It's not as if you haven't heard the reasons before.

In one of the first bestselling books to bad mouth the sweet stuff, Everything You Always Wanted to Know About Nutrition (1978), Dr. David Reuben explains that your body strives to have 100 milligrams of glucose (the form most sugars and simple carbohydrates take in the body) in every 100 milliliters of blood.That's one thirtieth of an ounce in every quart of blood. Since there are six quarts of blood in an average-sized male, the amount of sugar that you optimally need at any time in your blood stream is about one fifth of an ounce.Which is six times the amount in the typical 12-ounce soda.Reuben also reveals how closely related chemically table sugar is to cocaine and suggests that's why people get hooked on it.Research published in 2002 provided proof that sugar can be as addicting. Princeton University researchers fed laboratory rats a solution of 25 percent glucose and 10 percent sucrose along with their normal food for eight days. On the ninth day, they took the solution away.The rats grew anxious, chattered their teeth. When they were again permitted the sweet mixture, they consumed larger quantities than before.In other words, the rats resembled strung-out junkies who finally made a score.In later experiments, the Princeton researchers learned more by studying the brains of rats after they ingested large amounts of sugar and the brains of rats that received cocaine. Both triggered the release of the neurotransmitter dopamine, which regulates the brain's reward and pleasure centers.Dopamine also helps regulate emotional responses, often causing you to seek pleasurable rewards and take action to get them. While a dopamine deficiency can result in Parkinson's disease, it's even more likely to cause an addiction as you continually use the substance that produces its release.This type of addiction is what a study presented at the 2013 Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging suggests occurs to some degree to the estimated 26 million Americans who have insulin resistance from type 2 diabetes and the 79 million more who have it from metabolic syndrome, a precursor of diabetes. They overeat and gain weight because it's that pleasurable release of dopamine that they're looking for from sugar and the overly processed simple carbs that quickly break down into sugar.Lead author Gene-Jack Wang, professor of radiology at Stoney Brook University, said this about his research team's findings: "We suggest that insulin resistance and its association with less dopamine release . . . might promote overeating to compensate for this deficit . . . . This [discovery] may be the link we have been looking for between insulin resistance and obesity."Other research suggests that dopamine secretion or lack thereof affects actions.Research published in the May issue of The Journal of Neuroscience reported that subjects who displayed a lesser response to dopamine in what's called the reward and motivation areas of the brain were more likely to pass on the chance to make money if they perceived the effort to be too great when compared to the subjects who displayed a greater dopamine response. In fact, those displaying the higher response even accepted opportunities when they clearly had low odds of success, suggesting perhaps that the dopamine response creates optimism.The results of this study lead dopamine expert Marco Leyton, Ph.D. and teacher at McGill University to state in an article by Medical News Today that "abnormal dopamine transmission could affect a wide range of decision-making processes and susceptibility to depression."I shared the dopamine research with you in order to plant a seed in you. Could this abnormal dopamine transmission be what makes it so hard for you to stick to a healthy diet after one that includes sugary junk?While I don't think there's enough research to state that for certain, there is enough research and anecdotal evidence to make this claim: Eating has to be more than just a way to eliminate hunger and gain pleasure.That's because what you eat and when you eat and how much you eat all influence something even more important than the circumference of your waistline and your appearance.These aforementioned variables affect your short-term and long-term health often by causing your body to secrete more or less of certain hormones.So become attuned to how your body functions and how you feel when try new foods, a different eating time, or an entirely new diet. Note these changes and remember this anonymous but astute quotation: "You never know, that's why you feel."