Cortisol – you’ve probably heard of it. It’s that notorious "stress hormone" that spikes when you're knee-deep in a hellish week at work and a nuisance neighbor who blasts 'Baby Shark' at incomprehensible volumes. This steroid hormone doesn't just cater to your daily dose of stress highs, it’s also vital for many bodily functions. Yep, it’s not as villainous as you might think.

What does it do? For starters, it’s like the body's bouncer, regulating blood sugar and aiding metabolic functions. When called upon in times of stress, cortisol is like that friend with a pickup truck – it’s always ready to help you move, turning your fats, proteins, and carbs into usable energy. In a perfect world, cortisol swoops in, boosts your energy to deal with stressful situations, and then dips back down. But in our less-than-perfect reality, chronic stress can jack up cortisol levels, messing with blood sugar and potentially revving up your risk of type 2 diabetes.

Produced by the adrenal glands – two tiny glands on top of each kidney – cortisol jumps straight into your bloodstream. The gear shifters of cortisol production? The pituitary gland and hypothalamus. If things are going the way they should, these small but mighty brain regions supervise cortisol levels, ensuring your body's stress response system runs like a well-oiled machine.

Cortisol levels naturally skyrocket early in the morning and taper off throughout the day. But if your work schedule's more erratic than a roller coaster or you’re a vampire who sleeps during the day, this can throw your cortisol into chaos. Certain health conditions can shrug off the norm too, including adrenal gland disorders that either crank up or dial back cortisol production.

Feeling fatigued all the time? You might be tempted to diagnose yourself with the buzzword "adrenal fatigue." But this trending term lacks science-backed legitimacy. No scientific evidence supports the claim that stress can cause your adrenal glands to belly flop on cortisol production. Quite the contrary, stress is a certified cortisol booster. Neither the Endocrine Society nor any other reputable medical organization recognizes adrenal fatigue as a valid diagnosis.

Brick by brick, we've reached the link between cortisol, metabolism, and weight gain. Chronic stress, with its ever-humming engine of cortisol production, theoretically lends a hand to weight gain. Some studies suggest that excess cortisol could drive us towards high-calorie comfort foods. The science is still out on this one, as human studies have yielded erratic results.

In closing, cortisol is more of a misunderstood ally than an out-and-out enemy, playing a critical role in your body's stress response and overall balance. There’s no use tossing a kale salad at it and hoping for miracles; monitor your stress instead. Remember, we don’t blame the kleenex for the cold, do we?