What I learned when I gave up sugar for six weeks

Foods with added sugar are everywhere – even in some surprising places. So how easy is it to go without sugar and what difference can it make to your health?

While I typically eat a healthy diet with plenty of home-cooking, I also have a sweet tooth and tend to consume a chocolate treat or two every day.

That's not very surprising – overconsumption of sugar is extremely common in our modern diets. It's bad for our teeth, harmful to our health and there is even some evidence to suggest eating too much sugar might lead to long-term cognitive deficits.

As my role involves reporting on health and wellbeing, I've increasingly started to worry about eating so many treats, which alongside refined sugar, often contain numerous additives. In fact, one of my regular treats contains more than half my daily recommended amount of sugar.

Dietary guidelines in the US recommend consuming fewer than 12 teaspoons of added sugar from food and beverages (around 50g) while in the UK, the NHS recommends people eat less than seven teaspoons (30g) of sugars per day. In reality US adults eat more than 16-17 teaspoons (65-70g) a day, according to the US National Health and Nutrition Examination Survey. To put that in context, 4g is about one level teaspoon of sugar.

Giving up all that sugar isn't easy either. But I decided to see if it was indeed possible to break out of my daily sugar habit.

I set myself the challenge of not eating any foods containing added refined sugar for six weeks. I also avoided honey and fruit juice but I continued to eat natural sugars found in whole fruit, as well as complex carbohydrates – which when eaten, our body breaks down into the sugar glucose which provides our body and brain with its main source of energy.

From the outset, I noticed some surprising changes to my energy levels and how I felt. The post-lunch slump went away but I did often find myself listlessly looking in my fridge trying in vain to find something interesting (sweet) to munch on, feeling as though I was missing out.

Sugar is everywhere

First, it's worth reflecting on just how much sugar is added to our food. I found it surprisingly hard to avoid. Browsing my local supermarket shelves, I noticed it in food I didn't expect, including a deli sourdough sandwich, which contained 5.7g of sugar and a bolognese ready meal (9g). Many breakfast cereals include added sugars and a slice of commonly bought supermarket bread had about 1.2g of sugar per slice.

Sugar is also abundant in many ultra-processed foods – which have known adverse health outcomes and tend to contain fewer nutrients than whole foods like fruits, vegetables and whole grains.

There are many different forms of sugar in our foods. Glucose is perhaps the most common, but you can also find fructose in fruits and many syrups, lactose in milk and sucrose, which is commonly known as table sugar and is one of the main forms of added "free sugar" in our diets. Free sugars area also found in juices, syrups and honey as they are not bound up in the cells of our food. These refined free sugars contribute most to adverse health effects.

"We come out of the womb liking sweet tastes, it's part of mother's milk in those early days where you're supposed to be gaining a lot of weight," says Ashley Gearhardt, a professor of psychology at the University of Michigan. The problem, she says, is that "we've gotten so good at delivering sweetness really cheaply".

What sugar does to us

Research shows that when we consume high-sugar foods it rapidly increases our blood sugar levels. While that's a normal process after eating, if they happen too often we can become resistant to insulin, and the risk of developing type 2 diabetes increases. High-sugar diets are also linked to cavities, inflammation, obesity, Alzheimer's disease and cancer.

"Diet related diseases like diabetes are now killing people beyond the scope of alcohol and opiates and [unhealthy food] is competing with tobacco for being the most deadly substance in the world," says Gearhardt.

For instance, sugar has been found to increase fat in the liver. In one randomised controlled trial, those who consumed high-sugar drinks for several weeks showed about double the amount of fat in their liver, even if they consumed the same calories overall.

Fructose – such as that found in corn syrup – is toxic to mitochondria, the cellular machinery that keep our bodies running, explains Robert Lustig, co-author of the trial and a leading expert on the harms of sugar. "What it does is it basically knocks out mitochondria, and reduces energy expenditure, so you have to build new ones." This can make you feel lousy, fatigued, tired, irritable and increase brain fog, he tells me.

I certainly noticed my energy stayed more level during the day as the weeks of avoiding sugar went on.

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Emerging research also suggests that diets high in sugary foods are associated with greater mental distress, including symptoms of anxiety and depression.

While all this sounds alarming, as part of a healthy diet sugar is fine in moderation, but it's clear that minimising it would benefit the health of millions who eat too much.

Addictive properties

In the first few days of going without sugar, I craved it intensely, especially when offered tasty treats at social events.

There's a biological reason this is the case. When we eat sugar it can alter our brain chemistry in a way that mimics what you see when individuals are addicted to opioids, explains Lina Begdache, a registered dietitian and associate professor of health and wellness at Binghamton University in the US.

Eating sugary food also activates the brain's reward system. Research suggests that people who experience stronger cravings for sugary foods may also show a greater increase in the "feel-good" hormone dopamine when they consume them – meaning we feel pleasure and reward when we eat sweet foods.

Numerous experts therefore consider sugar to have addictive properties – though this remains an ongoing area of debate.  

Other naturally sweet foods like fruit can then become less interesting for our dopamine system, adds Gearhardt.  

In fact, the stronger the desire for sugar, the greater the reward we feel – which reinforces the cycle and could rewire our brain to crave more of it. For instance, the brains of participants who consumed a high-sugar, high-fat pudding daily for eight weeks became significantly more responsive to sugary foods.

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This dopamine feedback loop helps explain why cutting back can feel so difficult. "You're a hostage to your biochemistry" Lustig says. "That's the definition of addiction. And 20% of the [US] population is sugar addicted."

To resist temptation, I found satisfying alternatives such as a banana and blueberry shake with a spoon of cocoa powder. Grapes had a similar effect. Even apples tasted sweeter too so even if I didn't feel like one, I munched on one daily anyway, which helped keep cravings at bay.

Evidence also shows that individuals are hungrier after rapid blood-sugar drops, a pattern common after eating high-sugar foods. One study found that participants who consumed a milkshake high in concentrated sugar and refined starches (a high glycaemic index shake), were hungrier four hours later and had more activation in the brain's reward centre, compared to those who consumed a low glycaemic index shake.

What is happening when we give it up?

Within days of giving up sugar, however, the body begins to expect less of it, Dalia Perelman a dietician from Stanford School of Medicine in California. told me. My taste buds will have begun adapting, becoming more sensitive to sweet tastes. Giving up industrially sweetened foods allows the taste system to "recalibrate to the intensity of natural sweetness", Gearhardt says

About three weeks into my experiment, something curious started to happen. I was no longer regularly craving sweet treats. If I did get a bit peckish mid-afternoon, I found myself snacking on healthier alternatives, including olives, nuts and fruit.

One reason my cravings went down is simply due to reduced exposure to sugary food, which in turn altered my palate and reset my metabolism, says Begdache.

"You'll see that your threshold for tasting the sugar has gone so much lower that you won't need as much," adds Perelman. She now only eats low-sugar home-made cakes as she finds anything shop bought is like "eating a cube of sugar".

Begdache explains that my levels of triglyceride – a common type of fat in the body which increases when we consume excess calories – will have reduced too. My insulin sensitivity will have improved, as I will have been experiencing fewer insulin spikes that occur in response to sugary foods. "It's like resetting to default," she says.

That said, at family events – and even on my own birthday party – it did feel challenging not to have even a tiny bite of cake. Cravings never felt far away due to how much sugary food was in my immediate environment.

Still, as my sugar intake fell, the sense of reward, often linked to dopamine release, likely diminished.

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Reduced sugar diets have other health benefits too. In one small experiment, a team asked a group of 41 children to give up added sugars for just 10 days. By the end, their blood pressure and body fat fell and they had lower insulin resistance as well as improved behaviour.

Other research, looking at ultra-processed food – which tends to be high in sugar, found that when people ate minimally processed food, they had fewer cravings and more energy.

Having a clearer picture of what sugar does to my body, it made it easier to change my habits – sweet treats just became less appealing. I was also able to limit my exposure to sweet treats at home and ensuring I had plenty of healthy snacks to hand. I also swapped juices for fizzy water with a drop of lemon juice, finding it quenched my thirst.

Reintroducing sugar

By the end of the six weeks, I can truly say I wasn't particularly tempted to reintroduce sugar to my diet. It's likely the "addictive loop" in my brain had been silenced, Begdache told me.

I no longer crave sugary snacks daily and foods with added sugar – even low-sugar breakfast cereals – simply taste too sweet for me now. This change should make it easier to avoid returning to a daily sugary treat, Perelman says.

So now my six-week experiment is over, will I be returning to my sugary treats? In short, no. But I plan to make a few changes.

Rather than avoid added sugar completely, I'll restrict my abstinence to weekdays, allowing myself the luxury of a treat at the weekend. I'm also reframing how I think about sugary food in the first place.

When I did finally reintroduce some sugar in the form of a triple chocolate chip cookie (28g of sugar per cookie), I didn't feel like eating it at all. I forced myself for the purposes of this article to see how my body would respond.

It tasted far too sweet and I could taste more sugar than chocolate. I felt an energy slump soon afterwards too and had a mid-afternoon nap, only possible because I was on an annual leave.

That treat I used to eat regularly was no longer a treat. I stopped after a few bites.

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