In small amounts and with active people fructose in natural forms (like fruit) is fine because our bodies will immediately use it up as a quick energy source. But in excess it is a hazard because this high intake of sugar repeatedly raises our insulin to the point where are receptors are "blown out". Many people end up with obesity, hypertension, insulin resistance, and type 2 diabetes. On a side note, this is also why many health gurus support eating sugar only in the form of glucose from whole foods (like sweet potatoes and white rice) right after a hard workout. This is because glucose goes straight to the blood stream and will replenish glycogen-- the stores of energy in your muscles. Eating glucose will rebuild your muscles back up right away. On the other hand, we must not get too caught up in one strain of thought and neglect ourselves from wholesome sources of fructose such as fruit. But avoiding processed sugar is crucial.
Before 10,000 years ago humans had not consumed processed sugar. It became domesticated in New Guinea and slowly spread to Asia and by 600 AD to Persia and forward to wherever the Arabs conquered. Eventually the European crusaders fell upon it when they went to save the Holy Land, but the production of sugar was only productive in temperate climates so it became a commodity for the European nobility. Since sugar was so rare in Europe to some it was known as a spice. Eventually trade with the Middle East became too challenging so Europeans looked to other methods during the "Age of Exploration". Columbus planted the first sugarcane in the New World and from there slave plantations and refineries were developed all leading to our obesity problem today.
Before the Agricultural Revolution 10,000 years ago, humans were hunter-gatherers. They didn't have readily available access to carbs and they weren't located in one place to farm and harvest carbs. Because of this our bodies learned to rely mostly on fats and proteins from wild animal sources and scant sources of carbohydrates from any plants that could be foraged in the forest. It definitely wasn't easy and most of the time I am sure some tribes wondered if they were going to survive. This constant deprivation of carbohydrates made our bodies starve for any sugar source. So whenever hunter-gatherers came across a blueberry bush they gorged themselves on it knowing it may be awhile until they find their next one. It made our ancestors wildly efficient processor of fructose: "even small amounts were stored as fat, a huge survival advantage in months where winter lay upon the land and food was scarce". Our brains slowly became hardwired to having this need for sugar. The problem today is that we have the opposite of a shortage of food in America. We have an overabundance-- most in the form of processed sugar and while our brains scream "YES"! our bodies are too sluggish and overweight to keep up with the excitement.
In the 1960s British nutrition expert John Yudkin conducted a series of experiments showing that animals and humans with higher amounts of sugar in the blood had higher rates of fat and insulin, "risk factors for heart disease and diabetes". Unfortunately, Yudkin's message got pushed out of the way as other scientists blamed the obesity epidemic on cholesterol caused by too much saturated fat in the diet. Because of this declaration, fat makes up a smaller portion of our diet today, but obesity rates are still soaring. This is because we have replaced those fat calories with processed carbohydrates. In addition, the fats that most Americans do consume today our refined and high in omega-6 fats which cause major inflammation (think vegetable oils: corn, soybean, canola, sunflower-- any seed or vegetable oils).
As I said before, many of us know that sugar is bad for us but we justify it with cravings. Why do we have these cravings? Because "the injection of sugar into the bloodstream stimulates the same pleasure centers of the brain that respond to heroin and cocaine...it is literally an addictive drug".
Nowadays our world is flooded with fructose and we over-consume it even if we evolved "to get by on very, very little of it". It is a sad irony: that the very product that saved our ancestors is now killing us.
Returning to Simplicity
Unfortunately, this obesity epidemic is a sad tragedy that is more prevalent among the poor. This is mostly because unhealthy foods are cheap caloric sources. But I also believe we could change the health of America for the better if we started with better education. Organic food may be more expensive, but people on a limited budget don't need to splurge to be healthy. Roasted chicken breasts served with white rice is cheap and way healthier than eating a packaged pizza for dinner. Its small changes like this that can lead us to a more productive and healthier society and help others around the world combat this growing food revolution.