Fasting has long been celebrated as a powerful tool for reducing inflammation and promoting metabolic health.
But emerging research suggests there’s a hidden catch that could be undermining these benefits.
The issue centers around cortisol—the stress hormone that spikes during fasting and may not be turning off when it should.
Health and fitness expert Thomas DeLauer recently broke down why chronically elevated cortisol from fasting could actually increase inflammation, and more importantly, how to fix it with a surprisingly simple strategy.
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The Cortisol Paradox: Why Fasting Raises Stress Hormones
During a fast, insulin levels drop significantly because no food—especially carbohydrates—is coming in. Without insulin’s presence, the body needs another mechanism to maintain blood sugar levels and keep energy available.
Enter cortisol. This stress hormone triggers glucose release from the liver and muscles, essentially keeping you alive and functioning during periods without food.
There’s a reason that cortisol is high when we fast. We just have to know how to capitalize on it and when to completely shut it down.
While fasting, elevated cortisol actually helps with fat burning. The problem emerges when cortisol remains elevated long after the fast ends or becomes chronically high from consistent fasting practices.
When Cortisol Becomes The Enemy
A study published in Endocrinology and Metabolism examined various fasting protocols—alternate day fasting, the 5:2 approach, and different forms of time-restricted eating. Researchers found that while many hormones fluctuate during fasting, cortisol consistently remained elevated across all methods.
Even more concerning, this elevation often persisted around the clock, creating a carryover effect that extended well beyond fasting windows.
The Inflammation Connection
Chronically elevated cortisol creates inflammation through multiple pathways. High circulating glucose from sustained stress responses damages tissues over time. But the deeper issue is that perpetually elevated cortisol signals chronic stress to the body.
Chronic stress ranks among the leading causes of inflammation worldwide. It’s also a primary driver of visceral fat accumulation—the dangerous fat that wraps around internal organs.
Cortisol plus insulin or cortisol plus fat is the deadly combination that leads to massive fat accumulation, massive visceral fat accumulation, and chronic inflammation left and right.
A 2021 study published in Nutrients analyzed 14 different fasting studies, from Ramadan fasting to various intermittent fasting protocols. The common denominator wasn’t just high cortisol—it was dysregulated cortisol rhythms.
People experienced inappropriate cortisol spikes at 4:00 a.m., followed by crashes later in the day. This disruption undermines the natural circadian rhythm that cortisol should follow.
The Simple Solution: Strategic Carbohydrate Timing
The answer might sound counterintuitive for those deeply invested in low-carb or ketogenic approaches. But there’s one hormone powerful enough to shut down cortisol production: insulin.
When the body detects insulin—primarily triggered by carbohydrate intake—it signals the hypothalamus that fuel is available. This communication cascade travels through the pituitary gland to the adrenals, essentially telling them to turn off cortisol production.
How Much and When?
The strategy involves consuming 20 to 50 grams of carbohydrates at the end of a fasting window. This small insulin spike effectively shuts down the cortisol loop without causing significant fat storage—especially when done without excess calories.
We’re talking about strategically adding carbohydrates in the absence of additional calories to turn off the cortisol response.
Good carbohydrate sources for this purpose include:
- Honey – easily digestible with rapid insulin response
- Molasses – provides minerals along with carbohydrates
- Fruit – whole food option with fiber
- Rice or potatoes – for those preferring starch-based options
The Mid-Fast Carbohydrate Trick
Perhaps most surprising is the suggestion that small amounts of carbohydrates during a fast won’t completely destroy its benefits. If cortisol feels excessively elevated 15 hours into a 20-hour fast, consuming one to two tablespoons of honey creates a temporary insulin spike that quickly subsides.
This approach can actually increase metabolic rate and fasting effectiveness through mechanisms involving FGF-21 (fibroblast growth factor 21), a hormone that plays a role in metabolic regulation.
This isn’t meant to be done routinely—only when stress levels feel particularly elevated during an extended fast.
When You Actually Want High Cortisol
Not all cortisol elevation is problematic. Morning cortisol spikes are beneficial and natural. This early surge provides energy, mental clarity, and enhanced fat oxidation—particularly valuable before morning workouts.
The goal isn’t to eliminate cortisol but to optimize its timing. Problems arise when cortisol remains elevated during inappropriate times—mid-afternoon, evening, or throughout the night.
You do burn more fat when cortisol is high. And that’s where people get lost. They think cortisol is all bad. They think insulin is all bad. Cortisol can help us. And insulin can help us, too.
By shutting down cortisol at the end of a fast with strategic carbohydrates, natural cortisol rhythms can maintain their beneficial patterns without chronic elevation.
Additional Strategies For Managing Stress and Inflammation
Beyond carbohydrate timing, several supplements can help manage cortisol and inflammation during periods of high stress or intensive fasting:
N-Acetylcysteine (NAC)
Taking 300 to 600 mg of NAC supports glutathione production—the body’s master antioxidant. This provides cellular tools to combat oxidative stress and inflammation during metabolically demanding periods.
Magnesium
Quality forms like magnesium glycinate or dimagnesium malate (400-500 mg) offer benefits for stress reduction, cortisol management, insulin sensitivity, and direct anti-inflammatory effects.
Tryptophan
Evening doses of 500 to 1,000 mg help produce serotonin and melatonin, shifting the nervous system toward parasympathetic (rest and digest) tone rather than remaining in sympathetic (fight or flight) overdrive.
Spermidine
This compound promotes autophagy—cellular cleanup and recycling—even on higher calorie days. It’s particularly useful when reducing fasting frequency to manage stress while maintaining some metabolic benefits.
Black Seed Oil
One of the most potent natural anti-inflammatory compounds available. Use it sparingly, as tolerance can develop quickly with continuous use.
Glycine for Sleep
This amino acid functions as a calming neurotransmitter, improves sleep quality, and reduces nighttime urination—all factors that influence cortisol regulation and recovery.
The Balanced Approach
Fasting remains a powerful metabolic tool with proven benefits for inflammation, autophagy, and metabolic health. But like any intervention, it requires strategic implementation.
The key isn’t avoiding fasting or carbohydrates entirely—it’s understanding how to use both strategically. By breaking the chronic cortisol cycle with small, well-timed carbohydrate intake, fasters can maintain the anti-inflammatory benefits while avoiding the pitfalls of dysregulated stress hormones.
Good sleep and controlled cortisol levels work hand in hand. Without addressing one, the other remains compromised. This integrated approach—combining smart fasting protocols, strategic carbohydrate timing, and targeted supplementation—offers a more sustainable path to metabolic optimization without the inflammatory consequences of chronic stress.
