Three of the four macronutrients play critical roles in the healthy and proper functioning of the human body. Their roles in a keto lifestyle remain very important, however, the consumption amounts of each differ from standardized recommendations from the government and general consensus found currently in most health and nutritional documentation. Understanding the importance and role of each macronutrient provides insight into a responsible integration and adaptation to meet the goals and principles of keto or low carb living. In this article I will provide a detailed look into the macronutrient of Carbohydrates. This is Part 2 of a 5 part series on Understanding Macronutrients. Check out the rest of the series for a complete understanding of all the macros.


Carbohydrates are basically carbon-based substances that contain water and are a type of macronutrient found in many foods and beverages. Dietary carbohydrates are broken down into glucose and other monosaccharides rapidly supplying energy to the body. Although most carbs occur naturally in plant based foods, such as grains, they are also added to processed foods by food manufactures in the form of starch or added sugar. The three main types of carbohydrates are sugar, starch and fiber.


Carbohydrates are considered to be either simple or complex. The difference between these two forms is their chemical structure and how quickly the sugar is absorbed and digested. Simple carbohydrates consist of small molecules which rapidly increase blood glucose levels. These types of carbs can lead to very rapid spikes in blood sugar levels and consequently insulin. They contain just one (monosaccharide) or two (disaccharide) sugars such as fructose (found in fruits), galactose (found in milk products), sucrose (table sugar), lactose (from dairy), and maltose (found in beer and some vegetables). The simple carbs found in candy, sugar and syrups are made with processed and refined sugars and are considered “empty calories” due to their lack of vitamins, minerals or fiber. Complex carbs consist of additional molecules and are known as polysaccharides. These types of carbs are broken down into monosaccharides increasing blood glucose levels more slowly subsequently lasting longer and providing more sustained energy. Starches and fiber are complex carbohydrates and are often found in fruits, vegetables, whole grains, beans and peas. (1,2)


Different foods impact the rate that glucose levels rise primarily because of these different types of carbohydrates. The glycemic index (GI) measures how quickly blood glucose levels rise based on the specific food consumed. The GI value is simply measured by measuring the effects of digestible carbohydrates on people’s blood glucose levels over a specified amount of time. The GI has proven to be a useful nutritional analysis allowing new insights into the relation between the physiological effects of carbohydrate-rich food, glycemic load and health. The glycemic load (GI) takes into account the total amount of carbohydrates in a food providing even more insight into the impacts of specific food on blood sugar levels. Some studies have shown that the chronic consumption of a diet with a high glycemic load (GI x total dietary carbohydrate content per serving / 100) is independently associated with an increased risk of developing type 2 diabetes, cardiovascular disease, and certain cancers. Generally speaking, if you consume carbohydrates it is recommended you eat those with lower GL and GI values. (3)

The glycemic index uses a value of 1 (the slowest to increase glucose levels) to 100 (the fastest to increase glucose levels). Both the quantity and quality (nature of the source) of the carbohydrate influences the glycemic response. Glycemic Index values are generally categorized as low (good), medium, and high (bad).

  • 55 or less = Low (good)
  • 56-69 = Medium
  • 70 or higher = High (bad)

Determining the glycemic load requires multiplying the total carbohydrate content per serving by the GI and then dividing by 100. It provides an even more accurate assessment of the impacts of food on blood sugar levels. GL is also generally categorized as low (good), medium, and high (bad).

  • 0-10: Low (good)
  • 11-19: Medium
  • 20 or higher = High (bad)

There are no GI values given for meat, poultry, fish, avocados, salad vegetables, cheese, or eggs because these foods contain little or no carbohydrates. GI values can vary for the same food based on measurement techniques, where the food was produced, how the food was produced and specific brands. Table 1 below shows the average GI of 62 common foods derived from multiple studies by different laboratories. (4)


Table 1 (4)


Fiber is an important type of carbohydrate that has several key health benefits. Unlike most carbohydrates, fiber is not broken down into sugar molecules but instead passes through the body undigested with minimal effects on glucose levels in your blood. Soluble and insoluble are the two types of fiber. Soluble fiber, which dissolves in water, can help lower glucose levels as well as help lower blood cholesterol. Foods that contain soluble fibers include oatmeal, nuts, beans, lentils, apples and blueberries. Insoluble fiber, which does not dissolve in water and remains intact, can help food move through your digestive system keeping someone regular and preventing constipation. Foods that contain insoluble fiber include wheat, whole wheat bread, whole grain couscous, brown rice, legumes, carrots, cucumbers and tomatoes. Recommended amounts of daily fiber intake are:

  • Men age 50 or younger: 38 grams
  • Women age 50 or younger: 25 grams
  • Men age 51 or older: 30 grams
  • Women age 51 or older: 21 grams

Numerous studies suggest that fiber can reduce the risk of various diseases and conditions to include heart disease, type 2 diabetes, diverticular disease, colon cancer and breast cancer. Including an adequate amount of fiber in your diet is generally considered a healthy and recommended choice. It is important to consider this when starting a low carb or keto way of eating because often times fiber consumption decreases too much because of a narrow focus on reducing all carbohydrates. (5,6)


The U.S. Dietary Guidelines recommend that carbohydrates should be 45-65% of total caloric intake which equals on average approximately 130 grams. The guidelines advise that less than 10% of calories should consist of sugar. The World Health Organization (WHO) recommends that at least 55% of total energy come from a variety of carbohydrates for all ages except children under the age of 2 years. The WHO’s most recent guidelines from 2015 now recommend that sugar should only be 5% of your daily calorie intake, a drop from 10% in previous reports. For an adult of a normal body mass index that equals about 6 teaspoons, or 25 grams, of sugar per day. The American Heart Association recommends that no more than 100 calories (6 teaspoons) of sugar per day for women and no more than 150 calories for men (9 teaspoons). The health risks of sugar intake are well documented and often directly attributable to a growing obesity and diabetic outbreak both in the United States and worldwide. If you are going to eat carbohydrates avoid sugars, specifically those that are made up of simple carbs. (7,8,9)


The fundamental component of the ketogenic lifestyle is to avoid carbs, however, there is one exception. We can’t forget about the importance of fiber as part of our diets and as discussed above fiber is a type of carbohydrate – the “good” carbohydrate. A better way to phrase the fundamental component of the keto lifestyle is to avoid raising glucose levels in your blood based upon the foods you choose to eat. Fiber does not raise glucose levels, in fact can lower them, and is important of overall health. This is the reason that many people on keto only count net carbs (total carbs – fiber) because fiber is widely accepted not to increase blood sugar levels. Those that suggest total carbs should be counted are often concerned that soluble fiber can increase glucose levels. However, recent research suggests that both soluble and insoluble fiber help to lower glucose levels in the blood. This is due to the metabolic benefits of short-chain fatty acids (SCFAs) that are produced in the gut by the fermentation of soluble fiber. Despite this recent research there is still much to be learned about the impacts of soluble fiber on our metabolic processes. Whether you count total or net carbs is a personal choice, however, generally counting net carbs is a sound approach and it allows you to get more adequate amounts of fiber from low carb fruits and vegetables while your body “should” stay in ketosis. (10)

Peoples’ bodies react differently to carbs and those that are very carb sensitive can see significant spikes in blood sugar levels even with a small amount of dietary carb intake. Insulin sensitivity can also vary between individuals. The “I” for “Individualized” in my “RIPD” approach to a healthy lifestyle research certainly applies here because of the ways that carbs can impact each of us differently. The time of day you eat, what else you eat along with carbs, genetics, weight, overall health and what your activity levels are all influence the personal glucose raising effects of carbohydrates. And to make it even more complex, don’t forget about the glycemic index and load of different carb-rich foods and how that also influences blood glucose levels. With a better understanding of these variables it is not difficult to realize why people can enjoy the benefits of low carb and even stay in ketosis by eating different amounts of the right carbs. 

The definition of “low-carb” diets vary and can generally range from 20 grams to 125 grams of dietary carbohydrate intake. Dr. Volek and Phinney provide a simple explanation of low carb as “that level of carbohydrate intake below which your signs and symptoms of carbohydrate intolerance resolve.” Because let’s be honest, you don’t have to be on “keto” to experience the plethora of health benefits, including easier weight loss, of a generally low carb lifestyle. Keto provides additional benefits but a low carb lifestyle is much better than one with moderate or higher amounts of dietary carbs.

There are also variations on the amount of recommended dietary carbs that should be consumed in order to transition into and maintain nutritional ketosis. The physiological shift from glucose to fat as the body’s primary fuel source begins for most adults when total carbohydrates are restricted to less than 60 grams per day along with a moderate intake of protein. At 60 grams of carbs per day, the average person’s ketone level is nearly 10 times higher than someone consuming 300 grams of carbohydrates. A general consensus within the keto community and supported by research is that 20-30 grams of net carbs is ideal for achieving and maintaining nutritional ketosis. When converting these numbers of grams, net carbs come out to approximately 5% of total caloric intake. For example, 5% of 2000 calories is 25 grams (100 calories).  Once a person is ketogenic for a period of time, increases in net and total carbs may be achievable while maintaining ketosis. Remember the “I” in “RIPD” applies here because it truly takes personal experimentation and individual experience to determine what works best for each person. Anyone who claims otherwise doesn’t fully understand the science and the variables in play to achieve and maintain ketosis. (11,12)


I transitioned to and have maintained ketosis for nearly a year with a target of 25-30 grams daily of net carbs. I do not shy away from eating low carb vegetables and fruit because the fiber, nutrients, antioxidants and vitamins are extremely important to good overall health. I believe the keto lifestyle is optimally performed when it is well balanced to include fruits and vegetables. The primary fruits I eat are berries (raspberries, blueberries, blackberries, strawberries) which I have each morning with my breakfast and often as part of my lunch. The primary vegetables I eat are lettuce (and spring mixes), cucumbers, bell peppers, celery, zucchini and broccoli. I also found that including low-calorie, high-fiber foods increases satiation and results in less desires to want to snack between meals. I strongly disagree with anyone who categorizes keto (or low carb) as a “meat and cheese” or “fat only” way of eating. If you do it right, you should be eating just as much or more fruits and vegetables as you did before going lower carb – you just need to know which kind to eat. I highly encourage my clients to incorporate fiber on day one of starting the keto way of eating. As a bonus, I cook almost everything I can in butter – buttered vegetables are a perfect way to mix in fat and low carb green cruciferous vegetables with plenty of fiber.



  1. Nutrition and Healthy Eating; Carbohydrates: How carbs fit into a healthy diet, Mayo Clinic. http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/carbohydrates/art-20045705
  2. Szalay, What Are Carbohydrates?, LiveScience, 2017. https://www.livescience.com/51976-carbohydrates.html
  3. Powell, International table of glycemic inex and glycemic load values, The American Journal of Clinical Nutrition, 2002. http://ajcn.nutrition.org/content/76/1/5.full.pdf
  4. Diabetes Care. Table 1, 2008. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2584181/table/t1/
  5. Dietary fiber: Essential for a healthy diet, Mayo Clinic, 2015. http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/fiber/art-20043983?pg=1
  6. Fiber, The Nutrition Source, Harvard School of Public Health. https://www.hsph.harvard.edu/nutritionsource/carbohydrates/fiber/
  7. Table A7-1. Daily Nutritional Goals for Age-Sex Groups Based on Dietary Reference Intakes and Dietary Guidelines Recommendations, Dietary Guidelines for Americans 2015-2020 Eight Edition. https://health.gov/dietaryguidelines/2015/guidelines/appendix-7/
  8. Sugar 101, American Heart Association, 2017. http://www.heart.org/HEARTORG/HealthyLiving/HealthyEating/Nutrition/Sugar-101_UCM_306024_Article.jsp#.WdluGoVm3hM
  9. Guideline: Sugars intake for adults and children, World Health Organization, 2015. http://apps.who.int/iris/bitstream/10665/149782/1/9789241549028_eng.pdf?ua=1
  10. De Vadder, Microbiota-Generated Metabolites Promote Metabolic Benefits via Gut-Brain Neural Circuits, Cell, 2014. http://www.cell.com/cell/fulltext/S0092-8674(13)01550-X
  11. Volek, Phinney, The Art and Science of Low Carbohydrate Living, 2011.
  12. Wilson, Lowery, The Ketogenic Bible, 2017.



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