3 Truths and a Lie About Cortisol

Reviewed by Dietitian Jessica Ball, M.S., RD

Key Points

• Cortisol is a hormone that helps manage stress, blood sugar and daily energy patterns.

• A healthy cortisol rhythm includes a rise in the morning and tapering off toward nighttime.

• Consistent under-eating can increase cortisol to mobilize energy during prolonged calorie deficits.

Cortisol has become one of the internet's favorite hormones to blame. Fatigue, visceral fat, appetite changes? Social media is often quick to tell you it's because your cortisol is "too high." That kind of messaging can be compelling because it gives people a clear source to target. But it also conveniently leaves out the necessary—and often beneficial—roles cortisol plays in the body.

Cortisol is an essential hormone that helps your body respond to stress, regulate blood sugar , manage inflammation  and follow a daily sleep-wake pattern . Problems can happen when cortisol levels are too high or too low, but the goal is not to stop cortisol production completely. We spoke with nutrition experts to debunk some of the most common cortisol misconceptions, and explain what actually supports a healthy cortisol pattern.

Truth #1: Cortisol Helps Your Body Get Energy

Cortisol's "stress hormone" nickname focuses on one function while leaving out the everyday jobs your body depends on. "Cortisol is a steroid hormone produced by the adrenal glands, and while it's commonly referred to as the 'stress hormone,' this label understates all of its other functions," says Serena Pratt, M.S., RDN .

One of cortisol's most important jobs is helping your body access energy when demand increases. That demand can come from acute stress, exercise, illness or simply waking up in the morning. Amanda Roll, M.S., RD, CDN , explains that cortisol helps increase glucose availability by supporting gluconeogenesis, the process of making new glucose, and glycogenolysis, the process of breaking down stored glycogen. In plain terms, cortisol helps make fuel available when your body needs to respond to a demand.

Treating cortisol like something to diminish misses the fact that your body relies on it every day for energy production . "When cortisol is rising and falling at the right times and in the right amounts, it's doing exactly what it's designed to do, and the body can't function well without it," says Pratt. The concern only arises when cortisol stays elevated for too long, drops too low or no longer follows an appropriate daily pattern that helps your body function, she explains.

Truth #2: Cortisol Is Supposed to Rise in the Morning

A rise in cortisol after waking is part of your body's normal daily rhythm. It is one way your body shifts out of sleep and into daytime functioning. "Cortisol naturally follows a daily pattern. It begins to rise in the early morning to promote wakefulness and alertness," says Roll. "Levels typically peak within about an hour of waking, then gradually decline throughout the day, reaching their lowest point in the evening to support sleep," she continues. This pattern is called the cortisol awakening response, and research shows that cortisol usually peaks about 30 to 60 minutes after waking, with one study finding that this rise is influenced by the circadian system itself.

Issues can happen when that pattern no longer matches your day. "In a healthy pattern, cortisol rises in the morning to promote wakefulness and alertness, and then falls through the afternoon and evening to promote sleep," says Ryah Nabielski, MS, RDN . Research found that sleep and cortisol closely regulate each other, and sleep restriction  may raise cortisol later in the day. That may explain why chronic poor sleep can become a cycle, since disrupted sleep may affect cortisol timing, and poorly timed cortisol may make it harder to wind down at night.

The goal is not to blunt your normal morning cortisol rise, but rather to support a rhythm where cortisol helps you feel awake earlier in the day and gradually tapers down as your body moves toward rest.

Truth #3: Under-Eating Can Work Against a Healthy Cortisol Pattern

Food restriction is often framed online as a way to "reset" hormones, but under-eating can have the opposite effect on cortisol. Your body needs a steady supply of energy to keep blood sugar within a healthy range. When you go too long without eating or consistently eat less than your body needs, cortisol can rise to help make stored energy available.

Pratt says this is one reason meal timing and adequate intake deserve more attention in the cortisol conversation. "When the body isn't receiving adequate energy from food, it raises cortisol to mobilize stored glucose and prevent blood sugar from dropping too low, essentially treating a calorie deficit as a physiological threat," she says.

That does not mean every missed snack or delayed meal is harmful. The concern is a repeated pattern of underfueling, especially when it is paired with hard workouts or poor sleep. Research shows that cortisol helps maintain glucose availability during stress by increasing glucose production and mobilizing stored fuel. In real life, this may look like replacing a snack with a coffee, skipping breakfast or under-eating after exercise.

Eating consistently enough that your body is not forced to rely on stress hormones to bridge long gaps in energy may help with cortisol regulation, explains Pratt. She recommends eating meals with protein , fiber-rich carbohydrates  and healthy fats  to help support fullness and energy throughout the day.

The Lie: Lower Cortisol Is Always Better

The biggest cortisol myth is that lower is always better. "This is misleading because you don't want to lower cortisol as much as possible," says Roll. "Cortisol is not an inherently 'bad' hormone. It's an essential hormone that supports many normal functions, including regulating metabolism, maintaining blood sugar and helping the body respond to stress."

Pratt says the "lower your cortisol" message often turns into a marketing hook. "The body needs cortisol to function properly, so wanting it as low as possible isn't actually the goal," she says. That is especially important because chronically low cortisol, as seen in Addison's disease  or adrenal insufficiency, can be dangerous.

Cortisol testing can be used to help diagnose or rule out specific adrenal or pituitary conditions , such as Cushing's syndrome, Addison disease and secondary adrenal insufficiency. But cortisol levels vary by time of day, stress, exercise and intake of certain medications, so a single result usually needs clinical interpretation.

That is why experts urge caution with social media claims that assign every symptom to cortisol. "As a dietitian, I encourage being skeptical of any product, test, or piece of content that positions cortisol as the root cause of your symptoms and then conveniently offers a solution, whether that's a supplement, a restrictive diet or a test," says Pratt.

Our Expert Take

Cortisol is not the villain social media makes it out to be. It helps your body access energy, respond to stress, regulate blood sugar and follow a normal sleep-wake rhythm. The goal is not to suppress cortisol as much as possible, but to support a pattern where it rises when your body needs it and tapers down when it is time to rest.

That support often comes from basic health behaviors like eating enough, building balanced meals and sleeping consistently. If you are dealing with persistent fatigue, unexplained weight changes or symptoms that feel out of proportion to your routine, bring them to a health care provider. Cortisol may be part of the conversation, but it is likely not a catch-all explanation for everything going on in your body.

Read the original article on EatingWell