"Don't live your life on autopilot. Be conscious of all you do and aware of how the all affects you."

If you asked me to create a clever quotation of 20 words or less to serve as a beacon for better living and better health and fitness, that's what I'd say to you.

Today, the speed and scope of life are such that too often we're required to respond instantly rather than ruminate thoughtfully. We resort to convenience, habit, and pattern to direct our actions and quickly move on to the next thing to do.

Living like this makes it easy to forget that actions do not occur in a vacuum, that there's a domino effect to all we do.

For instance, a bad diet can lead to more than a belt-lapping belly or fat-dimpled thighs. Being overweight also increases your risk of developing such diseases as diabetes, heart disease, stroke, osteoarthritis, sleep apnea, and certain cancers while increasing your overall chance of dying young.

But chances are you knew all that, so today's column will focus on something else.

A bad diet, for lack of a better phrase, can mess with your mind.

Whether it be your immediate mental state or cumulative brain damage, a number of recent studies have shown just that.

For about the last dozen years, the American public has been made well aware of the physical problems that the use of trans fat creates. In fact, just about all research comparing trans fat to saturated fat, the so-called "bad" fat, finds trans fat to be worse.

One study done by Dutch researchers, for example, had healthy subjects either eat a diet high in trans fat or saturated fat for four weeks and then switch diets for the same amount of time. The researchers found that after four weeks of the trans fat diet subjects had 20 percent less HDL, the good cholesterol for heart health, and less vascular elasticity than when compared to the saturated fat diet. Other studies have found a correlation between trans fat ingestion and an increase in LDL, the "bad" type of cholesterol that blocks arteries and causes heart attacks.

But according to a recent Spanish study of more than 12,000 men and women, trans fat could do more than increase your risk of heart trouble. It could make you depressed as well.

Researchers used a 136-item food-frequency questionnaire to determine just how much trans fat the subjects were ingesting. Even though Spaniards eat relatively little trans fat on the whole, those recording the highest amounts were 42 percent more likely to have developed depression during the course of the six-year study.

Considering that the typical American ingests six times the amount of trans fat as the typical Spaniard, is it really any surprise that depression in American children has recently increased by 23 percent and that nearly 10 percent of adults suffer from a depressive disorder in any given year? But what's even more frightening about these statistics is that 60 percent of those who commit suicide are at the time suffering from some sort of depressive disorder like depression.

Bipolar disorder, a mental disorder marked by alternating periods of elation and depression, has also been on the rise in the U.S. recently, and it has also been linked to bad diet.

A study first presented at the British Association for Counseling & Psychotherapy's annual conference showed that taking vitamins and minerals especially vitamin B, magnesium along with eating a healthy diet high in omega-3 fatty acids and low caffeine and sugar minimized the intensity and frequency of mood swings in those suffering from bipolar disorder. Interestingly, what the presenters deemed "erratic eating" a dramatic increase or decrease in consumption, enough to alter a sufferer's nutritional profile is characteristic of bipolar disorder episodes.

A bad diet can also affect the physical workings of the brain and create long-term damage. A report in the June issue of Archives of Neurology found that the sort of bad diet associated with type 2 diabetes, a diet high in simple carbohydrates and saturated fat, also increased the biomarkers consistent with Alzheimer's disease. In subjects not already suffering from cognitive impairments, a diet low in simple carbs and saturated fat decreased these biomarkers, as well as total cholesterol.

The authors deemed these results so significant that they wrote "the therapeutic effects of [diet] may be a promising avenue of exploration" in the attempt to battle Alzheimer's.

Similarly, a 2011 Rush University Medical Center study found that the Mediterranean diet, long reputed for helping heart function while reducing the risk of cancer, also reduces the likelihood of developing Alzheimer's disease.