Why Is Sugar Bad For You?

by | Jan 11, 2018 | Nutrition

The Dirt:

Too much sugar causes obesity, which is linked to a variety of health problems. Sugar is often a hidden ingredient in food making it even more difficult to measure how much you eat. Why is sugar bad for you, and how much can you safely eat each day?

Following an indulgent holiday season, the Dirt-to-Dinner team decided to eliminate added sugars from our diet. And more than that, we wanted to understand the risks associated with eating excess sugar. What is sugar doing to us and should we kick the habit all together?
The average American eats between 90 to 110 grams of added sugar a day. This equates to about five cups of sugar a week. This is roughly 50 grams over the recommended daily allowance by the American Heart Association, which advises us to eat no more than 25 grams or 6 teaspoons per day for women and 36 grams or 9 teaspoons per day for men.

What is worse: “high in fat” OR “high in sugar”?

Foods that are “high in fat” have been blamed for many health issues in the United States. When President Dwight Eisenhower had a heart attack in 1955 Americans began to investigate the relationship between prevalent diseases and sugar. His doctors divided into two camps over what was to blame: sugar or fat.
Unfortunately for the American public, foods high in fat became the culprit for his health problems and sugar was deemed safe for consumption. The food industry took note and started creating “healthier” foods that were “low fat.” And in order to compensate for the bland taste and ‘mouth feel’ that occurred without  the presence of fats, sugar was added as a substitute.
Today, 31% of Americans are obese. One American dies every 40 seconds of cardiovascular disease, 9.4% have type 2 diabetes, and 34% of Americans are pre-diabetic. Is this a coincidence or is sugar to blame?
Now, sugar has been deemed the new poison. The New York Times, The Guardian, and The New Yorker have all written about the toxicity of sugar. And documentaries, such as That Sugar Film and Fed Up, highlight sugars adverse effect on our health.
However, until it is possible to perform research that incorporates human trials, it is very difficult to state these claims definitively. Of course, it is much easier to feed sugar to rats and see the results than perform the same experiments on humans. In fact, while the National Institutes of Health has several studies that point to the adverse effects of sugar on our health, it also has published studies that indicate the results of fructose consumption are inconclusive.

Added sugar vs. naturally occurring sugar

Many of our readers have asked about the sugars found in fruit and dairy products. Fruit is packed with fiber, vitamins and minerals! Yes, it does contain naturally occurring sugars, but the fiber present will slow down the glucose and insulin peaks. (For more on glucose vs. fructose read our previous post on sugar.) Chewing fruit adds to your satiety and prevents you from overeating. Fruit juice, on the other hand, is packed with sugar and does not have the same fiber content. Even if it doesn’t contain added sugars, we recommend skipping the fruit juice and eating your fruits!

The sugar found in dairy is called lactose. Lactose does not contain fructose. However, dairy products can have added sugars, which do contain fructose— and that sugar counts as added sugar. Be sure to grab the unsweetened yogurt options, drink milk, and eat 2 servings of fruit a day.

The research says…

Too much sugar hurts your brain. Yes, glucose feeds our brain, but the excess consumption negatively affects on our brain signals. Our brain cells need 2x more energy than our other cells, which is roughly 10% of our diet. Too much fructose reduces a chemical called brain derived neurotrophic factor (BDNF). This helps with repairing and protecting brain cells, forming connections and make new memories. A low level of BDNF causes all sorts of issues such as low concentration, limited memory, and even depression.

Fructose is not metabolized by our bodies so it gets stored in our liver as fat. When the liver can’t hold any more, it will send the fat to the organs in your body and around your belly. A diet high in sugars is strongly associated with metabolic syndrome – which means that everything your body regulates starts to fall apart.  It is the precursor to heart disease, diabetes, and inflammation. The first sign of metabolic syndrome can be something as simple as visceral fat.

Finally, a new study from the University of Texas MD Anderson Cancer Center showed a link between breast cancer and sugar. Mice on a sucrose diet, containing fructose, were approximately 60% more likely to develop mammary tumors.

Why do we have sugar cravings? 

Eating a high sugar diet makes you want to eat even more! Because it doesn’t take as much energy to process sugars as it does protein and fat, so your body processes sugar much faster. So fast, in fact, that your body can’t tell that you are full.  High peaks and lows in both glucose and insulin create a craving for more food 2-3 hours after you ate a high glucose load. The snacking continues – the calories build – and weight gain follows.
Ever had a sugar high? Sugar rushes energy through your body as the insulin enters through your blood stream. This is often followed by a fast decline because there was so much glucose in your blood stream that insulin can’t keep up and your cells don’t get the energy they need. This tells your brain to eat more sugar in order to get more energy. It is a never-ending cycle that most people are on throughout the day: up and down and up and down.

The negative effect of sugar is not an overnight phenomenon – it is a slow progression. It could start with eating too many sweets with not enough exercise. Or your LDL (bad cholesterol) could be too high. Keeping a poor diet for a longer period could then cause you to develop a pre-diabetic condition of insulin resistance. This, combined with a high level of triglycerides, will start to take its toll on your health. Continuing this bad diet over a period of several months or years would then begin to deteriorate your health. (Read our post on inflammation for more insight on the link between unhealthy digestion and cancer.)

What can you do?

The average caloric consumption per capita in the United States is 3,750 calories per a day. That is approximately 1,750 more calories than we need. Additionally, on average, Americans sit 10 hours a day and this doesn’t even include sleep! In order to get healthy, something has to change. The good news is that all the negative effects of sugar can be reversed once you ‘quit the habit’ and start making better choices!

Excess sugar has health consequences, but let’s be honest – there are more factors to blame, as well. No one sits down and eats a plate of plain cane sugar.

If you are not exercising, start. Exercise burns the triglycerides before they turn into visceral fat. Exercise also reduces stress, which makes you happier and helps reduce your cravings. Not to mention, stress and obesity are linked.
If you walk out of the grocery store with a cart filled with overly processed food and no vegetables, start writing and sticking to a shopping list, and stay away from the center aisles. Going to the grocery store is even more fraught with unexpected purchases. 60% of grocery store purchases are unplanned – and most of those are in the center of the grocery store, where all the processed foods are kept. Added sugar is literally everywhere. If you removed all the items from the shelves in the grocery store that have added sugar, you would eliminate 80% of the food in the center aisles.

If you crave sugar sweetened drinks, then start to wean yourself off them. Sugar sweetened drinks are a major culprit because they pack so much sugar into one small product. Meta-analysis have shown that drinking two 16 oz sugar sweetened beverages a day can cause diabetes, metabolic syndrome and cardiovascular disease. They are a companion to a meal, they don’t fill you up, and you can exceed the recommended allowance sugar. We associate sugar drinks with sodas such as Coke, Pepsi, or Dr. Pepper, yet they are found even in ‘healthy’ drinks such as fruit juice, ice teas, expensive cleanses and sports drinks. Energy drinks are particularly fraught with sugar.

From the D2D team: Recipes to satisfy your sweet tooth without added sugar!

The Bottom Line: 

Sugar is now believed to be the root of many long-term diseases for which fat was wrongfully blamed. Be aware of the sugar you eat every day, or you will find it easy to exceed the AHA daily recommendation. Try cutting it out of your diet for a week— we promise you will feel better!


Ahmed, S H, et al. “Sugar addiction: pushing the drug-Sugar analogy to the limit.” Current opinion in clinical nutrition and metabolic care., U.S. National Library of Medicine, July 2013, www.ncbi.nlm.nih.gov/pubmed/23719144.

Avena, Nicole M., et al. “Evidence for sugar addiction: Behavioral and neurochemical effects of intermittent, excessive sugar intake.” Neuroscience and biobehavioral reviews, U.S. National Library of Medicine, 2008, www.ncbi.nlm.nih.gov/pmc/articles/PMC2235907/.

Bray, G A, and B M Popkin. “Dietary sugar and body weight: have we reached a crisis in the epidemic of obesity and diabetes?: health be damned! Pour on the sugar.” Diabetes care., U.S. National Library of Medicine, Apr. 2014, www.ncbi.nlm.nih.gov/pubmed/24652725.

DiSalvo, David. “What Eating Too Much Sugar Does to Your Brain.” Forbes, Forbes Magazine, 10 Aug. 2012, www.forbes.com/sites/daviddisalvo/2012/04/01/what-eating-too-much-sugar-does-to-your-brain/#61c6eaa74a19.

Johnson, Richard J., et al. The sugar fix: the high-Fructose fallout that is making you fat and sick. Pocket Books, 2009.

Taubes, Gary. The case against sugar. Anchor Books, 2016.

That Sugar Film, http://thatsugarfilm.com/

“WHO guideline : sugar consumption recommendation.” World Health Organization, World Health Organization, www.who.int/mediacentre/news/releases/2015/sugar-guideline/en/.

Wilson, Sarah. I quit sugar: the complete 8-Week program. Pan Macmillan, 2012.