One of the largest diet debates is over low carbohydrate diets. This controversy is something that I usually stay miles away from because most people base their opinion about low carbohydrate diets on unreferenced magazine or newspaper articles, misleading websites or biased opinions from television commentators. Many times, I hear conversations about low carb diets starting with, “I heard that…” Hearsay, more commonly known as gossip, is a lousy way to begin formulating your personal opinions on anything! A conversation with someone that bases opinions on gossip isn’t going to help them, and since my purpose is to help people find ways to improve their health with diet, most of the time, the best thing for me to do is keep my mouth shut. Every once in awhile, I run into a situation where not saying anything can hurt people. Now is one of those times.
A very recent presentation at the European Society of Cardiology Congress caught my attention. It is based on a meta-analysis. As you will recall from my August 7 healthy eating tip about fiber, a meta-analysis is an extremely powerful research tool used to determine if “consensus” has been achieved. It is a separate study of the results of many other studies compiling extremely large sets of data. Remember that for researchers, scientists, doctors and medical team members, the term “direct causation” is almost an unattainable level of certainty. “Consensus” is a general agreement among the members of the scientific community about something. That is the closest that these folks every come to direct causation or “fact.” When researchers start making bold statements, it is an indication that consensus is forming. The debate is not over by any means, but recent bold statements about low carb diets indicate that there are new data worth looking at.
I’ve been reading this meta-analysis and the associated studies for about a week, and the findings are worth talking about. Before we do that in the next weeks, we need to first understand what carbohydrates are and how we can use that knowledge to help us lose weight and improve health today!
Macronutrients are the large categories of food that supply our bodies with calories. They are carbohydrates, proteins and fats. Carbohydrates are sugars and starches that are found in fruits, vegetables, grains, beans and processed foods. One gram of carbohydrates contains 4 calories. Contrary to popular belief, protein is in many foods, not just meat; animals get protein from plants. Beans and grains are an excellent source of protein. One gram of protein also contains four calories. Fat is found in just a few vegetables, but also nuts and seeds, and meat is almost always associated with some amount of fat. Processed foods usually have large amounts of fat in them. One gram of fat contains nine calories. One gram of alcohol contains seven grams of calories.
Carbohydrate: 1 gram = 4 calories
Protein: 1 gram = 4 calories
Fat: 1 gram = 9 calories
Alcohol: 1 gram = 7 calories
Carbohydrates are sugars and starches, also known as saccharides. They represent the primary food source for most living things on the planet. There are various types of carbohydrates. They include monosaccharides, disaccharides and polysaccharides.
Monosaccharides are the smallest possible sugar unit. Examples include glucose found in many foods, galactose found in milk, and fructose found in honey and ripe fruit. Glucose is a primary source of energy for a cell. “Blood sugar” is a measure of glucose in the blood.
Disaccharides are two monosaccharide molecules bonded together. Bonding one glucose molecule with a galactose molecule produces lactose. Lactose is commonly found in milk. Bonding one glucose molecule with a fructose molecule produces sucrose. Sucrose is found in table sugar.
Polysaccharides act as sugar or energy storage. In plants, it is called starch, and in animals, it is called glycogen.
Carbohydrates can combine to form polymers or chains. An important polymer or chain carbohydrate for us is called starch. Starches are glucose polymers (chains) that are made up of amylose and amylopectin. One reason we know that starch is an important food source for humans is that we have amylase enzymes. Amylase is present in our bodies to allow us to digest or break down large starch chains into the smaller sugar chains or monosaccharides that we then “burn” to create energy in our bodies. Starch is the way that plants store this energy as a polysaccharide, and glycogen is the way that animals, including humans, store energy as a polysaccharide. Glycogen is the fat we all see on our bodies.
Monosaccharides and disaccharides are also called simple sugars, and polysaccharides are also called complex sugar.
Simple sugars are a rapid source of energy for our bodies. Examples include white rice, white flours, white sugar and candies. Although we get quick energy from simple sugars, it doesn’t last long, and we feel hungry soon afterward. People with diabetes will recognize that the measure of glucose in blood rises almost immediately after they eat simple sugar but comes down pretty fast too.
Complex sugars consist of long chains of sugar molecules. Fiber and starch are the common terms for complex sugars, and examples include whole wheat, brown rice, beans, pulses, oats, fruits, nuts and vegetables. Complex sugars tend to fill you up for longer, and they are considered healthier because they contain more vitamins and minerals.
Healthier complex sugars become simpler sugars when fiber is taken out during food processing. Whole wheat flour becomes white flour, brown rice becomes white rice and whole oranges with tons of fiber become orange juice with zero fiber and 100% simple sugar that raises blood sugar very quickly.
The tool that measures how quickly different foods raise blood sugar is called the glycemic index. There is a range from zero to 100, with foods above 70 considered high, and foods below 55 considered low. Those foods with a high GI raise blood sugar faster, and foods with a GI below 55 raise blood sugar slower.
Here are two very important things to remember about the importance of carbohydrates.
1) Your brain requires carbohydrates, specifically glucose, because neurons cannot burn fat!
2) The United States Dietary Guidelines 2015-2020 recommends obtaining 45 to 65 percent of energy needs from carbohydrates, and a maximum of 10 percent should come from simple carbohydrates. To give you an idea of what that looks like, one can of pop has about 150 calories in it, leaving a 6-foot person that needs 2000 calories a day just 50 calories from simple sugars for the entire day to meet the very conservative guidelines from the US government. If that person puts sugar in their morning coffee, they are done for the day with simple sugars! If you are under six feet tall and only require 1500 calories a day like many people in Smith Center, that one can of pop is your daily allocation of simple sugar.
So, in terms of weight loss and health, what’s the action-oriented take away from this very basic lesson in organic chemistry?
First, carbohydrates are not bad but eat fewer simple carbs and more complex carbs. Eliminate as much pop and foods high in simple sugars as you can and increase complex carbs that have fiber in them.
Second, eat more fiber, that’s what makes a simple carb a complex carb. Remember that fruit juice is no better than pop; it is a highly processed simple sugar with zero fiber! Dietary guidelines suggest no less than 25-30 grams of fiber a day. The University of California San Francisco says that average Americans get fewer than 15 grams of fiber a day.
Third, reduce or eliminate processed food. Processing is a triple whammy. It removes fiber and increases both simple sugar and fat.
Fourth, especially if you are the one in 10 Americans that have diabetes or the one in three Americans that are prediabetic, you may want to start paying attention to the glycemic index. (https://www.gisymbol.com/about-glycemic-index) Be careful with foods that are above 70 on the glycemic index and consume more foods that have a GI of below 55. If you have diabetes and still eating processed breakfast cereals, white rice, instant oatmeal and French fries, you might want to consider eating foods with more fiber that are lower on the glycemic index.
Next week we’ll look at low-carb diets. Until then, make it a healthy week!
Here are the references for today’s Healthy Eating Tip:
All of the nutrition and organic chemistry information in this healthy eating tip can be found in any well-written textbook. Please email me if you are interested in background reading on these subjects.
Glycemic Index Foundation. About Glycemic Index. What is GI? https://www.gisymbol.com/about-glycemic-index. (Accessed 8/19/2020.)
Centers for Disease Control and Prevention. Diabetes. Resources and Publications. Features and Spotlights. National Diabetes Statistics Report, 2020. https://www.cdc.gov/diabetes/library/features/diabetes-stat-report.html. (Accessed 8/20/2020.)