About sugars and addiction…


If I started cutting the use of added sugars (from being a sugar-holic to reducing my intake to almost zero) in my initial attempts to follow the Zone Diet (circa 2005-2006), it was not until around 2008 that I started to become almost obsessed about avoiding them. It was before the recent witch-hunt against added sugars (at least before it got more media and social attention) and I remember reading on a news webpage something like “Sugar is more addictive than cocaine”… It obviously caught my attention, so I read on, found the link to the original scientific paper and tried to find out if it was just another big media claim or science was actually behind it… Much has been written since then and with that, much more I have been reading and learning… What follows is a quick journey into what I learnt about sugars, to try to understand why they have become the number one suspects for the obesity epidemic, why I strongly believe that cutting their intake is a necessity for health and wellbeing and possibly giving you some practical tips on how to control / reduce their intake…

I will divide the topic on sugars into several subsections (as different posts, all starting with the “About sugars and…” title line) as I realise that one single post would probably have most of you sleeping halfway through…! I hope that by going through the different sections, not only you will keep alert and interested, but also you will be able to more easily find the part you are most interested in for future reference…

Before I continue, I would like to point out a couple of things:

  1. Most of these posts will be about added sugars, which represent a very small portion of the carbohydrate family. Do not take these posts as a generalisation about carbohydrates (I will talk about different types of carbohydrates in future posts). If you are not sure about what is a sugar and what is a carbohydrate, or what is the difference between fructose and sucrose (among many others), hopefully you will know by the end…
  2. For those of you who want to do what I did, here is the link to the freely available original paper I just mentioned: Intense Sweetness Surpasses Cocaine Reward (Lenoir et al, 2007). For those who cannot be bothered, but are just curious, I will start this post with a summary of what the researchers did, and discovered..

The researchers wanted to compare the addictive effect of sweet taste (saccharine, but also sucrose in one part) and cocaine in laboratory rats. After all the preparation which ensured an appropriate learning phase (the rats knew what they were choosing, as thoroughly described in the paper), they divided around 100 rats into 3 groups (C+/S-; C-/S+; C+/S+). Rats were placed in identical cages, in which two levers were connected to two “feeding” systems. In the C+/S- group, if the rat pressed the C-lever (linked to the cocaine feeder), they would receive a cocaine dose, but nothing would happen if they pressed the S-lever (linked to the saccharine feeder). In the C-/S+ group, if the rat pressed the S-lever, they would receive a saccharine-sweetened beverage in their cage, but nothing would happen if they pressed the C-lever (no reward). The C+/S+ would receive either their cocaine dose or their sweetened beverage, according to their choice. Here is what happened:

What the rats chose
What the rats chose


The empty circles are the C+/S- group. When only the cocaine lever gave the reward, then rats ended up predominantly choosing the C-lever.

The full triangles are the C-/S+ group. When only the saccharine lever gave the reward, then rats ended up predominantly choosing the S-lever.

Now the first interesting finding in the full circles (the C+/S+ group). When the rats could choose between the cocaine and the saccharine reward, they behaved almost in the same way as if the C-lever did not give them any reward: essentially they predominantly favored saccharine over cocaine (!!!).

But then the scientists went further.

They wanted to see how cocaine-addict rats would behave when exposed to saccharine. To test this reaction, they took the rats that had previously shown preference for the C-lever in the C+/S- condition together with other rats which had been self-administering cocaine for up to three weeks. They put them in the same condition as the C+S+ condition (free choice of either cocaine or saccharine) and here is what happened…:


Cocaine to Saccharine Addiction
Cocaine to Saccharine Addiction


As you can see, after an initial period of preference for cocaine, almost all rats switched to the saccharine lever by day 10…!!! Cocaine-addict rats preferred saccharine-water to cocaine if given the exclusive choice…!!! The authors concluded their article presenting some hypothesis about the neurological pathways activated by cocaine and sweetness and how saccharine could surpass cocaine as an addictive substance.

It is important to note here that not only the experiment was on rats, so translation to humans should be done cautiously (actually many studies since then have also identified an addictive behavior of foods – sugars and fats in particular – on the human brain, please see my link page for more info…). The scientists also used saccharine (a sugar substitute, not a sugar itself) as it is much sweeter than sugars. They however reported that similar results were obtained with sucrose. In addition what I am interested in, is actually the addictive property of the sweet taste, not of the particular substance as it is the taste addiction that can go on to play a major role in human health…


If you are shocked as I was after reading about the addictive properties of sweetness (and sugars are sweet…), you will probably understand why I decided to spend much attention into understanding more about this food category. So what is a sugar? And what are carbohydrates? Are they the same? And what about the sugars in fruit? And vegetables? Why is more likely that you would crave a dessert than some broccoli? I have been surprised over the years about the lack of general knowledge about food and nutrition… After all, we make a “conscious” choice  (is it really conscious?) several times a day: what shall I eat? And despite this, very few people know the difference between proteins and carbohydrates, or if vegetables are good or bad sources of proteins, or if they are rich in sugars… If it is normal not to be a food scientist or to analyse each snack at the microscope, I hope that by the end of this post you will not only know a bit more about carbohydrates, but most importantly, you will be able to make that conscious choice a bit more consciously…

Sugars are a subclass of carbohydrates. Consider a carbohydrate (also called saccharide) a construction made of many small pieces. Each piece is only made of Carbon and Water (hence the name carbo-hydrate). If the construction has only one (mono-saccharide) or two (di-saccaride) units, it is referred as a sugar. Other carbohydrates can be made of up to 3000 single units… So, point number one: every sugar is a carbohydrate, but not every carbohydrate is a sugar…

Glucose is a sugar in its simplest form, it is one of the major sources of energy in our body and it is made of only one unit (a mono-saccharide). Like glucose, fructose and galactose are also monosaccharides and if the chemical difference among them is minimal (mainly related to the three-dimensional structure in the case of fructose and the position of one chemical link in the case of galactose), their behaviour in our body is very different. It is also important to know that galactose is barely present alone in nature, while it binds to glucose to form lactose (a di-saccharide I’m sure you have heard of…). On the other hand, fructose is commonly present naturally in fruits and plants (although, do not be fooled by the name, it does not mean that fruit only contains fructose!). Fructose is also (and very importantly when talking about diet and “un-health”) a major component of sodas and processed foods under the name of High Fructose Corn Syrup) or it also can bind to glucose (roughly 50% each) to form sucrose (another di-saccharide, the common table sugar you use for your daily dose in coffee, tea, cakes, etc…). Sucrose is also the sugar form present in fruit (as I just mentioned it is not only fructose at all!). Fructose is sweeter than glucose and its role in human nutrition has dramatically changed with the industrial production of High Fructose Corn Syrup (HFCS), a cheaper sugar than glucose or sucrose. HFCS is still made of a combination of fructose (anything up to 55%) and glucose (the remaining part) but differently than from in sucrose, in HFCS the two mono-saccardies are not chemically linked. Glucose can also be found alone in nature (in honey, partly in fruits and plant-foods) although the highest stake in the food industry nowadays is in desserts and processed foods. As discussed, it can bind to galactose (to form lactose) and to fructose (to form sucrose) or less commonly to another glucose unit to form maltose. Point number two: fructose is sweeter and its industrially manufactured form (HFCS) is cheaper than glucose. For this reason the food industry (sweetened drinks in particular) has almost completely substituted the use of sucrose or glucose with High Fructose Corn Syrup. Point three: glucose, fructose and galactose are the smallest units of carbohydrates and are assimilated differently in our body. Point number four: glucose is a constituent (with fructose) of most of the sugars commonly used in home-cooking (sucrose), while fructose alone is the most common sugar used in most industrially-processed foods (because it is cheaper and sweeter). 

When more than one or two single units of carbohydrates bind together, then oligo- and poly- saccharides are formed. These are still part of the carbohydrate family but while sugars provide essentially immediate energy to plants or animals, longer chains have generally storage (starch in plants and glycogen in animals) or structural roles (think about the hard “backbone” of celery, or just the “skeleton” of plants and flowers). To this latter category belong the well-known fibers. Because of their structure and complexity and the lack of specific enzymes in humans, fibers are not absorbed by our bodies (similarly to the subclass of starches called “resistant starch”). They therefore travel through our digestive system, attracting water to them (hence their role in softening the stools). Because we cannot digest them, fibers and resistant starches are also often recommended to dieters because they make you feel full although eventually your body does not take much energy (calories) from them. Carbohydrates that go through the digestive system without being absorbed are often left for our intestinal bacteria to digest. Because in essence they are food for our intestinal bacteria, those “undigestible” carbohydrates are often referred to as pre-biotics (they support the bacteria). PS: pre-biotics should not be confused with pro-biotics, which are live bacteria that are considered beneficial to our organism and we ingest from food (most commonly with yogurt). Point five: starches and fibres are more complex forms of carbohydrates than sugars. Point six: fibers and resistant starches are not absorbed by humans, while giving a sensation of fullness and keeping the stools soft by attracting water. Point seven: pre-biotics are eventually digested by our intestinal bacteria, which take great benefit. A healthy intestinal bacteria has been linked to a myriad of positive effects for our body, so in essence, eating pre-biotics makes you feel full, gives you little calories, spoils your intestinal bacteria which in turn give back plenty of benefits (and some gases…) .


Classification and nomenclature of common carbohydrates
Classification and nomenclature of common carbohydrates


As this series of posts need to focus on added sugars, I will now get back on track (I thought a brief digression was worth just to at least make sense of some common words often misused or not well known) with a discussion on the different effects of different types of sugars on the body and why these differences are relevant in my post “About sugars and metabolism”. This will lead to the practical post “About dietary sugars: grocery shopping and eating advice”.

Stay tuned and please feel free to comment, add more, critique, ask or just say hi…! 😉