Having already explored how much protein we should include in our meals, let’s take a closer look at the second macronutrient, carbohydrates, which is the primary source of fuel for our body. In India, 70-80% of total dietary calories are derived from carbohydrates, on average. Most plant foods contain some amount of carbohydrates, and they are abundant in grains, millets, starches, and many vegetables and fruits.
Dietary carbohydrates can be broadly classified into three groups: sugars, starches and fibres.
1. Sugars: Our body uses the simple sugar, glucose as fuel to create the energy required to function. There are three simple sugars, glucose, fructose, and galactose, that our body can use as energy, with glucose being the primary source. Many sugars found in our diet are combinations of these simple sugars. For example, sucrose (table sugar and jaggery) is a combination of glucose and fructose while lactose (found in milk) is a combination of glucose and galactose.
2. Starches: Starches are long chains of simple sugars that account for 70-80% of total carbohydrates in most diets and are abundant in grains, potatoes, and pulses. Our body breaks down starches into simple sugars through digestion. Starches are broadly classified based on how easy it is for our body to break them down into sugars.
- Rapidly digestible starch, found in foods such as white bread, potatoes, and white rice, is easily and quickly broken down into glucose. This leads to a rise in blood sugar which can be utilized for energy or stored as fat.
- Slowly digestible starch, such as those found in whole grains and commonly referred to as “complex carbohydrates”, release glucose at a slow rate, leading to a gradual increase in blood sugar.
- Resistant starch, found in certain whole grains and vegetables, refers to starch that cannot be digested by our body but is used as fuel by the bacteria found in our digestive system. While these starches do not provide energy, they can provide a host of health benefits, similar to dietary fibre.
3. Dietary fibre: Carbohydrates that cannot be digested by our body and used as fuel are broadly referred to as dietary fibre. There are two types of dietary fibre, based on whether they’re soluble in water: soluble fibre and insoluble fibre.
Soluble fibre is found in oatmeal, nuts, seeds, beans, lentils, fruits and vegetables. While our bodies cannot use it as fuel, the bacteria in our digestive tract thrive on soluble fibre, and lead to a number of health benefits. Soluble fibre derives its name from the fact that it absorbs water, bulking up to many times its size.
Insoluble fibre, as the name suggests, does not dissolve in water. These carbohydrates provide bulk to the food we eat, promoting healthy digestion and preventing constipation.Most fibre rich foods contain both soluble and insoluble fibre.
Mostly carbohydrates are considered as an evil food as most of them are consumed in refined form which is known to be associated with obesity, diabetes and heart disease. However, a clearer perspective is lacking in terms of the right type of carbohydrate consumption-both quantity and quality wise, which is why we need to go deeper and learn about the different forms of carbohydrates.
Carbohydrates have been demonized as the root cause of most lifestyle diseases such as obesity, diabetes and heart disease. While the relationship between carbohydrates and lifestyle diseases is true to a large degree, it is important to understand that this applies primarily to those carbohydrates that are quickly digested and converted into sugars. This is normally measured in terms of the Glycaemic Index and Glycaemic Load of foods.
Glycaemic Index and Glycaemic Load
The Glycaemic Index (GI) of a food shows how quickly it releases glucose into the blood and is measured on a scale from 0 to 100, with 100 being the value for pure glucose. High GI foods (GI >70) are quickly broken down into glucose, whereas low GI (<55) foods are broken down very slowly. Avoiding high GI foods is an easy way to reduce the risk of lifestyle diseases by preventing sudden increases in blood sugar.
|Low||0-55||Whole wheat bread
|Medium||56-69||Basmati, Doongara, long-grain and brown rice
|High||70 or more||White bread
Some varieties of white rice (eg. Sona Masuri, Ponni and Surti Kolam)
Cakes and buiscuits
It is important to understand another concept to make informed dietary choices – Glycaemic Load (GL). GL refers to the blood sugar increase that an average serving of a food provides.
Low GL: 1-10
Medium GL: 11-19
High GL: 20 or more
For example, Watermelon has a high GI of 80, but a serving of watermelon provides a very small amount of glucose, given that the fruit is largely water. This gives it a GL of just 5.
While far from perfect, GI and GL provide us with a simple way to make informed decisions on carbohydrates, allowing us to increase carbohydrates with digestive health benefits while reducing those that promote disease.
Carbohydrates and the #perfectplate:
The healthiest, longest living individuals globally consume carbohydrates from a variety of sources such as whole grains, starchy vegetables (such as sweet potatoes) and fruits. Regulatory authorities, such as the FSSAI, also suggest that 50-60% of an individual’s calories should come from carbohydrates.
These recommendations fit well with the #perfectplate, with 50% of the plate consisting of non-starchy vegetables (and fruits), and 25% of the plate consisting of starch or grains. For an individual who requires around 2000 calories a day, this is as simple as adding approximately 40 grams of carbohydrates from grains and starch in each meal. The images below show each show the amount of a common source of carbohydrates that would provide this amount.
It is important to understand your daily calories requirements and decreasing (or increasing) carbohydrate consumption accordingly. This can be easily estimated using calculators such as this. A few other important factors to consider include:
- People with lifestyle issues such as obesity and diabetes can benefit from reducing carbohydrate intake, ideally under the guidance of a dietitian or doctor.
- For vegetarians and vegans for whom daal is their primary source of protein, it may be best to reduce the amount of grains consumed, as daal contains a substantial amount of carbohydrates as well.
- Athletes, especially those engaged in endurance sports, may benefit from increasing carbohydrate consumption due to their increased energy demand.
In our next post, we complete the #perfectplate by filling in the remaining 50% with vegetables and fruits.
1. Bae SH. Pediatr Gastroenterol Hepatol Nutr. 2014 Dec; 17(4): 203-208.
2. Brouns F, et al. Nutr Res Rev. 2005 Jun;18(1):145-171.
3. Eleazu CO. Afr Health Sci. 2016 Jun; 16(2): 468-479.
4. Holesh JE and Bhimji SS. Physiology, Carbohydrates. 2018. StatPearls Publishing: Treasure Island (FL). Available from: https://www.ncbi.nlm.nih.gov/books/NBK459280/
5. Kanter H. Nutr Today 2018 Jan; 53(1): 35-39.
6. National Institute of Nutrition. Diatary Guidelines for Indians – A Manual. 2011. Available from: http://ninindia.org/DietaryGuidelinesforNINwebsite.pdf7. Shobaba S, et al. Int J Food Sci Nutr. 2012 Mar;63(2):178-83.
8. Slavin J. Nutrients. 2013 Apr; 5(4): 1417-1435.
9. World Health Organisation. WHO calls on countries to reduce sugars intake among adults and children. World Health Organisation Media. Available from: https://www.who.int/mediacentre/news/releases/2015/sugar-guideline/en/