Dispelling Myths

Too Much Can Make Us Sick

1. I’ve never heard about metabolic syndrome, MetS.  Is that a real disease?

Nutritional scientists and physicians have been concerned about, and studying MetS for many years. It is unfortunate that information about MetS still isn't widely known.  That’s why SugarScience was created – to share what we know with the public. 

MetS is a syndrome, not a specific disease.  It allows physicians to distinguish people who are at high risk for a wide range of chronic diseases, such as diabetes, heart disease and liver disease before they actually get those diseases. For nutrition scientists, it is a major focus for understanding the causes of, and mechanisms involved, in chronic diseases. MetS is a very hot topic of research. A search for information in PubMed, the US National Library of Medicine's database on biomedical information, shows that 7,000 articles have been published about Metabolic Syndrome and how it is related to diet or nutrition in the last 10 years alone.

2. I get that we should be concerned about chronic diseases – the things that lead to premature death. But having too much added sugar still increases your risk of being overweight and obese, right?

Of course, obesity is a complex problem and no single component of the diet explains the entire picture. Other dietary components, along with genetics and physical activity, also influence weight gain and obesity. Being overweight is itself a risk factor for many forms of chronic disease, as well as being an indicator of metabolic syndrome (MetS). Yet the vast majority of scientific evidence supports the conclusion that consuming too much added sugar is one factor that promotes weight gain, which can lead to obesity. This conclusion is based on numerous studies and repeated careful reviews of the evidence. Decreasing sugared beverage consumption alone would likely have a significant impact on America’s obesity epidemic.

Some scientists question whether the dramatic increase in added sugar consumption in America since the early 1980s is a significant factor in today’s obesity epidemic. After all, the obesity epidemic also coincided with an overall increase in the total calories that average Americans consume and a more sedentary lifestyle. These are important points to consider. Some scientists believe that a phenomenon called “leptin resistance” helps explain what’s going on. Consuming too much added sugar, over a long period of time, often leads to changes in hormonal regulation and specifically to changes in how the brain interprets the signal from the hormone leptin, which helps regulate appetite. Two symptoms of leptin resistance are increased calorie consumption and reduced physical activity levels. Sugar-induced leptin resistance could help explain why Americans have been eating more and exercising less.

3. How solid is the evidence showing that heavy sugar consumption impacts chronic diseases?

The amount of research and evidence on this, varies across different categories of chronic disease. Scientists on our SugarScience team generally agree that there is now compelling evidence that prolonged, heavy consumption of added sugars increases the risk of developing Type 2 diabetes, heart disease, and fatty liver disease. In addition, there are active research programs looking into the potential for added sugar consumption to impact the development of other chronic diseases, such as Alzheimer’s disease (or senile dementia) and some cancers. However, we believe that more research is needed in these areas before drawing conclusions.

Bear in mind that one can always find studies that don’t support these conclusions. Due to differences and limitations in research methods, it is typical for there to be some disagreement among studies conducted on the same topic. In some areas, it may be too early to draw conclusions, because scientists just haven’t had enough time to build up a large body of evidence. What is important to consider is not what any one study says, but the overall body of evidence. This is typically processed into “systematic reviews” that take the varying quality of research methods into account when evaluating a whole body of evidence. When subjected to this kind of intensive scrutiny, the evidence on sugar and chronic disease is strong enough that the nation’s foremost authorities, as well as the World Health Association, are now advising people to limit their intake of added sugars in order to prevent chronic disease.

It is also important to bear in mind that some of the published research may be biased, due to industry conflicts of interest. For instance, internal documents from companies that produce table sugar, high-fructose corn syrup (HFCS) and other sweeteners were publicly released this year following a court settlement. These documents show that companies sometimes support scientific studies to show that sugar consumption has no adverse health effects. While not all science supported by industry is biased, recent systematic reviews show that industry-funded studies on sugar are less likely to report evidence of health harms than those funded by more neutral entities, such as the U.S. National Institutes of Health. Scientists are required to report funding sources and potential industry conflicts of interest when they publish their studies in peer-reviewed science journals. At SugarScience, we take this, along with many other factors, into account during our reviews of the evidence.

Finally, in considering the evidence, its important to focus on the most recent studies and carefully performed, systematic reviews. This is important, especially in a dynamic area of science such as this, in which new studies are being published every week. For example, as recently as 1997 and 2003, an expert panel convened by the United Nations’ Food and Agriculture Organization and World Health Organization (WHO) concluded that there was not adequate evidence of health hazards to set limits of sugar intake. However, just this year, a new WHO panel concluded that the evidence is now sound enough to sets a dietary limit on sugar consumption.

4. Aren’t most of the studies on added sugar and chronic disease observational? Isn’t this kind of evidence weak?

Observational studies are those that study people in their day-to-day lives instead of putting people in labs or studying already-sick people in randomized clinical trials. The main advantage of these studies is that they capture people in their real-world lives, suggesting that study findings are often directly relevant to people like you. Another is that some of the best studies track groups that are representative of the general population over very long periods of time – sometimes most of the lifespan. The downside is that these studies can be messy: there are many factors that influence the development of chronic disease. We have to use highly sophisticated statistical modeling to isolate the unique role that the overconsumption of added sugars plays in the onset and promotion of chronic diseases.

So, in addition to observational studies, we need laboratory experiments on people and animals, and sometimes randomized trials to confirm what we’re seeing. Most of these are short-term, and rely on markers of disease (e.g., changes in hormonal levels), rather than the disease itself (e.g., heart disease).

At SugarScience, we primarily report to you research findings that are “robust,” in the sense that there are well-designed observational, clinical and laboratory studies that all point to similar conclusions. To increase our confidence in the accuracy of what we report, we also confine ourselves to results that have been “replicated,” or observed in multiple studies by different investigators. Taken together, findings from all of these sources provide us with a fuller understanding of whether and how heavily added sugar consumption impacts disease outcomes over time.

Sometimes, it’s just not possible to conduct all of the studies that, as scientists, we’d like to see performed. For instance, often the “perfect study” from a research standpoint would simply be unethical and even illegal – for example, a randomized controlled trial in which some people were given an unhealthy diet, high in added sugar, over a prolonged period of time, to observe whether or not they acquired a chronic disease. However, randomized studies over shorter periods of time have shown that heavy doses of added sugars in healthy volunteers produce pronounced changes in metabolic health, which are precursors to chronic disease.

5. Is it fair to pick on one component of the American diet, such as added sugar?

The development of chronic disease is, of course, a complex process involving multiple risk factors. Many of the risk factors in chronic disease, such as genetic predisposition, cannot be controlled. However, the environment can be controlled. Diet is one factor that is within the control of individuals and societies. Added sugar is an easily identified source of extra calories in the diet and is something we have the ability to change. Cutting down on sugary drinks, for instance, is fairly simple to do.

Recent trends further explain why focusing on added sugar is important. Since the early 1980s, American’s have experienced rising epidemics of obesity and related chronic disease. It is unlikely that the source of these epidemics lies in our underlying genetic code, which changes only gradually. So, we must look to changes in the environment to explain what’s going on. One of the biggest changes in our diet has been a dramatic increase in added sugar consumption; meanwhile the proportion of fats and proteins in the American diet has remained relatively stable. Today, the average American consumes almost three times more added sugar than is conducive to good health. This warrants focusing special attention on this specific component of our diet.

6. Fruit is loaded with sugar. Is fruit bad for you?
Fruit does have sugar, but it also has something much more important: fiber. The amount of sugar in most fruits is proportional to the amount of fiber. The fiber does three things that mitigate the problems posed by the sugar. First, it reduces the rate of absorption of sugar in the intestine, so your liver doesn’t get overwhelmed. Second, because it delays absorption, more sugar is metabolized by  bacteria in the intestine for energy, so it isn’t absorbed into the body. And third, the fiber speeds the transit of the food through the intestine, so you get the satiety (stop eating) signal sooner. Studies show that the metabolism of apples versus apple juice is very different. Furthermore, fruit reduces risk for diabetes, while fruit juice increases diabetes risk.

World Health Organization

The World Health Organization (WHO) is the directing and coordinating authority for health within the United Nations system. It is responsible for providing leadership on global health matters, shaping the health research agenda, setting norms and standards, articulating evidence-based policy options, providing technical support to countries and monitoring and assessing health trends. Website:

SugarScience Glossary

Conflicts of interest

Researchers have conflicts of interest when their work is significantly dependent on a funding source that holds a vested interest in the outcome of their research.

SugarScience Glossary

Added sugar

Any sugar added in preparation of foods, either at the table, in the kitchen or in the processing plant. This may include sucrose, high fructose corn syrup and others.

SugarScience Glossary

Sugary drinks

Means the same as sugar-sweetened beverages or liquid sugars.

SugarScience Glossary

Heart disease

A broad term for a group of chronic diseases of the heart, these diseases include problems with blood supply to heart muscle, problems with heart valves and the electrical system of the heart. Another term you will see used to mean the same thing is cardiovascular disease.

SugarScience Glossary

Table sugar

Sucrose, also called granulated sugar, is two simple sugars stuck together in a single molecule. Sucrose is made of one fructose and one glucose molecule. On this website, one level teaspoon of table sugar weighs 4.2 grams and has 16.8 calories.

SugarScience Glossary

Metabolic syndrome

Also called Syndrome X is a group of body abnormalities that go along with increased risk of cardiovascular disease, type 2 diabetes and stroke. The definition of this syndrome varies a little worldwide.

SugarScience Glossary

Metabolic syndrome

Also called Syndrome X is a group of body abnormalities that go along with increased risk of cardiovascular disease, type 2 diabetes and stroke. The definition of this syndrome varies a little worldwide.

SugarScience Glossary

Liver disease

A broad term meaning any bodily process in which the liver is injured or does not work as it is supposed to. In this website we focus on liver diseases in which the diet hurts the liver

SugarScience Glossary

Fruit juice

This is a drink that is made entirely (100%) from the liquid which comes from squeezing or grinding up the part of the fruit we would normally eat. Sugar is not added to this drink. The drink will have the sugars that come from the food itself. The juice will likely have less fiber than the fruit. Fiber serves to decrease the speed and amount of sugars absorbed from sugary foods.

SugarScience Glossary

Diabetes mellitus

Usually shortened to just diabetes. Sometimes called sugar diabetes. Look at Type 1 Diabetes and Type 2 Diabetes for more information

SugarScience Glossary

Chronic diseases

Diseases which last months or years, do not go away on their own, and are usually managed and not cured. For the first time in history diseases that are not caused by infection (non-communicable diseases) are causing more injury and death worldwide than are those caused by infection. In the US this has been true for decades but the rest of the world is catching up as our diet and lifestyle are becoming more common globally.

SugarScience Glossary


Sugars are chemicals made of carbon, hydrogen, and oxygen found which taste sweet and are found in food. They are an important part of what we eat and drink and of our bodies. On this site, sugar is used to mean simple sugars (monosaccharides) like fructose or glucose, and disaccharides like table sugar (sucrose). Sucrose is two simple sugars stuck together for example (see Table sugar). Sugars are a type of carbohydrate. Carbohydrates are energy sources for our bodies Sugars enter the blood stream very quickly after being eaten.

SugarScience Glossary


A hormone produced mostly in fat cells in response to eating and to how much energy is stored in the body. It effects the brain and tells us we have eaten enough and to stop eating.

SugarScience Glossary


A group of chronic diseases of the brain that cause, memory loss, behavior changes, and abnormal thinking and reasoning.

SugarScience Glossary


A sugar that we eat. Also called fruit sugar. Most fructose comes in sucrose (table sugar, cane sugar, beet sugar), or from high-fructose corn syrup.

SugarScience Glossary


The largest internal organ. It weighs about three to four pounds and is located under the lower edge of the ribs on the right side. It helps us digest our food and remove toxins from our blood. "Hepat" in a word means liver, so an "hepato-toxin" is a liver poison or something that can cause damage to the liver

SugarScience Glossary


A chemical created by the body and released into the blood stream. Upon reaching another part of the body or organ, a hormone effects the function of that bodily part or organ.

SugarScience Glossary

SugarScience Facts

To make foods "low fat," many food companies replaced the fat with added sugar.

SugarScience Facts

Today, 31% of American adults and 13% of kids suffer from non-alcoholic fatty liver disease (NAFLD).

SugarScience Facts

Too much fructose in added sugar can damage your liver just like too much alcohol.

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