Carbohydrates: A Complex Subject Made Simple


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While there are many hotly debated nutrition topics, few evoke as much passion and interest as carbohydrates (aka carbs). Popular low-carb diets like Zone, Atkins, South Beach, and Paleo limit the intake of carbs, while others like the Ornish diet call for high carbs as the path to optimal health.

Who is right? Are carbs evil? What are carbohydrates anyways?

While carbohydrates can be a very confusing subject, the following will break down all the important concepts, definitions, and topics related to carbohydrates to turn a complex subject into a simple one. Future articles will expand and explore each concept in more detail.

What are Carbohydrates?

Carbohydrates are found in foods including fruits, vegetables, grains, potatoes, pastries, and candy and are considered the bodies preferred energy source. More specifically, carbs are sugar molecules that are a union of carbon, hydrogen, and oxygen (CHO). Think of carbs as one, or more sugar molecules that are binded together and broken down by the body to be used as fuel.

Here’s a quick list of carbohydrates for your reference:

Types of Carbohydrates

Carbohydates are classified in many different ways:

  • healthy vs. unhealthy
  • good vs. bad
  • slow vs. fast
  • simple vs. complex
  • No wonder people get so confused!

    Remember, carbohydrates are just sugar molecules, all of which are broken down by the body into glucose. Glucose is a single sugar molecule that is used as fuel by the cells in your body from your brain to your muscles.

    There are 3 types of carbohydrates that are defined by the number of sugar molecules they contain:

    1) Monosaccharide - one sugar molecule, examples include glucose, galactose (in milk), and fructose (in fruit)

    2) Disaccharide – two sugar molecules, examples include sucrose (table sugar), lactose (in milk), and maltose (in beer).

    3) Polysaccharide – several sugar molecules, examples include starchy foods like pasta, or potatoes, and fiber, which is the indigestible part of a plant that aids in digestion.

    When a carbohydrate is “simple” it refers to mono & disaccharides that are easily absorbed into the bloodstream because of their simple molecular structure. Think milk, fruit, and table sugar. “Complex” carbs on the other hand are polysaccharides and because of their more complex molecular structure can take longer for the body to break down into sugar. Think grains, vegetables, and potatoes.

    You may be thinking, “Ok, so simple carbs are bad and complex carbs are good, right?” The answer is not that simple as you’ll learn in a moment.

    Function of Carbohydrates

    Before digging deeper to understand what carbs to eat, we need to understand how carbohydrates are used and stored in the body.

    As carbohydrates are broken down and enter the bloodstream, they increase the amount of sugar (glucose) in the bloodstream. The level of sugar in the bloodstream is called your blood sugar level. As you eat carbs, your blood sugar level rises, which activates the hormone insulin to suck the excess sugar out of the bloodstream and into your muscles (which can absorb about 300-400 grams) and your liver (which can absorb 100 grams).

    What happens if your sugar storage tanks (muscle & liver) are full and you keep on eating carbs? Any excess glucose that is not used by the body for energy will be stored as fat. The more “insulin sensitive” your muscles are, the more readily they will suck in sugar instead of having that sugar get converted to fat. And what’s a great way to make your muscles more insulin sensitive? Strength training of course!

    Good Vs. Bad Carbohydrates

    Many nutritionists do not use the word “bad” when describing food because as the saying goes, “there are no good, or bad foods, only good, or bad diets”. With that said, carbohydrates that cause your blood sugar level to rise rapidly are generally considered bad, or unhealthy carbs whereas those that are absorbed slowly and have little effect on blood sugar levels are considered good, or healthy carbs.

    The Glycemic Index was created to measure the speed with which carbohydrates are converted to glucose. Foods that digest quickly are high on the index, which ranges from 0 to 100, and foods that digest slowly 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 if levels are chronically elevated from over consumption of fast digesting carbohydrates.

    Here’s a short list of some high and low glycemic carbohydrate foods:

    While the Glycemic Index can be helpful, it’s not perfect. For example, some ice cream can show up as 30 on the glycemic index, along with some other carbohydrate sources like spaghetti that are nutritionally anemic and provide substantial calories in small servings. In addition, foods like watermelon that are high on the Glycemic Index impact blood sugar levels far less when adjusted on a per serving basis (watermelon is mostly water, hence the name). This concept is referred to as the Glycemic Load. Lastly, when combining the carbohydrates with different foods like dietary fat, the pace of digestion can slow down.

    Confused? Don’t be. If you are eating whole, natural, unprocessed carbohydrates, you can consider them a good carb, but if the carb was made in a lab, or has been processed such as soda, candy, or white bread, it’s a “bad” carb, or better yet – not ideal. I don’t like using the bad word unless describing High Fructose Corn Syrup, which is a chemically altered sugar found in tons of foods we eat every day. More on HFCS another time!

    Do Bad Carbs Make You Fat?

    I wish I could answer this question easily, but even an experienced researcher with a PHD would cringe at the thought of a proper answer.

    There are two primary camps that attempt to describe how we gain and lose fat:

    1) Energy Balance Theory – If you eat more calories than you burn, and you gain weight and if you eat less calories than you burn, you lose weight. This theory is based on the law of thermodynamics where energy can neither be created nor destroyed. You can eat as many carbs as you like and as long as you eat less total calories than you burn, you will lose weight. Harvard Medical School, The Institute of Medicine, along with most large and reputable organizations support this theory.

    2) Carbohydrate Hypothesis - Carbs, not calories make you fat is the summation of the carbohydrate hypothesis. Proponents include Dr. Robert Atkins, Dr. Michael Eades, and other medical and nutrition experts who view carbs as the root cause of the obesity epidemic. As long as you sufficiently decrease your carb intake, you will lose weight.

    Who’s right? Well that’s worthy of a separate blog post for sure, maybe even a book, but my best guess is the truth lies somewhere in the middle; eating less calories helps you lose weight, but eating too many carbs and not enough protein may have you gaining fat, and possibly even losing muscle. Furthermore, genetics, hormones, and activity level play a huge role in how easily carbs are stored, used as energy, or converted into fat.

    Eating some candy, or cookies here and there will not make you fat, but eating a lot of fast digesting carbs combined with excess calories and no exercise is a great strategy for adding a bunch of body fat.

    So How Many Carbs Should You Eat?

    This question will also be explored in more detail in a separate post, but here’s the short scoop:

    The amount of carbohydrates you should eat depends primarily on your genetics, body size, and activity level. If you are a 180lb sedentary guy who wants to maintain weight with a few workouts per week, a good benchmark for carb intake is around 200 grams of carbs. The more active you are, the more carbs you can add. Endurance athletes can and should eat around 300-400 grams per day to help fuel their workouts. The minimum RDA (Recommended Dietary Allowance) for carbs is 130 grams, with 55% of total calories coming from carbs as the general recommendation.

    From an evolutionary standpoint, carbohydrates are not essential, which means we do not need to consume carbs in order to function. In fact, if you eat no carbs at all, your body will break down body fat into small molecules called ketones. Ketosis is this process of creating ketones when our body uses primarily fat for energy, which is associated with a carb intake of under 25 grams (under 100 grams is when ketones are first present in the bloodstream and urine). Our bodies not only use fat for energy during ketosis, but may also convert protein (both dietary and muscle) into carbs to be used as fuel.

    You may be thinking – “I need to get into a state of ketosis immediately” given the apparent fat burning potential. While ketosis is a cool adaptation, it may leave you with low energy levels, really bad breath, inability to concentrate as effectively, along with serious vitamin and mineral deficiencies. Furthermore, research studies do not show fat loss is any greater during ketosis versus a diet of equal calories with a lot more carbs. Why be miserable and have the same pace of fat loss?

    When it comes to carbs, use your common sense – a few servings of fruit, plenty of veggies (which provide few calories but tons of nutrients), some starch/grains (or a lot if you are very active) each day should help fuel your body and provide the essential nutrients it needs to function optimally.

    Reference of Carbohydrate Terms

    Carbohydrate – sugar molecules that are a union of carbon, hydrogen, and oxygen (CHO) and are broken down by the body to be used as fuel. One sugar molecule is a monosaccharide, two is a disaccharide, and more than 10 is a polysaccharide.

    Glucose – A monosaccharide found in plant and animal tissues, which is transported by the blood to all the cells of the body to be used for energy.

    Glycogen – A polysaccharide that is the main form of carbohydrate storage in animals and occurs mainly in liver and muscle tissue; it is readily converted to glucose and glucose is converted into glycogen.

    Glycemic Index – an index ranging from 0 to 100 indicating the effects of various foods on blood sugar. Fast-releasing foods that raise blood sugar levels quickly are high on the index, while slow-releasing foods, at the bottom of the index, give a slow but sustained release of sugar

    Gylcemic Load – an index indicating the amount of carbohydrate contained in a specified serving of a particular food. It is calculated by multiplying the food’s glycemic index by its carbohydrate content in grams and then dividing by 100.

    Blood Sugar Level – The concentration of glucose in the blood, measured in milligrams of glucose per 100 milliliters of blood. The normal fasting value is between 3.9 and 5.6 mmol/l.

    Ketosis – the abnormal accumulation of ketones in the body as a result of excessive breakdown of fats caused by a deficiency, or inadequate use of carbohydrates

    Insulin – A hormone secreted by the pancreas in response to high blood sugar levels. Insulin regulates the body’s use of glucose and the levels of glucose in the blood by acting to open the cells so that they can intake glucose

    Glucagon – a hormone secreted by the pancreas that acts in opposition to insulin (raises concentration of sugar) in the regulation of blood glucose levels.

    Fiber – a type of carbohydrate that is coarse, indigestible plant matter that when eaten can help improve digestion.

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    30 Comments on “Carbohydrates: A Complex Subject Made Simple

    1. Shannon
      May 18, 2012 #

      Hi Marc

      Interesting, but not enough information I think. After having read Dan Bernardot’s Advanced Sports Nutrition, I have a much better understanding of carbs and their function, and I have changed my approach to them completely. You don’t mention anything about the timing and quality of carbs–ie that it is beneficial to consume simple carbs just prior to training, during and immediately after (together with protein) to make sure that the blood sugar levels are maximized for the duration of training and recovery. Do you go into more detail on this in your program, or?

      Thanks, Shannon

      1. Ray
        May 19, 2012 #

        I think the point was to simplify this often confusing topic for the majority of people. While that information sounds great, It might have been counter productive to the article.

      2. May 20, 2012 #

        Hey Shannon – Yes, there certainly have been entire books written about carbs and I could have easily made this article into a 5,000 word article, but I only included what I felt was necessary as an introduction.

        The one thing I did not include which I will add is the concept of satiety and fast digesting carbohydrates. Will add a sentence in there in the next couple days. I could have discussed various hormones like leptin etc. and a host of other topics related to carbs, but again, I think it’s too much. For more on pre/post workout nutrition, check out this article – http://www.builtlean.com/2012/01/24/pre-workout-meal/. I agree with Ray that if I included much more info, it would have taken away from the article. The info I have in my program goes into more depth about carbohydrate intake and how it relates more to fat loss from a hormonal perspective, but it’s not too deep. I don’t want BuiltLean to be targeted for PHD’s and fitness professionals, just for people who want to improve their health and well-being and get solid information! Thank you for your comment.

    2. Tom
      May 18, 2012 #

      Hi Marc,

      This is one of your must important articles. I have found the subject of carbs very confusing. I agree with you that it can be simplified and you have done a great job. I think with a little study on my part I can find the right foods that work for me to keep my weight healthy without loosing muscle. I need to understand the difference between glycemic index and glycemic load.

      Which is more important to follow in the tables of GI and GL?

      Thanks

      1. May 20, 2012 #

        I think the glycemic index is generally more helpful. There are only a handful of foods anyways that have a major difference between their GI Index and the Glycemic load. I think all fruits and veggies should be fine. Remember generally speaking, if man made it, don’t eat it. The less processed the carbohydrate, the better. FYI, I don’t eat cold cereal anymore because most are just too processed. Don’t think it’s necessary. I look forward to adding more snack/meal ideas along with solid carbohydrate sources.

    3. Mona
      May 18, 2012 #

      tanX Marc

      you answered my Question before I ask it ! but i have anothers too , Does Eating Bananas Cause Belly Fat – be coz of the Carbohydrate and the Glycemic ? what about spiking insulin ?

      another thing is that, I’v heard that Honey, which is a type of simple carbohydrate, can increase glucose and insulin such as cane syrup, that will effect on blood sugar level, is it true ?

      1. May 24, 2012 #

        @Mona – Eating bananas does not necessarily cause belly fat. It’s more of a calorie issue than a carb issue. Not sure you’ve hear, but there are even diets like the banana diet that help people lose weight (not such a smart diet, but it can work as long as calories are decreased). If you are particularly sensative to carbs, yet bananas can spike your insulin. Any sugary substance can increase insulin secretion because it makes your blood sugar levels rise.

    4. Zalaba
      May 18, 2012 #

      You guys can do much more research on carbs…As i know,all carbs can be used for fat loss…low carb day-vegetables…on maintanance day-u add some yams,oats…and on cheat day-add some juice,something you like….carb cycle!

      1. May 20, 2012 #

        @Zalaba – thanks for sharing your input. This is meant to be an introductory article and FYI, there is no scientific proof carb cycling improves fat loss, it may actually be decreased calorie intake from the decrease carb intake that causes the fat loss.

    5. Jairo Molina
      May 18, 2012 #

      Great Marc, it is a complex subject and the article is a good starting point for everyone interested in learning about carbs. Does the Weight Watchers program use the glycemic index as a way of scoring points ? Thanks.

      1. May 20, 2012 #

        Hey Jairo – to my knowledge weight watchers simply count calories/carbs/protein/fat and does not differentiate between the different carbs. Nutrisystem is based on low GI carbs as well as a number of other diets and food delivery services.

        From weight watcher’s website –

        “With Weight Watchers, every food has a PointsPlus value, which takes into account a food’s protein, carbs, fat, and fiber. Using advancements in nutritional science, we’ve developed a formula that helps us wrap it all up into one easy-to-use, number. You’ll get a daily personalized PointsPlus Target, so you know how much to eat to lose weight safely?while feeling satisfied.”

        I’m not a big fan of weight watchers unless for those people who are very obese. Why not learn about food and how it affects our body instead of reducing eating to a point system? That’s my take!

    6. Peter
      May 19, 2012 #

      It’s not just the US where this is a problem – it’s really bad here in Australia as well. In fact I read recently that Australia is now officially the most obese of all OECD countries. I was in that ‘o’ category a year ago. Heading for an early grave, I’m sure. Then I decided to change things – as a 58 year old male ‘addicted’ to high sugar convenience foods, it hasn’t been easy but IT CAN BE DONE. I dropped 50 pounds in weight and all my vital readings are now in the ‘normal’ zone. So if there are any doubters out there – I hope my story helps you get started. My weight has been stable for 6 months and I am enjoying life to the full. Check out http://www.fitbit.com/user/22423T.

    7. Peter
      May 19, 2012 #

      Sorry, Marc, I meant 60 lbs – anyway – I wish I had found your site a year ago so I could have understood more about the journey i was starting. Based on my own research and readings in the last year or so, it is really refreshing to find a young fellow offering sound advice based on Fact rather than trying to sell some wonder, miracle ‘weight loss’ program. There is no substitute for hard work and dedication. No wonder you wear a smile so well. Now – can 60 year old guys get ripped?

      1. May 20, 2012 #

        Thanks a lot Peter for your kind words. I’m very happy to hear your journey is going well. I think it’s possible for a 60 year old to get ripped, but I think “lean” is a better word. Getting lean is something that is sustainable and healthy whereas i think getting ripped is something that generally ephemeral, even for a fitness model. Fitness can be a slippery slope; the difference between working out hard and eating well vs. working out like crazy and being too strict with your diet, which is what is necessary to get ripped. If you want to do it as a hobby, or for kicks, that’s cool!

    8. May 19, 2012 #

      Very difficult subject that is presented cogently. What about the amount of carbs vsersus age? You mention 300=400 for an endurance athlete but what about the change in amount for a normal person with 2 workouts a week who is over 60? Are there charts that exist based on age?

      1. May 20, 2012 #

        That’s a great question. I think the concept of carbohydrate intake based on age and activity level is a great one and worthy of exploration. In fact, I think some type of online calculator could be very cool. My guess is someone ho is 60, somewhere around 150 grams of carbs could work well. It’s enough to fuel your body functions and your workouts without providing any more than you need.

    9. Borys
      May 24, 2012 #

      Dear Marc,

      first of all, I would like to congratulate you on this terrific website. The ressources you have offered so far and the benefits you lay out of living a healthy lifestyle are so motivational and easily comprehensible that anybody reading this site just must feel compelled to drop his bad eating and living habits. I’d like to tell you, that especially your article about the afterburn-effect regarding total calorieburn is so enlightning, it just gives you motivation to “bring it” in the gym, as Tony Horton would say. Burning during and after exercise, that’s a two-for-one-deal! Great job of keeping the eyes on the prize, creating a mind-set, that simply makes intense workout seem and actually be fun.

      But before I drown you in accolades, I’ll pose my question and I hope it fits the topic of the article at least somewhat:

      Is drinking Coke Zero advisable while trying to stay in shape/drop a few pounds? It has 0 carbs, 0 calories and I wonder if one is allowed this treat. There are quite a few urban myths about rising insuline-level, I can’t buy and I don’t feel like disparaging this drink, considering how good it tastes. There might be some health risks involved with consuming Coke Zero, but I have not found anything convincing so far, except for unfounded negative prejudice. Having a glass of Coke to get a taste of sweetness would make mainting a diet a lot easier, because people could get the sweet taste they crave every once in a while, avoiding a potential outburst of hunger for sweets with potential devastating effects on the work put in beforehand. I am looking forward for your answer.
      Thanks a lot for everything so far!

      p.s.. This question could be made into an article, by the way. I believe many people might be interested in it. There is so much material on Coke Zero, that could be presented concisely and you have proven time and again that you’re great at delivering the hard facts enabling sound decision-making on how to proceed, in order to remain/become fit and healthy!

      1. May 26, 2012 #

        @Broys – Thank you for the kind words regarding the BuiltLean website!

        My take on Coke Zero is that yes, it’s better than regular coke, and even diet coke. And yes, if it can help you stay on track with a healthy diet by providing a sugary taste, I’m a realist and understand that can be fine too.

        With that said, we are meant to drink water as our primary source of hydration. Other ideas can also include herbal teas. Also could add a squeeze of real fruit to water as well for some added taste.

        Coke Zero while it provides no calories does have some ingredients: “Carbonated water, colour (caramel E150d), phosphoric acid, sweeteners (aspartame, acesulfame-K), flavourings (including caffeine), acidity regulator (E331). Contains a source of phenylalanine.”

        I’m not a huge fan of drinking chemicals that I can barely pronounce. I have no desire to drinks coke for the aforementioned reasons, nor do I recommend it.

        I agree with you that this topic is certainly worthy of a separate post and we’ll get to that for sure. Hope this answer is satisfactory without getting into too much depth and making this comment a separate article!

    10. anthony
      June 4, 2012 #

      Hi marc.

      im currently 145ibs at 5’11.. People tell me I dont eat, I eat all the goddamn time imo!.. However I have been sedentary for a while due to depression (family grievance) and when I was training I was scraping just under 160 on a 2600 cal diet, strength training 3 times a week and conditioning drills, and sprint drills. I was 10% bodyfat and people said I looked good, but I still felt underweight. Im not into bodybuilding, tried it, wasnt for me, I moved on. I did boxing when I was younger so many of my training methods resemble that I guess. I would “like to be around 190, but not have to struggle to maintain weight.. If I incorporate squats and deadlifts 3 times a week, and up calories to 3500/4000, while doing boxing style training and also judo which I want to take up, can I achieve this? Like if I did little or no distance running, and more sprint stuff for running? Also where should my testosterone be around for my age?

      thanks.

      1. June 7, 2012 #

        @anthony – My guess is somewhere around 160-170 is a solid weight for someone your height (I’m 5’11” as well). 190lb sounds very high, unless you are naturally built like a truck (think professional football players). Very few guys have over 165lb LBM at 5’11” and thats assuming many, many years in the gym. In fact, the average is 145lb. Assuming you get to 145lb LBM, that would mean you would have 12% body fat at a weight of 165lb.

    11. anthony
      June 4, 2012 #

      I forgot to mention im 24 :)

    12. anthony
      June 8, 2012 #

      So should that be my normal weight? Or training weight? Am I currently underweight then?

      I have calipers that seem to indicate my bf is very low even sedentary.. (Thigh and abdomen come up as 10%, chest is about 5).. Is their a good chance I am suffering from something? Youd think id be in the 20% range if im inactive.. How many calories should I be getting a day regardless of activity? If I have to eat extra calories just to be at anormal weight is something wrong with me? (hope that makes sense)
      its just im a bit worried, as people tell me I look ill,..

    13. June 11, 2012 #

      @anthony – it sounds like you should schedule an appointment with your doctor would make sense.

    14. anthony
      June 13, 2012 #

      Its just my doctor tells me my weight is fine, yet many people disagree.
      im an ectomorph, but having said that, my normal sedentary weight used to be about 150.
      is their any chance you could possibly just tell me how to correctly use the calipers, as im finding contrary information. I dont even know how much skin to take into the fold.

      also what is your weight roughly? Just as a rough guide for me to aim for..

      1. June 14, 2012 #

        @anthony – My weight is 170lb and I’m 5’11″ and my body fat is around 7%. I would suggest going to the manufacturer of the calipers and getting a manual from them, but I do agree with you I should have a post on how to measure your body fat with skin fold calipers. The idea is you want to make the space between your index finger and thumb and inch wide, pull the skin and fat clearly off the muscle, then measure the space about a centimeter from your thumb.

    15. Stacy
      June 27, 2012 #

      Quick question on nutrition….

      My stats: 135lbs, 5’6
      My daily macros: 1360 cals / 135 protein / 100 carbs / 45 fat
      Exercises 4 to 5 times a week: includes cardio, and strength training for muscle building…all exercise at a moderately high to high intensity each workout.

      I stay really close to the my macros each day. I am not sure if 100 carbs is enough, though…especially after reading about ketosis in this article. I only eat the bulk of my carbs breakfast and post-workout. I have noticed that I do not retain as much water…which is a plus, but no weight loss at all after 4 weeks of this carb decrease and timing change.

      In your opinion, do I need more calories? Also, do I need more carbs? I read in some articles that 100g of carbs is needed just to maintain body functions, so maybe I am defeating my efforts by not eating enough carbs to supply my workouts. Not sure. My goals are to build lean muscle, decrease fat and overall be healthy.

      Any advice is appreciated.

      Thanks for you advice.

      P.S. I sent this in an email previously, but thought I would post here instead.

      1. July 2, 2012 #

        @Stacy – I apologize for the delay in my response. Typically under 50 grams is when ketosis really kicks in, so in my mind 100 grams is likely fine. If you were a 180lb man, I would say it may be a little low. Generally speaking, I actually recommend taking calories even lower, rather than increasing. In my Weight Loss Plateau: Tips on How to Break It article, I talked about the calorie creep. While this may not be happening to you, a 1200 calorie diet I’ve found to be the sweet spot for many women. I’ve also found people in general vastly overestimate calorie burn, not that you are. The reality is that losing fat especially as you get leaner is not extremely pleasant. I would definitely read that article closely and see if it helps.

    16. Stacy
      July 3, 2012 #

      Thanks Marc. I will check out the article you mentioned.

      Have a great day!

    17. Donald
      August 20, 2012 #

      Mark,

      first off congratulations on the best fitness website in the world I think you have probably helped thousands of people with their health which is the most important thing a person could have. on behalf of the human race I would like to say well done.

      One thing im confused with is the subject of fruit obviously you should eat it but at the beginning of your article you said that because fruits have simple Monosaccharide sugars they quickly enter the bloodstream which is a bad thing. however they are low on the glycemic index which would suggest the opposite. could you clear this up please?

      1. August 23, 2012 #

        @Donald – Thanks, Donald for your very nice comment! Fruits are absolutely ok to eat in moderation and some are higher on the glycemic index than others. In fact, a grapefruit for example is only a 25 on the glycemic index. My favorite type of fruits for fat loss is watery fruits like grapefruit, orange, and an apple, or berries like strawberries, and blueberries.

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