The Sweet Truth

Sugar has been part of our lives, our plates and our hospital bills for a while now. These lockdown days, when we are making more food choices, are probably a good time to look closer at some sugary facts.

‘Sugar’ and ‘sweet’ have become closely associated in our vocabularies, but all sugars aren’t sweet. In fact all sugars are not created equal either. Dr. M Madhu Bashini, MD (General Medicine), and well-known diabetologist explains, “from what we know now, different types of simple sugars are each metabolised in a certain way, irrespective of their source. So whether the glucose is from jaggery or white sugar or from corn syrup, it is treated by the body as a simple sugar. The differences vis-a-vis sources arise because of the quantity consumed, and because of the other nutrients or fibre that may be present in the food, or the other chemicals present because of processing.” Here is a handy table of sugary facts:

Sugar Type In Our Body Glycemic Index Taste
Glucose Primary source of energy, signals the release of insulin 100 Not sweet
Fructose Metabolised in liver, low impact on blood glucose levels and insulin 19 Very sweet
Sucrose Leads to elevation of blood glucose 65 Sweet
Lactose Raises blood glucose levels after breakdown by lactase 41 Mildly sweet

Knowing how sugar (ie glucose) works in the body is crucial to deciding what kinds of sweet somethings to eat or avoid. So here is an insight into sugar metabolism by Dr. Anupama Paranandi (Internal Medicine): “Two of the key chemicals in glucose metabolism are insulin and glucagon. Insulin removes glucose from the blood circulation by allowing the cells of the body to take in glucose for normal function. Glucagon allows for breakdown of fuel sources in the body (glycogen in the liver and fats throughout the body) to allow for enough glucose to be in the system during a fasting state. A fine balance between the two in a healthy person allows tight control of blood glucose levels.”

“It’s worth mentioning that there is insulin - independent glucose metabolism in muscle cells. This comes into play with any activity or exercise that is glucose demanding. So, one can ‘preserve’ endogenous insulin (i.e., the insulin made by the body)with exercise. Essentially, glucose metabolism is a complicated set of regulatory processes, with innumerable enzymes and hormones, either directly (e.g., insulin) or indirectly (e.g., cortisol) regulating it, but any type of food you consume eventually gets converted to glucose and then processed for use by the body, except for fructose, the sugars in fruit. Fructose can be metabolised in the liver, which converts it to glycogen (a fuel source in the liver) and fat. This is not a problem if you eat natural fruit, as a significant amount of the fructose from fruit either gets used up by the bacteria in your gut or is converted in your gut to glucose. Therefore, only a fraction of the fructose from whole fruits is transported to the liver for conversion to glycogen and fat.”

In fact, it’s very difficult, if not impossible, to take in too much fructose from eating whole fruits. This is because:

- Fruits are naturally high in fibre. Fibre induces a feeling of fullness and satiety, causing you to stop eating long before the fructose in the fruit reaches anywhere near excessive levels. (This is not the case with fruit-juice, mind you. For instance, 3 medium-sized oranges would make only 1 cup of orange-juice. You could certainly drink up a cup of orange juice in one go, but it’s unlikely that you would eat 3 full oranges at a time. Further, eating 3 oranges would probably make you feel very full, but the juice wouldn’t do this at all, making you go searching for something else to eat as well! If the juice had added sugar, then all those simple sugars would immediately hit your blood stream at once causing a dramatic spike in insulin and promoting weight gain.

- Fructose is the sweetest of the simple sugars. So the amount of fructose that makes a fruit taste sweet, is LESS than the amount of sucrose it would take to make an artificial food taste as sweet.

But we all know this. We all know eating fruits is a better idea than eating candy, cake, juices and beverages with added sugar, and other manmade desserts which have added sugar. Then why do we have these things? The answer may seem obvious - because eating sweet things ‘feels’ good - but this answer is not entirely satisfactory, is it? It’s not satisfactory because there are so many caveats to this answer. Not everyone has sugar cravings. Even if they do, not everyone always gives in to sugar cravings. Even if they do give in, there’s so much variability to it - some are satisfied with one small piece of candy, while some may have a large tub of chocolate ice-cream and still want more. This would mean the issue is not so much with the sugar without, but the decision-making within. Has decision-making got something to do with sugar within? Turns out it does indeed! To understand how, we need to turn to a milestone study on ego depletion - a using up of mental resources to make decisions - conducted by Dr.Roy F Baumeister et al (1998) that helped him understand and explain the construct of decision fatigue,
the tenet that each decision we make depletes our reserve of will-power and makes subsequent decision-making more difficult and error-prone.

It was an experiment following this one, conducted by then-graduate student Matthew Gailliot, that brought to light conclusive evidence that people who had just eaten were able to perform better on lab tasks requiring the exercise of will-power. The interesting and relevant part for us here is that what they ate did not alter their level of will-power - a luscious, thick milkshake full of added sugar produced comparable results to a “tasteless concoction of low-dairy glop”. To establish cause and effect, researchers at Baumeister’s lab tried a series of experiments involving lemonade mixed either with sugar or with a diet sweetener. The sugary lemonade provided a burst of glucose, the effects of which could be observed right away in the lab; the sugarless variety tasted quite similar without providing the same burst of glucose. Again and again, glucose in the blood restored willpower, but the artificial sweetener had no effect. The glucose would mitigate the ego-depletion and sometimes completely reverse it. The restored willpower improved people’s self-control as well as the quality of their decisions: they resisted irrational bias when making choices, and when asked to make financial decisions, they were more likely to choose the better long-term strategy instead of going for a quick payoff.


As with any new finding, the idea that glucose in the blood translates to will-power in behaviour had believers as well as nay-sayers. As it happens, it was one of the initial skeptics, Dr.Todd Heatherton, who later conducted his own research, and reported that “administering glucose completely reversed the brain changes wrought by egodepletion” - a finding, he said, that thoroughly surprised him. 'Heatherton’s results not only provided further evidence that glucose is a vital part of willpower; they helped solve the puzzle over how glucose could work without
global changes in the brain’s total energy use. Apparently, ego depletion causes activity to rise in some parts of the brain and to decline in others. Your brain does not stop working when glucose is low. It stops doing some things and starts doing others. It responds more strongly to immediate rewards and pays less attention to long-term prospects.’

Coming back to food choices, and eating to sugar-filled snacks, the sweet taste of the snack is an immediate reward. We are able to resist it in two cases - one when we have enough glucose in our blood already and two, when we have not been making a whole host of decisions in the last few hours, ie, our ego is not depleted. Let’s look at the second option first - in today's world, we are surrounded by options, and we continually make decisions. Exercise or sleep? Which card? Meet someone now or later? Google Meet or WebEx? Whose WhatsApp msg should I respond to first? Which news site do I believe? And on and on…

So there’s hardly a time when we are not suffering from decision-fatigue, especially because the more decisions you’ve already made, the more ‘depleted’ you are. So the way to avoid sugary (and harmful) snacks is to already have enough glucose in your blood. Is that a catch-22 situation? That to avoid eating sugar, you must already have sufficient sugar in your blood? Not really, because when you eat complex carbohydrates, they are digested and assimilated gradually, providing your body with sustained fuel over a long duration.

“Therefore,” concludes Dr.Paranandi, “the most effective way to minimise sugar cravings, maintain good health and fitness, and be kind to your body, is to consume foods in their least processed forms. Such foods would be organically grown fruits and vegetables and whole grains.” It’s an added bonus that this is not only the way to maintain good health, but, also to have more will-power and be better at as crucial a life-skill as decision-making.

If you would like to read some decision-making tips and techniques, click here 

Last modified onWednesday, 18 November 2020 17:31
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