All good things come in moderation
I’ve never been one to turn down something sweet. A bar of chocolate to reward myself for a successful grocery shop, some dessert after dinner—since I only indulged a few times a week, I thought it was pretty harmless.
But after noticing how sluggish, irritable, and foggy I felt after sugar-heavy days, I started wondering: could my sugar intake be affecting my mental health?
With that question in mind, I decided to cut out added sugar for an entire month. No packets of jelly beans, no sweetened boba teas, and no honey in my morning oats. The goal wasn’t just to see how my body felt, but to observe whether eliminating sugar had any impact on my mood, energy levels, and mental clarity.
The result? Let’s just say it wasn’t what I expected.
Why I Decided to Cut Out Sugar
I don’t eat added sugar every day. Instead, I tend to indulge in a (very) sweet treat twice a week or so. I usually justify it by saying that I “deserve” a treat—to reward myself for a work victory, to celebrate a special occasion, or to comfort myself after a hard day.
There’s nothing wrong with treating yourself. But I eventually noticed that my sugar binge led to some uncomfortable symptoms, particularly brain fog, poor sleep, and mood swings.
“Excess sugar intake, especially from refined sources, can cause rapid spikes and crashes in blood sugar levels, which can lead to irritability, fatigue, and difficulty concentrating,” says dietician Jessica M. Kelly, MS, RDN, LDN, the founder and owner of Nutrition That Heals. “Over time, frequent blood sugar fluctuations can contribute to increased anxiety.”
“Over time, a high-sugar diet may increase the risk of depression by causing inflammation and disrupting brain chemicals like serotonin and dopamine,” adds Marjorie Nolan Cohn, MS, RD, LDN, CEDS-S, the clinical director of Berry Street. “These ups and downs make it harder to manage emotions, making mood swings more frequent.”
A 2017 study, which looked at data collected from 23,245 people, found that higher sugar intake is associated with depression, particularly in men. Participants with the highest level of sugar consumption were 23% more likely to have a diagnosed mental illness than those with the lowest level of sugar consumption.1
Over time, a high-sugar diet may increase the risk of depression by causing inflammation and disrupting brain chemicals like serotonin and dopamine.
— MARJORIE NOLAN COHN, MS, RD, LDN, CEDS-S
Other research, like this 2024 study, also suggests a link between depression and sugar consumption—but the authors point out this connection might be because mental distress can lead to emotional eating and make it harder to control cravings.2
For the purpose of my experiment, I needed to set some ground rules about the sugars I would and wouldn’t cut out.
According to Kelly and Nolan Cohn, not all sugars affect mental health in the same way. “Natural sugars found in, for example, fruit and dairy, accompany fiber, vitamins, and antioxidants that are health-promoting and slow glucose absorption,” Kelly explains. “Refined sugars, like those in sodas and candy, can cause rapid blood sugar spikes and crashes which can lead to mood swings and brain fog.”
Excited to see the results, I began my experiment!
Week 1: The “Oh Wow, Does That Really Contain Sugar?” Phase
During my first week, I didn’t experience changes in my mood, but rather in my behavior and mindset.
This experiment required me to pick up a new habit: reading nutritional labels and ingredient lists. Although giving up sugar was easy for the first few days, this habit was pretty hard.
I was surprised to learn that sugar is in a lot of things. Most of my favorite savory treats contained sugar. Even my usual “healthy” post-gym treat—a protein bar—was off-limits.
Surprisingly, I didn’t really have any sugar withdrawals, which can be common among people who typically consume a lot of sugar.
“Cutting out sugar can trigger strong cravings since it affects the brain’s reward system, this can lead to withdrawal-like urges, and for some, it can feel very intense,” says Nolan Cohn. Sugar withdrawal symptoms often include headaches, fatigue, and mood swings.
On day four, I had my first major challenge—I realized I could no longer grab some milk chocolate on the way out of the grocery store. Talking myself out of this was harder than I’d like to admit.
The biggest challenge for week one? Choosing what to eat in a restaurant. Most menus don’t specify which dishes contain sugar, and there’s a surprising amount of sugar in savory dishes, like tomato-based curries and wraps filled with sugary salad dressings.
By the end of week one, I felt like giving up. Although I didn’t have any major cravings, constantly checking food labels was annoying, and there were no notable benefits—at least, not yet.
Week 2: A Shift in Mood and Energy
Around the 10-day mark, things started changing for the better.
Even if I don’t eat a lot of sugar in my day-to-day diet and my home-cooked meals, I tend to treat myself—a lot. Food is a go-to source of comfort for me, often to my detriment. My mindset is often along the lines of, “Oh, who cares? It’s just a treat. It’s a special occasion!”
Because I wanted to stick to the experiment, I had to pause my “treat yo’self” mindset. As I was more mindful of sugar, I planned my snacks better, avoided getting takeout, and practiced more self-control while shopping for groceries.
More importantly, I had to actually engage with my feelings instead of eating them away.
On my therapist’s recommendation, I paid attention to the uncomfortable feelings that’d usually lead me to eat, and I journaled about them instead.
I also noticed some changes in my mood—finally! Because I wasn’t eating a lot of sugar and then crashing twice a week, my energy levels felt a bit more stable. This meant that my mood also felt more stable.
Week 3: Mental Clarity and Emotional Balance
By week three, I was genuinely surprised by how good I felt.
Not only was my energy and mood a little calmer, I was really chuffed with myself for managing to avoid sugar for such a long time.
Source: https://www.verywellmind.com/does-sugar-affect-mental-health-11683665