Remember poor Morgan Spurlock, eating nothing but McDonald’s for a month in his documentary Super Size Me? As meal followed meal, lubricated with gallons of Big Gulps, he became fatter, his liver turned to a greasy mush, and he felt simply terrible. If you listened carefully to the voiceover, he also sounded fatigued…and depressed.
Now researchers reporting in the British Journal of Psychiatry confirm what many clinical nutritionists have known all along–that a diet of junk food can indeed trigger clinical depression. Scientists tracked the eating habits of 3,500 middle aged public servants (a decidedly British categorization) for five years, splitting them into two groups: those who ate primarily a junk-food/fast-food diet (processed foods, high in fat, refined carbs, and sugar) and those who ate reasonably close to a whole-food diet (high in fruit, veggies, fish, and whole grains).
The results of the study are enough to make you think twice before stifling your hunger pangs with any of the dozens of junky menu items that many Americans eat every single day of their lives.
Junk-food eaters had a 58% higher risk of depression, while the depression risk for whole-foods eaters was 26% lower. That’s an impressive spread.
The physiology behind this goes back to the brain chemical serotonin, your factory installed stress-buffering system and the second whammy I wrote about in The Triple Whammy Cure (the other two being stress itself and hormones).
In order for your body to make feel-good serotonin, you need a steady supply of good quality protein. Why? When protein is digested, it breaks down into amino acids, one of which is tryptophan. Your body then converts tryptophan into serotonin.
In an earlier study, people deliberately placed on a low-tryptophan diet developed depression, which reversed itself when tryptophan was reintroduced.
A fast food diet, decidedly high in fats but low in high-quality protein (such as fish, eggs, and lean meats, but also beans, rice, corn, and wheat), will grind serotonin production to a halt. Life stresses will occur, as they always do, but with no adequate stress buffer, you’ll feel anxious, depressed, tired, and generally miserable. One of the stressors is hypoglycemia (low blood sugar), also a consequence of eating junky food with scant nutritional value.
This mess soon spins out of control, your brain becomes desperate for a quick fix, and as a result you make a serious judgment error. You start craving more junk foods for the quick carb/sugar high. You gain weight and become even more depressed.
You don’t have to pull a Morgan Spurlock and try this fast-food diet on yourself. Just go into any McDonald’s, Wendy’s, Taco Bell, or Pizza Hut–any of them. Buy a bottle of water and just sit where you can watch people walk in. Direct your attention to the body shapes, complexions, and facial expressions of the adults. Note the kids may have little pot bellies and double chins, but anticipating free toys may look cheerful. Sit there long enough and you’ll want to start screaming, “Save yourselves! Get out of here before it’s too late!”
Remember you’re just there to observe. Finish your water, get thee to the grocery, go home, and cook up a nice pot of the minestrone soup we’re featuring as today’s healthy recipe. Pack the leftovers for future lunches. You’ll be healthier and happier as a result.
David Edelberg, MD