You can view eating in the modern world as a life-or-death matter. Protracted poor eating leads to unwanted weight gain that increases the likelihood of obesity, diabetes, heart disease, certain cancers, Alzheimer's disease, and depression all of which can lead to your demise.

Eventually.For prehistoric man eating was also a life-or-death matter but not eventually.Immediately.Every time he needed to hunt a large animal to feed himself and his clan, it was kill or be killed. Talk about a stressful meal preparation.To counteract such stress and enhance physical performance, thereby increasing the chances of a kill or a successful escape from one gone bad the body learned to produce adrenaline and cortisol. The secretion of these hormones immediately boosts sugar and oxygen levels in the bloodstream, instantly increases alertness, and creates a crazy surge of energy.How crazy? The type of surge that once allowed a petite grandmother to deadlift the back end of her station wagon once she realized what she had just backed over in the driveway was her three-year-old granddaughter. Your body also has the ability to produce these two hormones in times of stressbut consider what now causes you stress.Hunting? Most modern food hunting is done with a shopping cart and a credit card. And if do you roam the woods with a rifle or a bow and arrow, that's usually considered a form of recreation and rarely a situation of life or death.The worst modern stress is mental. It comes from dealing with work deadlines, less-than-cooperative people, or the expectations you place upon yourself.The stress is not physical, yet it still creates the release of adrenaline and cortisol. While this helps you better handle your job or a jerk, it hurts your body eventually.Physical effort is needed for your body to properly absorb and process adrenaline and cortisol. Without it, these hormones that amp you up plump you up.Think about it.Stored fat is stored energy, albeit slow burning. Glycogen, carbohydrate energy stored in the cells, burns far quicker and is what your body uses for the quick, deft, and powerful movements required to battle a big, man-eating animal with only a sharpened rock and savage hands.As a result, the body knows to stop burning fat whenever adrenaline and cortisol are secreted. And when fat burning stops and glycogen raises blood glucose levels, the body secretes another hormone, insulin.As you well know, insulin's job is to escort glucose from the bloodstream to the muscle cells or the fat stores.But when you secrete adrenaline and cortisol because of mental stress, your muscles don't use any energy, so they reject the new glucose. Your fat stores, unfortunately, aren't that discriminating.They'll store excess energy just about anytime.So in a sense, stress can make you fat. Eventually.Even the type of internal stress created by a diet.A study lead by Janet Tomiyama, a Robert Wood Johnson foundation scholar at the University of California-San Francisco, assigned 99 women to one of four groups. Two of the four groups consumed only 1,200 calories a day, one didn't diet but counted calories, and one didn't diet or count calories.By testing the subjects' saliva, the researchers found that the dieters had higher levels of cortisol in their bodies during the three-week study than the non-dieters.While the dieters still lost an average of two pounds, the increase in cortisol indicates that the weight loss may only be temporary since most people don't have the ability to fight that I'm-so-hungry feeling that comes with dieting forever.And by triggering the release of insulin, the release of cortisol eliminates enough blood sugar to create that I'm-so-hungry feeling.So what's a dieter or anyone who regularly encounters mental stress supposed to do? What prehistoric man did after producing adrenaline and cortisol.Expend energy. But don't attempt to slay a saber-toothed tiger with a baseball-sized rock and your bare hands. Exercise.A 2012 University of Maryland study published in Medicine and Science in Sport and Exercise gave healthy, college students the State-Trait Anxiety Inventory, a test used to determine stress level and then had them cycle at a moderate intensity for 30 minutes. Fifteen minutes after the exercise, the subjects took the test again. They took the test a third time after being shown a series of very pleasant, very unpleasant, and neutral photographs, "designed to stimulate," according to Carson Smith, an associate professor at the college, "the range of emotional events you might experience in daily life."The series of tests were administered and the photos were shown again to the subjects on another day when they did not cycle.The findings of the testing shows that the exercise helped the subjects better initially handle the stress brought on by viewing the unsettling photographs.