Dr. Lieber’s Sugar Diatribe - Part 3

Dr. Lieber’s Sugar Diatribe, Part 3 – Carbohydrates

Now that I have laid down some foundational information, I can detail what our bodies do with the different carbohydrates. I will be using the Standard American Diet (SAD) as a point of reference.

Here is a short video reminder of where we are from last week’s post:

What and Where Are All The Carbs?

The SAD has a typical macronutrient composition as follows:

• * Carbohydrates – 50%
• * Fats – 35%
• * Protein – 15%

A typical 2000 kcal diet/day would equate to approximately 1000 kcal of carbs/day. These carbohydrate calories can be broken down further into 3 separate subcategories as:

• * Complex Carbohydrates – whole grains, vegetables, legumes.
• * Simple Sugars – naturally occurring in dairy, fruits, and the added sugars and starches in processed foods.
• * Fiber – non digestible (cellulose) from whole grains, fruits, vegetables, legumes, seeds and nuts.
• Both complex (oligosaccharides) and simple carbs (disaccharides) will eventually be broken down in the intestines into their smallest units (monosaccharides). These units are in the form of glucose, fructose (the sugars from fruits and vegetables), and galactose (the sugars from dairy). These simple molecules will then be absorbed into the bloodstream and transported to cells for energy production. The fiber portions of carbohydrates serve as bulk and will also act as important resources for balancing our natural intestinal flora (gut biome). This fiber is also critical in the metabolism and synthesis of various vitamins and enzymes.

A Sugar By Any Other Name

This lesson becomes a bit more complicated when food manufacturers’ purposely use vague and healthful sounding names as added sugars:

Various Names of Sugars

You may recognize a good number of these and think of them as ‘healthy’. They may taste different from table sugar, but even these so called ‘healthy substitutes’ are simply just another simple sugar. Once you recognize all the ways which manufacturers slip the sweets into our foods, you will begin to see that it is everywhere and in everything.

The Ups and Downs
As carbohydrates are broken down in the intestines and enter the bloodstream, your blood sugar levels rise. This activates the pancreas to secrete insulin hormones. The insulin pushes the sugar from the bloodstream to your cells for use as energy. When there is more sugar in your blood than you need, the insulin will then push the excess into your muscles and liver. Once there, it will be converted into the complex storage molecule called glycogen (polysaccharide). On average, your glycogen stores contain about a day’s worth of energy resources.

So what happens if your blood sugar levels are still high but your sugar storage tanks (muscle & liver) are full? Well, this is not a healthy situation. This poses a problem because there are real risks of having too much sugar in our blood stream. I will get into the details about these risks further in the future. For now I can simply say that any excess glucose that is not used by the body for energy, and cannot be stored as glycogen, will then be converted and stored as fat.
Interestingly, in the absence of carbohydrates (a few hours after you eat), blood sugar levels start to drop. Your pancreas then stops producing insulin and blood sugar levels drop low enough for us to get hungry again. This paired rise and fall sequence happens each time we eat a meal as shown below.

Insulin Sugar Graph

So what are the various physiological effects from different types of carbohydrates? And why do they call some carbs “good” while others “bad”?

Complex carbohydrates are so named because they are indeed complex. Their sugars are not monosaccharides and they also contain fiber, vitamins, minerals, enzymes and prebiotics (different than probiotics which occur in fermented foods). In contrast, simple carbohydrates are called simple because of the lack of complexity of the saccharide chain molecule and are also missing the above healthful ingredients. They are essentially ‘empty’ starches or sugars.
One challenging aspect about this information is that not all complex carbohydrates are considered “good carbs”. This is because some of them tend to raise our blood sugar very quickly as do simple carbs. Whole and complex carb foods such as raisins, dates, cooked carrots, white potatoes, corn, beets, beans, white rice, peas, kiwi and watermelon would be considered bad for this reason. Making the distinction between a “good” and “bad” carb can make all the difference to our health.

So, how can we figure out which carbs are which? Simply by using a term called Glycemic Index (GI). The GI was created to measure the speed with which carbohydrates are converted to glucose. Foods that digest quickly (the bad kind) are high on the index. Foods that digest slowly (the good kind) are lower on the index. This is important because large spikes in insulin levels affect your hunger (can make you even more hungry), can negatively impact fat loss, and even lead to diabetes and a host of other health issues.

Here is a graph to help explain the differences in time of metabolism of high versus low GI foods:
High and Low GI Foods

Side Note: Just because you may only be eating low GI foods it does not necessarily mean that you are safe from risks. The over indulgence in even ‘good’ carbs can lead to the same health issues. I will address this possibly complicated idea further in up and coming posts.

For a (nearly) complete list of carbs and their GI, click here: Glycemic Index Food List
Next week we continue expanding the digestion and metabolism conversation. I will be focusing on the conversion of glucose into energy and diving a bit deeper into some theories about how we lose and gain weight. Stay tuned.

http://matthewlieber.com/2018/09/13/dr-liebers-sugar-diatribe-part-3-carbohydrates/