Sugar and Cancer: What the Research Really Says in 2025
My client told me that she felt so torn during her cancer treatment because she felt sick ALL the time - she couldn’t eat her normal foods, but she also knew she needed to eat to stay strong.
She said “The only thing that sounded good was cinnamon rolls - I had to decide if it was safe to eat them or better to go without eating at all”.
Ooof - this broke my heart to hear…because never, in any world, is it better to NOT eat during cancer than it would be to eat the food you can tolerate. Digging a little deeper into her fears, I wasn’t surprised to hear the fear was rooted in the common misconception that “sugar feeds cancer”.
I get it - half of the internet is arguing this to be the case, but the reality is that it isn’t that simple. You have every right to be nervous about eating after a cancer diagnosis.
We absolutely know there is a connection between diet and cancer and you want to make sure you’re not causing the cancer to grow. I’d dare to say nearly every client I’ve worked with has had these exact same fears. You’re not alone.
Let’s break down what the science actually says about sugar and cancer - and what that means for your daily food choices.
We’re getting into ALL of it today:
What’s fact versus myth
How do your blood sugar levels impact cancer risk
Will you ever be able to eat the cinnamon roll without feeling guilty again?
Let’s go 👇
Does Sugar Feed Cancer?
The notion that "sugar feeds cancer" has gained popularity, but it's an oversimplification of complex biological processes. This idea stems from the observation that cancer cells consume more glucose than normal cells—a phenomenon known as the Warburg effect. However, it's crucial to understand that glucose is the primary energy source for all cells, not just cancerous ones. Your brain, muscles, and immune system all rely on glucose to function effectively.
Eliminating sugar entirely from your diet doesn't selectively starve cancer cells; instead, it can deprive your healthy cells of essential energy - which is less than ideal if you’re going through cancer treatments.
You can’t pick and choose where your nutrition goes after you eat. You can’t tell sugar to only go to non-cancerous cells. So yes, cancer cells will use sugar, but it’s not an option to deplete the non-cancerous cells. The cost of depleting your healthy cells would look like poor tolerance to treatment (think poor lab results, hospitalizations, treatment breaks, dosage reductions, reduced quality of life) and longer, more difficult recoveries.
No thanks.
The better way to go about this is to understand what your body needs for support, nutritionally, right now and how you’ll be able to deliver that. The second part of this is understanding what the research actually says, and how do you apply it to your life.
Spoiler…the research doesn’t say to cut out all sugar.
What Does the Research Actually Say?
Recent research indicates that there's no direct link between total sugar or added sugar intake and cancer mortality. (Huang, 2023)
However, excessive consumption of sugar-sweetened beverages (SSBs) has been associated with an increased risk of certain cancers. One study reported that high SSB intake was linked to a 12% higher overall cancer risk and a 7% increase in cancer mortality. Specifically, SSB consumption has been associated with increased risks of breast, colorectal, and prostate cancers (Huang, 2023) .
It's also important to consider the indirect effects of high sugar intake. Diets rich in added sugars can lead to obesity, which is a known risk factor for at least 13 types of cancer. Excessive sugar consumption can also contribute to chronic inflammation and insulin resistance, creating a body environment that may promote cancer development.
Think of it this way, a diet high in added sugars and low in fiber, coupled with sedentary habits, chronic stress, and ultra-processed foods, can create a metabolic environment that increases inflammation, insulin resistance, and overall cancer risk.
But on the flip side, a diet that includes fiber-rich plant foods, regular movement, stress management, and—yes, even including some dessert—can support your whole body, including your recovery.
To summarize: while sugar itself isn't a carcinogen, and there's no evidence that cutting it out completely will prevent or treat cancer, moderating your intake of added sugars is advisable.
Focusing on a balanced diet that includes whole foods and limits (👈 key word) processed, high-sugar items can support overall health and potentially reduce cancer risk.
Different Types of Sugar: Natural vs. Added
Now let’s address an elephant in the room: not all sugar is created equal—and that distinction matters, especially when you're trying to make informed choices during or after cancer treatment.
Natural sugars are the kind found naturally in whole foods like fruits, vegetables, and dairy. These sugars come packaged with fiber, antioxidants, vitamins, minerals, and water—nutrients that work together to support your body’s health, digestion, immune function, and even your microbiome.
Added sugars, on the other hand, are those that are added to foods during processing or preparation. You’ll find them in things like soda or other SSB, sweetened cereals, baked goods, and flavored yogurts. Unlike whole foods, these often come with few beneficial nutrients and can add up quickly in your daily intake—especially in the standard Western diet.
Let’s talk about fruit specifically, because it’s often unfairly lumped in with cookies and soda. Yes, fruit contains sugar—but it also contains fiber, polyphenols, and anti-inflammatory compounds that actually protect your cells. In fact, higher fruit intake has been associated with a reduced risk of several types of cancer, including breast and colorectal cancers. And no, it doesn’t “feed cancer.”
If you’ve ever hesitated to eat a banana or thought twice about berries in your smoothie, please hear this: fruit is not the enemy. It’s one of the most powerful foods you can include in your diet to support your body before, during, and after treatment.
If you’re wondering which fruits are especially beneficial, I’ve got you covered—check out my post on the Best Fruits for Cancer Prevention to learn more about what to prioritize (and how to enjoy them, even if treatment has changed your taste buds or digestion).
How Sugar Affects Insulin and Cancer Risk.
Let’s dig a little deeper into why sugar matters in the context of cancer—and more importantly, how it affects your blood sugar and insulin levels.
When you eat, your body breaks down carbohydrates into glucose (sugar), which enters the bloodstream. In response, your pancreas releases insulin—a hormone that helps shuttle glucose into your cells to be used for energy or stored for later.
This process is normal and necessary.
But here’s where things get tricky: frequent spikes in blood sugar—especially from highly processed foods or meals that lack fiber, protein, or healthy fats—can lead to chronically elevated insulin levels over time. And that matters because insulin doesn’t just regulate blood sugar. It’s also a growth-promoting hormone.
Chronically high insulin and insulin resistance have been linked to increased risk of several cancers, including breast, colorectal, and endometrial cancer (Szablewski, 2024). This doesn’t mean every blood sugar spike is dangerous—but it does highlight why balanced meals are so important, especially for survivors.
What does “balanced” mean? Think of meals that include:
fiber-rich carbs
lean protein
healthy fats
and some color (like fruits or veggies)
These combinations help slow digestion and blunt blood sugar spikes—keeping your energy more stable and reducing stress on your insulin system.
The good news? You don’t need to fear carbs or cut out sugar entirely to protect your health. You just need to be thoughtful about how you're eating, not just what you’re eating.
Should You Cut Out Sugar Completely?
Short answer? No. For most people, especially those recovering from or living with cancer, cutting out sugar completely isn’t necessary—and for many, it can actually do more harm than good.
Yes, we want to be mindful of added sugars, especially the ultra-processed kind that shows up in packaged snacks, sweetened drinks, and desserts. But approaching sugar with an “all or nothing” mindset can quickly become unsustainable, isolating, and frankly, stressful. (Remember that constant feeling of fear about eating we talked about earlier?)
Let’s be real: food isn’t just fuel—it’s also emotional, cultural, and social. From birthday cake with your kids to baking with your mom, or just sharing dessert on date night, these moments matter. And you shouldn’t feel like you’re doing something wrong just because joy is involved.
In fact, I see it all the time—when survivors try to follow rigid, sugar-free “clean eating” plans, it often leads to guilt, shame, or fear around food. That kind of stress doesn’t support your recovery—it chips away at your quality of life.
And guess what? There's no strong evidence that completely eliminating sugar improves cancer outcomes. What does make a difference is building realistic, sustainable habits that support your energy, digestion, and emotional well-being. That includes flexibility, pleasure, and yes, sometimes a brownie.
So instead of asking, “Should I cut this out forever?”—a better question might be: “How can I include this in a way that still supports my health goals, my life, and my peace of mind?”
How to Eat Sweets Without Fear
If you’ve made it this far, you know the goal isn’t to ban sugar from your life—it’s to build a relationship with food that feels empowering, not restrictive. So how do you enjoy sweets without spiraling into fear, guilt, or a blood sugar crash?
Let’s talk mindset first. I often encourage clients to adopt an 80/20 approach: aim to make nourishing, supportive choices about 80% of the time, and leave space for flexibility, celebration, and real life the other 20%. This isn’t about perfection—it’s about consistency, sustainability, and joy.
You can also reframe the way you think about food decisions. Instead of focusing on what to cut out, try practicing “addition over restriction.” Can you add something to that sweet moment—like fiber, protein, or mindfulness—that helps support your body while still allowing for enjoyment?
Here are a few simple ways to make desserts or sweet snacks more blood sugar–friendly:
Pair sweets with protein or fiber: Think a small cookie with a handful of almonds, or fruit with Greek yogurt. These additions help slow digestion and curb blood sugar spikes.
Portion with intention: You don’t need to skip dessert—just enjoy a smaller serving that satisfies you without going overboard.
Eat slowly and without guilt: Rushing through food or feeling ashamed afterward can make it harder to feel satisfied or stay connected to your body’s cues. Try sitting down, putting your phone away, and really tasting that bite.
And if you want real ideas that show you how to practice addition over restriction with sweets, I’ve got a mini menu just for you: check out the Dessert Mini Collection for 10 recipes that are blood sugar–aware, nourishing, and most importantly—delicious.
Signs Sugar Might Be Affecting You Negatively
Let’s be clear: sugar isn’t evil, and you don’t need to fear it. But just like with any part of your diet, it’s helpful to tune in to how your body responds—especially during or after cancer treatment, when energy levels, digestion, and hormone balance may already feel a little unpredictable.
Here are some signs that sugar might be impacting you in a way that’s worth paying attention to:
Energy crashes: Do you feel a burst of energy after a sweet snack, only to hit a wall an hour later? Frequent blood sugar spikes and drops can leave you feeling foggy, fatigued, or irritable.
Cravings that feel out of control: If you find yourself in an all-or-nothing cycle—either avoiding sugar completely or feeling like you can't stop once you start—it may be time to explore how your meals and mindset are playing a role.
Digestive issues: For some people, especially during treatment or with gut sensitivity, too much added sugar can contribute to bloating, irregularity, or microbiome imbalances.
These aren’t signs that you’ve done something wrong—they’re just signals. And with the right support, they can be addressed in a way that still leaves room for flexibility and joy.
If you’re noticing patterns like these and not sure what’s normal or how to respond, that might be a good time to seek personalized guidance. Every survivor’s needs are different, and what works for your sister, oncologist, or the internet may not be what’s best for you.
When to Talk to a Dietitian About Sugar and Cancer
If you’ve ever felt overwhelmed trying to figure out what’s “safe” to eat—or you’ve Googled something late at night and ended up more confused than before—you’re not alone. Nutrition after a cancer diagnosis can feel like a minefield of conflicting advice, fear-based messaging, and unrealistic expectations.
Here are a few signs it might be time to get some personalized support:
You’re feeling anxious, restrictive, or unsure about sugar or other foods
You’ve been trying to manage blood sugar swings, unintentional weight changes, or energy crashes
You want to feel more confident and peaceful about your food choices—not just in theory, but in daily life
As a dietitian who works specifically with cancer survivors, I can help you sort through the noise and build a plan that works for your body, lifestyle, and goals—without guilt, extremes, or unrealistic rules.
If you're ready to take the next step, you can book a free Discovery Call to learn more about my signature program — a high-touch, whole-person coaching experience for survivors who want evidence-based guidance and lasting support.
You don’t have to figure this out alone. I’m here when you’re ready.
FAQs About Sugar and Cancer
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No. You don’t need to eliminate sugar completely to stay healthy or reduce your risk of recurrence. What matters more is your overall eating pattern—focusing on fiber-rich plant foods, balanced meals, and lifestyle factors like movement, stress, and sleep.
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There’s no strong evidence that sugar directly causes cancer recurrence. However, excess intake of added sugars—especially when combined with sedentary habits or poor diet quality—may contribute to insulin resistance and inflammation, which can raise long-term risk. Moderation and balance are key.
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Yes, absolutely. Fruit contains natural sugars, but it’s also packed with fiber, antioxidants, and anti-inflammatory compounds that can support your body during treatment. If you're struggling with taste changes or digestive symptoms, a dietitian can help tailor options that work for you.
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Most artificial sweeteners are considered safe in moderation, but the research is mixed and evolving. Some newer sweeteners like stevia and monk fruit may be better tolerated by those aiming to reduce blood sugar spikes. If you're using a lot of sweeteners daily or have concerns, it's worth discussing with a professional.
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Yes—when sugar is part of a balanced, nutrient-rich diet, there are absolutely ways to include it safely and intentionally. Naturally occurring sugars from whole foods like fruit, dairy, or even small amounts of honey or maple syrup can absolutely fit into a cancer-supportive eating pattern. The key is to focus on how sugar is used—in mindful portions, paired with fiber or protein, and as part of an overall pattern that supports energy, digestion, and wellbeing.
Real Client Stories: Ditching the Fear of Sugar
Let me tell you about my client - when we met, she had just started chemotherapy and one of her big concerns was her unrelenting sweet tooth. She would get “night munchies” and could sit down with a sleeve of cookies intending to eat just a few, and before she knew it, she’d have eaten half (or more) of the package.
No surprise, she told me she felt so guilty over this behavior. She knew this wasn’t helping her, but she also didn’t know how to stop it. And how could she forgive herself for possibly feeding her cancer? The fear & guilt were overwhelming her.
First off - we addressed the cancer sugar misconceptions so she could start releasing guilt & stop fearing food. Second, we took a deep dive into her eating routine. As soon as she started telling me about her meal patterns, it was clear to see why she was getting the munchies & binging late into the night on “feel good” carbs.
She was chronically under fueling her body from the time she woke up every day. Even worse - since she was getting chemotherapy - her body was needing even MORE fuel + consistency. We immediately addressed the imbalance and within a week, she was feeling more control over her cravings - in fact, some days she wasn’t having them at all. And the days she still felt like something sweet? She had more control over her portions (thanks to better balance & blood sugar control) which meant she could eat 1-2 small cookies and feel satisfied.
Goodbye guilt, fear & nightly sugar binge!
Want a Peaceful Relationship with Food After Cancer?
Here’s what I want you to remember: you don’t have to fear food to protect your health.
Yes, nutrition matters. But so do joy, connection, and flexibility. The science supports this too—an eating pattern that prioritizes whole foods, fiber, and balance (without extremes or restriction) is one of the most powerful ways to support your body and your quality of life after cancer.
And you don’t have to figure it all out on your own.
Whether you're navigating survivorship, planning meals that support long-term wellness, or just tired of the stress that comes with every bite—I can help you build a peaceful, evidence-based relationship with food.
👉 Book a free discovery call to learn about personalized 1:1 support
You deserve to feel nourished, empowered, and at peace with your plate. And I’d be honored to support you on that journey.
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