If you’re a woman struggling with breast cancer, you may have heard that sugar feeds cancer. But what does that really mean? There is tons of confusion about this topic, and it’s something I’m sure many of you have read or come across on the Internet.

In fact, you may have come across some of these headlines yourself…

The New York Times: “Does Sugar Feed Cancer? The Science Is Unclear”

CNN: “Sugar does not cause cancer, but it may fuel its growth”

WebMD: “Sugar and Cancer: It’s Complicated”

These articles all discuss the various studies that have been done on sugar and cancer. Some experts believe that too much sugar can fuel cancer, and others indicate that the results are inconclusive.

I’ve spent a lot of time looking at the science behind this claim for my own breast cancer prevention strategies, as well as for my breast cancer coaching clients. Here’s my take on this…

In order to understand the impact of sugar on cancer, we first need to understand what sugar is and why it’s important. So let’s start there…

Why should we try and understand how sugar affects the body?

In the Western world, sugar is a major part of our diet… so we need to understand how it works in our bodies. This wasn’t always the case – in fact, sugar used to be a treat that we only had on special occasions.

These days, sugary foods and drinks are everywhere – they’re cheap and easily accessible, and of course, they taste good. It’s no wonder that so many of us end up eating too much sugar. Let’s look at some statistics…

What do the statistics say?

The World Health Organization (WHO) states that we should have no more than 50 grams of sugar including natural sugars, per day. The average American has 126 grams of sugar a day… that’s around 2.5 times more sugar than what the WHO recommends!!

Canadians take in around 89 grams of sugar a day, while those in the United Kingdom and Australia hover around 93 grams to 95 grams… that’s almost double what the World Health Organization recommends! In a 2019 reference, all four of these countries were in the top 10 list for sugar consumption.

To put this daily dose recommendation into perspective, a medium-sized apple contains 10g of sugar, while a standard 330 mL size can of Coke contains 35g of sugar. So, as you can see, the grams of sugar can add up quickly across both healthy and processed foods items. Unless we’re conscious of our sugar consumption, it’s easy to see how we can exceed our daily sugar intake without knowing it.

The high sugar intake in the United States, according to Healthy Food America, can mostly be attributed to sweetened beverages, such as sodas, energy drinks, sports drinks, coffee, and more. The majority of Americans consume at least one sugary beverage every day.

What is sugar?

There are 4 common forms of sugar:

1)   Fructose – This is also known as fruit sugar and it’s the type of natural sugar found in fruits. It’s important to know that fruit tends to be nutrient-dense and fiber-rich, and it is not something breast cancer patients need to be afraid of… read on to find out why…

2)   Sucrose – This is also known as table sugar and it’s the sugar that’s added to baked goods to make them sweet.

3)   Glucose – This is the main sugar found in carbohydrate foods such as bread, pasta, rice, beans, and vegetables. It is also the main sugar found in your blood and your body’s main source of energy.

4)   Lactose – Lactose or milk sugar is found in milk and other dairy products.

What happens when we eat sugar?

Sugar is a carbohydrate, and carbohydrates include things like sugar, starches, and fiber. Carbohydrates come in 2 basic forms… simple and complex. The difference between simple and complex carbohydrates is essentially how fast they are absorbed and digested in our bodies.

When you eat carbohydrates (simple or complex… it doesn’t matter), they are digested and broken down into glucose which enters our bloodstream. Simple carbs get digested much more quickly than complex carbs, which contain fiber and nutrients to slow down digestion.

Why do simple carbs get digested quicker than complex carbs?

When a food contains a lot of simple or added sugars, your body doesn’t need to do a lot to break it down, since it’s already quite chemically close to glucose, which is what the body breaks carbohydrates down to. Essentially, your body’s job is already partially done since there’s no fiber to slow the whole process down.

On the other hand, a complex carb contains fiber and other nutrients, causing it to absorb much more slowly. This is why you’ll feel fuller, longer after eating complex carbs like steel-cut oats or quinoa instead of downing a plain, white bagel.

What does the body do with carbohydrates?

Once the carbohydrates are all broken down into glucose in your body, your body does 3 things with it:

1) uses what it needs for immediate energy

2) takes what’s left and stores it in the muscles and liver until they reach capacity

3) takes any glucose that remains and converts it into fat, which is stored in unlimited amounts in the body

When there’s glucose in your blood from eating carbs, this triggers your pancreas to release a hormone called insulin into your blood. Insulin is needed to move the glucose from the blood into the cells so that it can be used as fuel for the cell.

So insulin acts like a key, and all cells have insulin receptors, which are like doors that can only be unlocked by the key, which is insulin. But, when there’s too much insulin and all the receptors have already been unlocked, then the signal is given that the extra sugar should be stored.

The extra first goes to the liver and muscle… and if there’s any more left, the excess glucose gets stored as fat.

The problem is when you take in simple sugars like added sugars… eating a lot at once causes your blood sugar levels to rise really quickly, and your body has to release a lot of insulin to take care of it. This causes your blood sugar to drop dramatically a few hours later, and you end up feeling really hungry again. It’s a vicious cycle that can be hard to break out of!

To avoid this blood sugar roller coaster, I would recommend eating complex carbohydrates like those found in vegetables, beans, and whole grains. These take longer for your body to break down, so they don’t cause such big spikes and dips in your blood sugar levels. And, as an added bonus, these complex carbs also tend to be higher in fiber, which helps keep you feeling full longer.

So, as you can see, glucose is essential for the normal functioning of all of our body’s cells… all cells in our body (not just cancer cells) use glucose as fuel.

What is the relationship between sugar and cancer?

The problem is that some cancer cells have up to ten times the number of insulin receptors versus normal cells. So when insulin levels are high, as they are after you eat a lot of sugar or refined carbs, these cancer cells soak up lots of glucose (blood sugar) and use it to fuel their growth.

This is where the phrase sugar feeds cancer comes from. But, as you can see, a lot depends on insulin.

If you eat the right sugars and keep your insulin balanced, then you don’t have the same issue.  It’s when you eat processed carbs and added sugars which are simple sugars… this is what causes insulin to spike. So, it’s sugar’s relationship to higher insulin levels that may influence cancer cell growth.

It’s important to note that protein, fiber, and fat all affect how quickly carbohydrates get broken down into glucose, digested, and absorbed.

So, how do you know if the food you eat is going to spike your insulin, versus more of a slow, steady increase and drop? This is where the glycemic index comes in.


What does the glycemic index have to do with insulin and blood sugar?

The glycemic index (GI) is a value used to measure how much specific foods increase blood sugar levels. A glycemic index (GI) is assigned to each food, with pure glucose (sugar) rated at 100. The lower a food’s glycemic index, the slower blood sugar levels rise after eating it.

Foods that have a high glycemic index are absorbed quickly. These are processed foods such as baked goods, white bread, breakfast cereals, cakes, cookies, white pasta, and white rice.

Foods with a low GI are absorbed slowly – these are the complex carbs, such as vegetables, beans, some fruits, and whole grains, which contain fiber and nutrients. The glycemic index can help guide you into choosing higher quality (slower releasing carbohydrates).

For example, if you are eating a food with a glycemic index of 70, that means it is releasing glucose into your bloodstream at a rate of 70% compared to pure glucose. A food is considered to have a low GI if it is 55 or less, high GI if 70 or more, and mid-range GI if 56 to 69.

The point is that rather than focusing just on sugar, what we should be focusing on is ways to keep our insulin levels balanced and in check, and the way to do that is simple… eliminate added sugar in the form of processed carbs and stick to complex carbs in the form of vegetables, beans, whole grains (buckwheat, quinoa, steel-cut oats for example), and fiber-rich fruit such as apples and berries.

 Let’s talk more about fruit…


Fruit and breast cancer recovery

As long as you’re eating a whole food, mostly plant-based diet, I feel that the benefits of eating fruit outweigh any risks, especially if you do it in a thoughtful way. Several ways to do this include:

1) Choose fiber-rich fruit that has a lower glycemic index such as cherries, apples, lemons, and strawberries.  

2) Combine a piece of fruit with a fat such as a nut butter so that the protein and fat in the nut butter slow down the breakdown and release of sugars into the bloodstream

3) Incorporate fruit as part of your meal so that its absorption is slowed down by the other components in your meal

Tips to help fight sugar cravings

The sugar habit can be difficult to let go of, especially if you’ve been used to eating sugary foods most of your life. However, it is possible to overcome sugar cravings with a little effort and perseverance. Here are some tips to help you fight sugar cravings that may plague you in your breast cancer journey:

Start where You are At

If you’ve eaten white bread and jam for breakfast your whole life, eating whole grains such as oatmeal may take some getting used to. And that’s okay. Just because you’re trying to be healthier for breast cancer recovery doesn’t mean you have to go from one extreme to the other. Start where you are at and make small changes that you can stick with long term.

Eat fewer carbs for breakfast

If you eat a carb-heavy breakfast, your body will look for more carbs later in the day as it likes the dopamine hit it got from the carbs… and it’ll send signals to you for another dopamine hit, in the form of cravings. So if you have a less carb-heavy breakfast, it won’t activate this reward circuit. For example, switch to a vegetable omelet or steel-cut oats with chia and flaxseeds.

Make Sure You’re Getting Enough Sleep

Lack of sleep can lead to cravings for sugary and high-carb foods. When you’re well-rested, you’re more likely to make healthier decisions. Shoot for 7-8 hours of sleep each night.


Exercise can help alleviate stress and improve your mood, both of which can help reduce sugar cravings. Not to mention, it can help regulate hormones that play a role in sugar cravings such as insulin and cortisol.

Add healthy fats to your meals

Healthy fats help reduce sugar cravings by helping to regulate blood sugar levels and keeping you feeling fuller longer. Avocados, nuts, seeds, and olive oil are all great sources of healthy fats.


With every bite you put in your body, ask yourself, is this going to help me or hurt me? Your body wants to be healthy, so it’s a good idea to give your body what it needs to do its job!  Remember, it’s a journey and every step in the right direction is a step in the right direction.

If you would like more information on nutrition and lifestyle strategies for breast cancer prevention and recovery, CLICK THIS LINK to join my free Facebook group called Breast Cancer Nutrition and Lifestyle Strategies for Prevention and Recovery to help support you in your journey and connect you with like-minded people. 

Disclaimer: Statements on this blog reflect the author’s personal opinions and do not represent the views or policies of the author’s employer, past or present, or any other organization with which the author may be affiliated. They are also not to be viewed as personal medical care or advice, but rather for the purpose of general knowledge. The author does not in any way guarantee or warrant the accuracy, completeness, or usefulness of any message. Should you choose to take action based upon content read on this site, you do so at your own risk and agree to hold the author harmless. Always consult your own physician for medical advice.

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