onions and carrots1. To varying degrees, all 4 have a poor ratio of fibrous to non-fibrous carbs. Another reason for our population’s fiber deficiency is that fiber is typically removed from ultra-processed foods for shelf-life and taste / texture considerations.
Olipop has made fiber cool again by including it in a fun form factor — less-unhealthy versions of classic soda flavors. Admittedly, most consumers are focused on the tasty soda alternative aspect over the 9 grams of fiber. America’s fiber deficient population can feel a bit warmer on the inside when making the incrementally healthier choice.
What else does fiber do besides aid constipation?
Fiber is food for the trillions of bacteria in your microbiome enabling a healthy gastro-intestinal tract and homeostasis. All fibrous foods2 are the building blocks of a healthy microbiome, which regulates a vast quantity of processes and hormones.
Additionally, fiber is a key regulator of our blood glucose levels, which can vary widely within each day depending on 1) what you eat and 2) how you eat it (i.e. what goes into the stomach before, during or after).
Fiber modulates the breakdown and absorption speed of glucose from non-fibrous carbs in the gut. In other words, eating broccoli with a bowl pasta versus eating pasta alone will meaningfully impact how the pasta (and its downstream glucose) is broken down and absorbed by the small intestine3. The frequency and amplitude of the resulting glucose “spike”4 may affect some people greatly whereas other may be completely fine.
Jessie Inchauspé, in her book Glucose Revolution, evangelizes fiber and references a 2015 research paper from Cornell Weil Medical College5 suggesting that eating foods with a high ratio of fibrous carbs *before* foods rich in protein, fat and starch / sugar (i.e. non-fibrous carbs), ideally in that order, can meaningfully affect a person’s metabolism and feelings of satiety. Digestion varies greatly across individuals but anecdotal evidence from her “Glucose Goddess” online community indicates that many people benefit from this approach.
Is Inchauspé’s “fiber timing” diet just another fad?
Yes and no. Yes, because all “diets” are by definition fads unless they can be easily sustained for a lifetime (after gradual ramp up). No, because the benefits of more fiber consumption is nearly universally recommended by the medical community — as such, any fiber-rich diet is better than the status quo. Importantly, more research is needed on how impactful “fiber timing” can be since the Cornell study only had a sample of 11 participants.
Can one consume too much fiber?
Genetically, there is variability across individuals in how much fiber they can comfortably consume each day. The general recommendation is 25-35 grams daily, depending on weight. Adults in the US are consuming on average 10-15 grams daily6. Ancestral humans might have consumed as much as 100 grams of fiber daily7. For some, adding more fiber may need to be gradual. Our gut microbiome, similar to our taste buds, will need time to adjust.
The misconception of carbs delivering sustained energy
The hypothesis that humans need starchy carbs for sustained energy, particularly in the morning, has been largely debunked8. Humans burn either glucose or fat as a source of energy. For both genetic and environmental reasons, some people are more metabolically flexible and can more easily switch between burning glucose and fat. The body prioritizes burning glucose and, depending on several factors (e.g. meal timing, nutrition, exercise, sleep duration, hormones), it will switch to burning fat for fuel after a longer period between meals.
A bowl of cereal in the morning may be fine some people (e.g. long-distance runners, highly active children). Others, like me, will eat a meal rich in glucose and get hangry 1-2 hours later due to a measurable glucose “spike” and crash. For those, a breakfast full of non-fibrous carbs (cereal, toast, bagels) causes a rollercoaster of cravings throughout the day. A breakfast richer in fibrous carbs (chia pudding), protein (eggs), and healthy fats (avocado) will likely deliver more sustained energy9.
Bonus questions: Are some some sugar sources worse than others? What about sugar alternatives?
Some nutrition nerds may focus on “added sugars” vs total sugars. However, all sugar is broken down into either glucose or fructose. The shape of each respective molecule is exactly the same whether the sugar came from table sugar, agave, maple syrup, berries, coconuts, or any other source. Sugar can be diluted with water and fiber (as in whole fruit) and have what’s known as a lower glycemic index, but it’s still the same sugar.
While the research is still not robust on many sugar substitutes, there is a general consensus today that monk fruit extract, stevia and allulose are likely to be suitable alternatives in modest doses10. Interestingly, these alternatives have a sweet taste on the tongue but effectively pass through the gut without being broken down, similar to fiber.
There is a lot of nuance and power in the kingdom of carbohydrates. Good luck out there!
It is possible to further stratify fiber into insoluble, soluble, prebiotic, etc. However, fiber found in whole vegetables and fruits typically includes all such subcomponents in varying ratios.
These spiks are have become much easier to measure real-time with prescribed or over-the-counter continuous glucose monitors (CGMs)
This assumes you are not an endurance athlete where carb loading may still be beneficial before a 2+ hour race.