By Dr. Mercola

Researchers have found strong associations between excessive sugar consumption and rising rates of obesity and major diseases such as diabetes, cancer, heart disease and Alzheimer's. 

High-sugar meals are a problem largely relegated to the processed food industry. You don't really have this problem when you're cooking from scratch with whole foods. Unfortunately, most people still eat far more processed foods than real foods, and the health consequences of this choice are significant. 

According to a 2014 study,1 10 percent of Americans consume 25 percent or more of their daily calories in the form of added sugars. Most adults (71.4 percent) get at least 10 percent of their daily calories from added sugar. 

People who consumed 21 percent or more of their daily calories in the form of sugar were TWICE as likely to die from heart disease compared to those who got 7 percent or less of their daily calories from added sugar. The risk was nearly TRIPLED among those who consumed 25 percent or more of their calories from sugar. 

That means at least 10 percent of the adult population in the U.S. are in this tripled-risk category. Once you understand metabolic biology, it is absolutely no surprise to see these stats; in fact it is precisely what you would expect.

High-Sugar Diets Promote Heart Disease in Kids Too

More recent research shows that high-sugar diets are also a significant risk factor for cardiovascular disease in CHILDREN — and pose a significant risk even far below current levels of consumption.

As noted in the latest scientific statement on children's sugar consumption from the American Heart Association (AHA), which they finally admitted to, recognized and published last month in the journal Circulation:2

"Strong evidence supports the association of added sugars with increased cardiovascular disease risk in children through increased energy intake, increased adiposity, and dyslipidemia … 

[I]t is reasonable to recommend that children consume ≤25 g[rams] (100 cal[ories] or ≈ 6 teaspoons) of added sugars per day and to avoid added sugars for children <2 years of age." 

Considering the fact that heart disease is the leading killer of Americans,3 cutting sugar consumption is not a matter to be taken lightly. As a parent, you have a significant amount of control over your child's health destiny. 

Of course this recommendation falls far short of what is ideal for children. which should be less than 1 teaspoon of sugar per day.

How Sugar Affects Your Brain

Another recent study sheds new light on sugar addiction by explaining how sugar affects your brain cells. As reported by The Independent:4

"Our brain cells — which have the highest sugar consumption of all organs — control our metabolism and feelings of hunger more than previously believed…"

Researchers at the Technical University of Munich used positron emission tomography (PET) imaging to demonstrate that insulin and leptin direct and regulate sugar intake into your brain cells — both neuronal cells and non-neuronal cells.

When insulin receptors on the surface of astrocytes (non-neuronal cells that maintain homeostasis in your brain) are missing, you end up with impaired hunger regulation, which can result in overeating and feeling hungry all the time.

Dr. Matthias Tschöp, director of the Division of Metabolic Diseases, told The Independent:

"Our results showed for the first time that essential metabolic and behavioral processes are not regulated via neuronal cells alone and that other cell types in the brain, such as astrocytes, play a crucial role."

Additionally, it is well known that sugar will increase dopamine release (the feel good neurotransmitter). The more sugar you consume the more resistant you become to dopamine's effect and the more you need, somewhat similar to insulin resistance.

Ketones Are a Better Brain Fuel 

While your brain is one of the most "sugar-hungry" organs in your body, it is well known that your brain does not require glucose. It actually functions better when you're burning ketones — a byproduct created when your body burns fat as its primary fuel.

In fact, evidence suggests it may be the brain's constant burning of glucose that is primarily to blame for Alzheimer's and other neurodegenerative disorders. 

In people who have diabetes, Alzheimer's or Parkinson's, for example, certain neurons have become insulin resistant or have lost the ability to efficiently utilize glucose. As a result, neurons begin to die off. When ketones are present, these neurons may be spared; they may even begin to thrive again.

Severe Obesity Can Cut a Decade Off Your Lifespan

High-sugar diets and regular soda consumption are a primary cause of obesity,5which has long been recognized as a risk factor for many diseases that can cut your life short. 

Coronary heart disease, stroke, respiratory disease and cancer are but a few diseases associated with obesity that raise your risk of premature death. A recent study that looked at data from nearly 4 million adults from 32 countries, found that:6

  • Overweight individuals with a body mass index (BMI) of 25 to 29.9 lost approximately one year of life expectancy
  • Moderate obesity (BMI of 30 to 34.9) cut life expectancy by three years
  • Severe obesity (BMI of 35 to 39.9) can cut as much as 10 years off your lifespan

Interestingly, excess weight appears to take a far greater toll on the health of men, as their risk of premature death was three times higher than that of obese women.

Among men, the risk of dying before age 70 was 19 percent for those of normal weight and 29.5 percent for the moderately obese. Among women, the risk of death before age 70 was 11 percent for those of normal weight, and only 14.6 percent among the moderately obese. 

This equates to an absolute increase in risk of 10.5 percent for men and a 3.6 percent increase for women.

I suspect this is related to the higher iron levels that men typically have. Women have lower levels due to blood loss during their periods. Iron excess combined with insulin resistance is a powerful synergy for disease. You can review my earlier article on ferritin that goes into more detail.

Sugar Recommendations Are Changing

For the longest time, there was no real cutoff recommendation for sugar, aside from recommendations to eat sugar "in moderation" — something that is virtually impossible to do if you're eating processed foods. This is finally changing. The AHA now recommends limiting daily added sugar intake to: 7,8,9,10,11,12,13

  • 9 teaspoons (38 grams) for men
  • 6 teaspoons (25 grams) for women
  • 6 teaspoons (25 grams) for toddlers and teens between the ages of 2 and 18 
  • Zero added sugars for kids under the age of 2 

The National Institute of Health (NIH) has also issued sugar recommendations, suggesting kids between the ages of 4 and 8 limit their added sugar to a maximum of 3 teaspoons a day (12 grams), and children age 9 and older stay below 8 teaspoons. 

The reality is that virtually everyone would benefit from the under age 2 recommendation.

Kids Eat Three Times More Added Sugar Than Recommended for Health 

According to the AHA, kids eat on average 19 teaspoons of added sugar a day — about three times more than recommended, and the evidence clearly indicates that this dietary trend goes hand in hand with our current epidemics of obesity and chronic disease.

A single can of soda or fruit punch can contain about 40 grams of sugar, making sweetened drinks particularly risky for young children. Breakfast cereals, cereal bars, bagels and pastries also tend to contain high amounts of added sugars, making the standard American breakfast a recipe for disease and premature death.

Dr. Miriam Vos, an associate professor of pediatrics at Emory University and Children's Healthcare of Atlanta and the lead author of the AHA statement on sugar, told Reuters:14

"Sugar can influence people's health in a number of ways. For example, it's tied to weight gain, higher cholesterol levels, worse blood sugar control and fatty liver disease. All of those are known — the cholesterol levels, weight gain, insulin resistance and fatty liver — to increase cardiovascular risk in adulthood." 

Twenty-five grams of sugar per day is my recommended limit as well, with the added caveat that if you're among the 80 percent who have insulin or leptin resistance (overweight, diabetic, high blood pressure or taking a statin drug), you'd be wise to restrict your total fructose consumption to as little as 15 grams per day until you've normalized your insulin and leptin levels. 

I have personally chosen to consume an ultra-low carb diet with no added sugars and about 15 to 35 grams of net carbs a day (total carbs minus fiber) in the winter when sunlight is low. During the summer I double this intake by adding fruit that I grow on my property in Florida. My favorite are 50 to 70 acerola cherries that supply about 80 mg of vitamin C each.

Sugar Association Responds 

Not surprisingly, the Sugar Association is none too pleased with the AHA's sugar recommendation, which they call "baffling." In an August 24 press release, the Sugar Association responds saying:15

"In a year where both the 2015 Dietary Guidelines for Americans (ages 2 years and up) and the Food and Drug Administration's (FDA) final labeling rule (ages 4 years and up) issued a 10 percent target for added sugars in an effort to provide Americans a tool to help build a healthy diet, the AHA is releasing their own vastly different recommendations. 

The AHA is recommending 6 teaspoons of added sugars for an active 16-[to] 18-year-old boy — this is just 3 percent of his calories … The conversation around added sugars has gotten out of control and the beliefs of individuals are trumping what the scientific evidence actually shows…"

They go on to note that the AHA's "hyper-focus on added sugars contradicts the advice of the American Academy of Pediatrics (AAP), which historically has been the expert voice on children's diets." The notion that the Sugar Association would want the AAP's recommendations to rule the roost is no surprise considering the years the sugar and junk food industries have spent lobbying and donating millions to influence the AAP! 

Not only has the Sugar Association been a "corporate partner" of the AAP,16 but the AAP also accepted $3 million from Coca-Cola Company for the creation of a children's health website.17 In other words, the sugar industry already has the AAP in their proverbial pocket. Now they have to fight for their right to sell high-sugar foods to youngsters all over again, which means cooking up more biased studies to support their untenable position. 

To learn more about the dirty underbelly of the sugar industry, see my previous articles, "Sugar Industry Secrets Exposed," "Sugar Industry Has Subverted Public Health Policy for Decades," or "How the Sugar Industry Hoodwinked You about the Dangers of Sugar, Using Big Tobacco Tactics." I have also interviewed Gary Taube about his new book on sugar that goes into great detail on these topics. That interview will run this fall. 

Obesity Now Linked to More Than a Dozen Cancers

High-sugar diets feed not only obesity but also cancer. According to The Cancer Society, excess weight contributes to about 20 percent of all cancer cases, and recent research from the U.S. Centers for Disease Control and Prevention (CDC) suggests cancer may soon overtake heart disease as the No. 1 killer of Americans. As reported by CBS:18

"As of 2014, cancer has passed heart disease and is the leading cause of death in 22 states … In the year 2000, it was the leading cause in only two states."

Researchers also warn that obesity will soon overtake smoking as a principal cause of cancer. All of this makes perfect sense once you understand the nutritional science behind it. Sugar increases insulin and IGF-1 which are very powerful activators of mTOR, which suppresses autophagy and your body's ability to terminate cancer cells.

In summary, cancer cells need glucose to thrive, and carbohydrates turn into glucose in your body. In order to starve the cancer cells, you have to eliminate its primary food source, i.e., the sugars, which include all non-vegetable carbohydrates. Otto Warburg received a Nobel Prize back in 1934 for his research identifying cancer's primary fuel was from anaerobic fermentation of glucose. More recent research19 has also concluded that sugar appears to actually INITIATE cancer growth.

Based on a review of over 1,000 studies, an analysis published in The New England Journal of Medicine (NEJM) has now identified another eight cancers associated with obesity, in addition to the several previously identified.20,21,22 Overweight women also increase their risk for breast, endometrial, colon and kidney cancer the longer they remain overweight, and for some cancers, the more overweight you are, the greater your risk.23,24 The cancers currently linked to excess weight are:








Gall bladder



Meningioma (brain cancer)


Multiple myeloma (blood cancer)



How Sugar Feeds Cancer

One of the key mechanisms by which sugar promotes cancer and other chronic disease is through mitochondrial dysfunction. When your body burns sugar for its primary fuel, far larger levels of reactive oxygen species (ROS) are created, which generate secondary free radicals that cause mitochondrial and nuclear DNA damage, along with cell membrane and protein impairment.

Late-night snacking, especially with carbohydrates, can magnify these risks. There is quite compelling evidence showing that when you supply fuel to the mitochondria at a time when they don't require large amounts, like when you are sleeping, the system generates excessive and unnecessary ATP, which in turn liberate ROS, setting into motion the same cascade of mitochondrial and DNA damage as just described.

There's also evidence to indicate that cancer cells uniformly have damaged mitochondria, so eating shortly before going to bed is likely a very bad idea, considering your cells need the least amount of fuel when you're sleeping. Personally I strive for six hours of fasting before bedtime.

Proper Diet Can Significantly Reduce Your Risk of Cancer 

In the lecture above, orthopedic surgeon Dr. Gary Fettke reviews the evidence showing that eating a diet high in healthy fats and low in net carbohydrates (total carbs minus fiber, i.e. non-fiber carbs) may significantly reduce your risk of cancer. Fettke is one of several people now promoting the metabolic model of cancer.

Earlier this year I also interviewed Travis Christofferson, author of a phenomenal book called "Tripping Over the Truth: The Return of the Metabolic Theory of Cancer Illuminates a New and Hopeful Path to a Cure," on this topic. In a nutshell, the nuclear genetic defects typically thought to be responsible for cancer actually occur further downstream. Mitochondrial damage happens FIRST, which then triggers nuclear genetic mutations that may lead to cancer.

The good news is you can optimize your mitochondrial function by addressing your diet and exercise. As Fettke notes, one of the primary considerations is glucose metabolism within your mitochondria. Sugar "feeds" cancer while fats "starve" it. 

Healthy cells can use either glucose or ketone bodies from fat as an energy source, but cancer is metabolically restricted to using glucose only. Cancer cells for the most part lack metabolic flexibility and simply cannot metabolize ketones, and this is why nutritional ketosis appears to be so effective against cancer. 

High-Fat, Low-Sugar Diet Cuts Inflammation

Inflammation is also a major driver or mitochondrial damage that can lead to cancer (and many other chronic diseases), and our modern processed food diet is HIGHLY inflammatory. Key culprits include polyunsaturated fats (PUFAs), trans fats and added sugar in all its forms, especially processed fructose (such as high-fructose corn syrup), as well as refined grains. Artificial ingredients can also promote inflammation.

By reducing the amount of net carbs you eat and replacing them with healthy fats, you accomplish four things that will result in lowered inflammation and reduced stimulation of cancer growth. You will:

  • Lower your serum glucose level
  • Reduce your mTOR level
  • Reduce your insulin level
  • Lower insulin growth factor-1 (IGF-1, a potent hormone that acts on your pituitary gland to induce metabolic and endocrine effects, including cell growth and replication. Elevated IGF-1 levels are associated with breast and other cancers) 

Indeed, one of the basic reasons why a diet high in healthy fats and low in net carbs (nutritional ketosis) works so well for general health and disease prevention is because it drives your inflammation down to almost nothing. And when inflammation disappears, your body is far less predisposed to disease and/or can heal from whatever ails you. 

As noted by Fettke in the lecture above, research into the metabolic foundation of cancer presents us with a whole new set of cancer prevention and treatment options, including the following: 

  • Limit or eliminate sugar and net carbohydrates (non-fiber carbs) to avoid feeding cancer cells
  • Limit or eliminate PUFA oils and trans fats to prevent the formation of harmful free radicals and damaging small, dense LDL particles
  • Limit protein (I recommend using a formula of one-half gram of protein per pound of lean body mass) to avoid stimulating mTOR pathway
  • Increase antioxidant intake (via whole foods and/or supplements) to counteract free radical damage
  • Increase healthy fat intake to feed healthy cells while starving cancer cells. Healthy fats include avocados, coconut oil, MCT oil (a particularly great source of ketones), raw grass-fed butter and pastured egg yolks, just to name a few 

High-Sugar Diets Also Fuel Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD), which affects up to 25 percent of Americans,25 is defined as an excessive accumulation of fats in your liver in the absence of significant alcohol consumption. NAFLD is also the most common type of chronic liver disease in children.26 The overconsumption of net carbs, especially fructose in soda and juices, is strongly associated with NAFLD which, if left untreated, can raise your risk of hepatocellular carcinoma (liver cancer).

The reason for this is because, contrary to other sugars, nearly all of the fructose you consume gets shuttled to your liver, and — if you consume high amounts of it — your liver is taxed and damaged in the same manner that it's damaged by alcohol and other toxins. 

As noted in one 2015 study: "Ingested carbohydrates are… more likely to directly contribute to NAFLD than dietary fat intake."27Research from Tufts University shows that drinking even a single sugary drink each day will raise your risk of liver damage and NAFLD.28

Tips for Reducing Your Added Sugar Intake

One of the most important ways to dramatically cut down on your sugar and fructose consumption is to simply eat real food, as most of the added sugar you end up with comes from processed foods. Other ways to cut down on the sugar in your diet includes:

  • Cutting down, with the aim of eliminating sugar you personally add to your food and drink or consume in the form of processed foods and sweetened beverages
  • Using Stevia or Lo-Han instead of sugar and/or artificial sweeteners. You can learn more about the best and worst of sugar substitutes in my previous article, "Sugar Substitutes — What's Safe and What's Not
  • Using fresh fruit in lieu of canned fruit or sugar for meals or recipes calling for a bit of sweetness
  • Using spices instead of sugar to add flavor to your meal

Originally Posted: