So what is sugar?Sugar is a carbohydrate, the primary source of energy for our body and especially our brain (yes I know the brain can use ketone bodies, but for the majority of us we are not eating a ketone diet.) Sugar can occur naturally in milk, fruit, vegetables, starches and grains, but can also be added to foods and drinks for flavour, or as a sweetener. Strictly speaking, carbs are not essential for life, however they have many benefits ranging from, energy, muscle recovery and growth, 'optimising' our hormones, metabolism and the immune system, satiety and taste great.
3 types of carbs exist1. Monosaccharides (simple sugars) and Disaccharides Mono meaning 1 molecule and these comprise of glucose, fructose and galactose. Di meaning 2 like sucrose, table sugar, (fructose + glucose) or lactose (glucose + galactose) found in milk. 2. Oligosaccharides A small number, more than 2, monosaccharides connected found in plant based foods. 3. Polysaccharides Carbohydrate molecules composed of long chains of monosaccharide like starch found in complex carbohydrates. Many people seem to class carbs and sugar as separate identities but understand sugar is carbohydrate. Carbs are digested by the body to produce ultimately glucose, which can then be utilised for energy, or stored as glycogen or fat. When fructose is ingested either from naturally occurring sources such as fruit, which contains about half fructose, half glucose, or from processed refined sugars, like table granulated sugar, which is also approximately a 50/50 mix, it is metabolised in the liver. Where it is converted to glucose and released into the blood and ultimately used as energy, stored as glycogen or fat. Many fear fructose but it ONLY becomes a problem when you are eating into a CALORIE SURPLUS where you are depositing more fat than you are burning (lipogenesis, fat formation > lipolysis, fat breakdown) over a 24hr period. This is because fructose can easily be stored as fat around the liver and other organs when liver glycogen stores are maxed. This can ultimately lead to non-alcoholic fatty liver disease. Does this mean you should avoid fructose if looking to gain muscle in a calorie surplus? No, because it's very very difficult to consume adequate amounts of fructose if you are eating minimally processed whole foods, which everyone I hope knows they should be doing! Fructose is almost always present with glucose, just like high fructose corn syrup, HFCS, which is typically 55% fructose and 45% glucose, similar to sucrose (table sugar.) And even in fruit, where a typical apple has a total of around 13g of sugar with around 7g of these being fructose. So do not think that all the sugar present in your food is fructose! So whether you eat candy, potatoes or a banana ultimately the carbohydrate present in these foods will be metabolised to glucose, when eating an energy balanced or calorie deficit diet.
So are there good and bad sugars?No, not necessarily! Becoming unnecessarily overweight carrying high levels of body fat can be unhealthy, and this will come from a calories surplus, independent of the food we consume, and a lack of physical activity. What is important to realise, is what comes with the particular food, both from a nutritional and psychological aspect. If we compare jelly babies to a banana, they are both providing sugar, but the fruit will also contain fibre and micronutrients. So if you are mainly consuming jelly babies as your carbohydrate source, you aren't consuming a balanced diet getting sufficient macronutrients, micronutrient and fibre, so fruit wins this battle.
But fructose and HFCS makes us fat, right?To answer this question I would like to quote James Krieger: "It is true that too much fructose can be a problem, but too much of anything can often be a problem. When consumed in moderate amounts and from whole food sources, fructose is not a nutrient to be feared." (10) "The bottom line is that there is no valid reason for HFCS to be any different than sucrose in the way that it affects your body. They are both nearly identical in their composition, containing roughly half fructose and half glucose. They are both nearly identical in the way they are metabolized by your body. There is no practical difference between the two as far as your body is concerned. Now, I'm not saying that you should go out and consume all the HFCS that you want. The point is that there is nothing uniquely "bad" about HFCS compared to regular sugar. HFCS is not uniquely responsible for weight gain as some people would have you believe." (11) And research carried out in 2008: "The data presented indicated that HFCS is very similar to sucrose, being about 55% fructose and 45% glucose, and thus, not surprisingly, few metabolic differences were found comparing HFCS and sucrose." (12) "The topic of sugar and obesity is all over the news and media at the moment, and many people believe that eliminating sugar and especially fructose from our diets will cure the obesity epidemic. Now I am not here to answer if cutting all added sugar from our diet would result in no more overweight individuals, but for the mean time I direct you to my sugar myths article."
Carbohydrate sourcesCarb sources vary though from high/low sugar, glycemic index, glycemic load, micronutrients, fibre, satiety, gluten and wheat free etc etc. Glycemic Index (GI) The glycemic index describes a foods ability to increase blood sugar levels once consumed. Foods are normally compared to pure glucose or white bread which has the advantage of being a common staple of peoples diet. Therefore making it easier for people comparing foods and foods are ranked from 0-100. Carbs with high GI normally break down quickly during digestion and release glucose rapidly into the blood, such as cereal, cake and sports drinks. Where as carbs that digest more slowly, releasing glucose more gradually into the bloodstream, tend to have a low GI. These include green veggies, berries, oat and beans for example. The GI of a particular carb has been shown to be not very accurate and have certain limitations. This is due to us eating mixed meals, consisting of protein, carbs and fat along with the presence of fibre. The assigned GI ratings are based on that specific item being tested and only that specific item, in an overnight-fasted state which will ultimately effect the GI of a meal. Secondly, there is an overlap of previous meals/nutrients being absorbed and digested, further blunting the GI of a particular carbohydrate of a future meal. By adding protein, fat or fibre to a food, you automatically change its GI. (1,2) Therefore, that sweet potato that had a GI of 70, might suddenly drop to 50 when you added it with a ton of veggies.
So is a diet consisting of lower GI foods better for weight loss?Recent research (13) sought out to compare a high-glycemic index (65% on the glucose scale), high-carbohydrate diet (58% energy); a low-glycemic index (40%), high-carbohydrate diet; a high-glycemic index, low-carbohydrate diet (40% energy); and a low-glycemic index, low-carbohydrate diet. They concluded that ‘diets with low glycemic index of dietary carbohydrate, compared with high glycemic index of dietary carbohydrate, did not result in improvements in insulin sensitivity.' Which may sound odd as you would presume the lower GI foods to improve sensitivity. This emphasis the inconsistency and problem with selecting foods based GI. In my opinion people get a little too OCD and hung up on GI when assessing their diet. Certain foods start to get banned by people because the GI is too high, for example white potatoes or basmati rice. Behaviour like this can lead to looking at food as good or bad, creating a bad relationship with your diet. But if you were consuming plenty of fruits and vegetables the GI of foods is something you should not worry about. Carbs are better judged on the basis of degree processing and micronutrients. Glycemic Load (GL) The glycemic load takes into consideration the glycemic index of a food and the amount of carbohydrates the food contains. Insulin Index The insulin index measures the insulin response in the body to a specific food. Most high GI foods will have a high insulin index but this isn't always the case. For example, whey protein with hardly any carbohydrates and a low GI leads to very large rises insulin. Protein has been show to elicit an insulin response just like carbs. (3,4)
So does the GI and GL matter for body composition?Several experiments have been carried out to compare high GI diets with low GI diets looking at body composition, LDL levels, satiety and food intake. They concluded that the effects on health such as LDL levels, cholesterol and blood pressure was dependent on whether the individual started unhealthy or healthy. Low GI diets were observed to be good for your health if you're initially unhealthy, but showed no advantage over a high GI diet in healthy individuals. With regards to body composition and weight loss they found no difference between low/high GI diet in muscle retention or fat loss between groups. (5,6) Several experiments have been carried out to compare calorie diets made up solely of sugar compared to other carbs. A meta-analysis by Sievenpiper et al looked at the effect of fructose on body weight in controlled feeding. "Fructose does not seem to cause weight gain when it is substituted for other carbohydrates in diets providing similar calories. Excess calories modestly increased body weight, an effect that may be due to the extra calories rather than the fructose." (7) Surwit et al found that a "High intake of sucrose from a low fat, low kcal diet did not adversely affect weight loss or other metabolic indexes when compared to a low fat, low sugar diet." The diets were of the same calories, with high sugar diet having 43% of kcal's coming from sucrose, compared to the low sugar diet with 5% or less of kcal's from sugar. (8) It is, however, important to know though that everyone responds to carb sources differently and in a study by the American Journal of Clinical Nutrition they found variation in the glucose and insulin responses to the same foods. (9) This is especially important for individuals suffering from certain diseases and illnesses. When GI and GL may be important is for endurance athletes or someone that is training multi times during a 24hr period. This is to ensure the replenishment of glycogen (stored glucose) as quick as possible to aid with recovery and performance. An interesting experiment carried out by Cramer MJ et al. compared the rate of glycogen replenishment of sports supplements vs fast food of the same macro nutrient contents. What they found was there was no difference in the rate of glycogen replacement, 6.9 and 7.9 mmol per kg wet weight per hour for the supplement and fast food, respectively. Along with no difference in performance during subsequence activity. (15)
So what does this mean?Well it shows that there is not much difference between sports supplements like energy drinks, etc or fast food when it comes to a recovery and performance comparison. For someone taking part in very long endurance and ultra endurance events eating sufficient calories of carbs, fat and protein is far more important than source, for improved recovery and performance.
Putting it all togetherFor body composition it doesn't matter if a carb is classified as high or low GI, GL or it's insulin index, only the total amount of carbs in your diet matters and this is because carbs contain calories, 4 calories per gram to be precise. With respect to health, the source of carb is relevant especially in an already unhealthy individual. It's important to remember that in a healthy body there are many mechanisms in place to regulate blood glucose levels, meaning calories from "added sugar" is not inherently bad. They only become ‘bad' when excess fat gain occurs. If you see a product with HFCS and a similar product with natural sugar, don't assume the product with natural sugar is any better. Ultimately these sugars are all digested the same, depending on whether it is fructose or glucose obviously. Now, I'm not saying that you should go out and consume all the sugar that you want, but look at this from a health perspective! All carb sources contain different amounts of macronutrients, micronutrients and fibre. For example sweets compared to oatmeal. Oatmeal is packed with fibre, vitamins and minerals, as well as antioxidants and other important nutrients. I do believe that the majority of your diet should be made from minimally processed nutrient dense carbs, looking to reduce your intake of added sugar, but of course, there is room to eat your favourite ‘junk' food in moderation too. The amount obviously varies person to person depending on goals, calorie intake, and physiological aspect, but this is why it is important to view the healthiness of your diet as whole and not a single meal! Now in the UK the average adult consumes about 50 calories a day, and the average child consumes approximately 100 calories a day from sugar sweetened drinks, without any compensation for these extra calories. (14) Now having a soda every now and then is no problem but control your total calorie intake, eating lots of micronutrient rich foods, and activity levels first and foremost, before worrying about sugar.
- Sugar Myths!
- Is Sugar Toxic?
- Is Sugar Addictive?
- Should We Avoid Fructose?
References1. Amanda R. Kirpitch, MA, RD, CDE, LDN and Melinda D. Maryniuk, MEd, RD, CDE, LDN. The 3 R's of Glycemic Index: Recommendations, Research, and the Real World. Clinical Diabetes October 2011 vol. 29 no. 4 155-159. 2. Williams SM1, Venn BJ, Perry T, Brown R, Wallace A, Mann JI, Green TJ. Another approach to estimating the reliability of glycaemic index. Br J Nutr. 2008 Aug;100(2):364-72. 3. Boelsma E1, Brink EJ, Stafleu A, Hendriks HF. Measures of postprandial wellness after single intake of two protein-carbohydrate meals. Appetite. 2010 Jun;54(3):456-64. 4. Holt SH1, Miller JC, Petocz P. An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. Am J Clin Nutr. 1997 Nov;66(5):1264-76. 5. Sloth B1, Krog-Mikkelsen I, Flint A, Tetens I, Björck I, Vinoy S, Elmståhl H, Astrup A, Lang V, Raben A. No difference in body weight decrease between a low-glycemic-index and a high-glycemic-index diet but reduced LDL cholesterol after 10-wk ad libitum intake of the low-glycemic-index diet. Am J Clin Nutr. 2004 Aug;80(2):337-47. 6. Aston LM1, Stokes CS, Jebb SA. No effect of a diet with a reduced glycaemic index on satiety, energy intake and body weight in overweight and obese women. Int J Obes (Lond). 2008 Jan;32(1):160-5. Epub 2007 Oct 9. 7.Sievenpiper JL1, de Souza RJ, Mirrahimi A, Yu ME, Carleton AJ, Beyene J, Chiavaroli L, Di Buono M, Jenkins AL, Leiter LA, Wolever TM, Kendall CW, Jenkins. Effect of fructose on body weight in controlled feeding trials: a systematic review and meta-analysis. Ann Intern Med. 2012 Feb 21;156(4):291-304. 8. Surwit RS, Feinglos MN, McCaskill CC, Clay SL, Babyak MA, Brownlow BS, Plaisted CS, Lin PH. Metabolic and behavioral effects of a high-sucrose diet during weight loss. Am J Clin Nutr. 1997 Apr;65(4):908-15. 9. Susanne HA Holt, Janette C Brand Miller, and Peter Petocz. An insulinindexof foods:the insulin demand generated by 1000-kJ portions of common foods. Am J Clin Nutr 1997;66:1264-76. 10. http://weightology.net/?p=434 11. http://weightology.net/weightologyweekly/?page_id=19 12. Fulgoni V 3rd1. High-fructose corn syrup: everything you wanted to know, but were afraid to ask. Am J Clin Nutr. 2008 Dec;88(6):1715S. 13. Sacks FM1, Carey VJ2, Anderson CA3, Miller ER 3rd4, Copeland T2, Charleston J5, Harshfield BJ2, Laranjo N2, McCarron P6, Swain J7, White K6, Yee K7, Appel LJ5. Effects of high vs low glycemic index of dietary carbohydrate on cardiovascular disease risk factors and insulin sensitivity: the OmniCarb randomized clinical trial. JAMA. 2014 Dec 17;312(23):2531-41. 14. Ng SW, Ni Mhurchu C, Jebb SA, Popkin BM. 2012. Patterns and trends of beverage consumption among children and adults in Great Britain, 1986-2009. Br J Nutr. 108(3), 536-51. 15. Cramer MJ, Dumke CL, Hailes WS, Cuddy JS, Ruby BC: Post-exercise Glycogen Recovery and Exercise Performance is Not Significantly Different Between Fast Food and Sport Supplements. Int J Sport Nutr Exerc Metab 2015.