Genetic Variations, Undereating, Fasting & Why Some Bodies React With Blood Sugar Spikes and Fat Storage
Nov 24
3 min read
Some people can skip breakfast, run on caffeine, fast until noon, hit the gym hard, and feel fine.
Others try the exact same thing and end up anxious, shaky, exhausted, and hungry, yet somehow gain weight despite eating next to nothing.
This isn’t a lack of discipline.
This isn’t “not trying hard enough.”
This is biology—specifically, genetics.
There are certain gene variations—most famously COMT, MAO, DBH, and sometimes MTHFR—that make it harder for the body to break down and clear catecholamines, which are your adrenaline-family stress chemicals.
For someone with these variants, adrenaline doesn’t shut off efficiently.
The result? A body that stays in a prolonged stress state long after the stressor is gone. And here is where the standard diet culture advice goes entirely off the rails.
🍽 Undereating and Fasting Are Not Neutral For These Bodies
When someone with slow catecholamine clearance skips meals, fasts too long, or undereats, their blood sugar drops rapidly.
A normal body would release a measured amount of cortisol to stabilize blood glucose levels.
But a slow-clearance body? It releases a flood.
Cortisol spikes → raises blood sugar too high → followed by a crash → which forces another cortisol spike.
This roller coaster becomes the dominant metabolic rhythm.
And what does that create?
Adipogenesis!Fat creation.
Storage mode.Especially around the midsection, hips, and thighs.
Not because someone “overate.”
But because their cortisol–glucose loop was activated all day long by undereating.
🍩 Blood Sugar Spikes With No Food? Yes.
People with these genetic patterns often experience glucose spikes even after “healthy” or “tiny” meals because cortisol is doing the work of an entire pancreas.Fasting may make this worse, not better.
This is why so many women say:
“I gain weight when I fast.”
“I feel like I’m swelling after a workout.”
“I get dizzy when I skip meals.”
Their genes explain it.
🔥 Vigorous or Long Exercise Makes It Even Worse
High-intensity or long-duration exercise increases catecholamine levels.
If you can’t clear them efficiently?
You get:
• migraines
• panic
• dizziness
• post-exercise crashes
• delayed-onset anxiety
• trouble sleeping
• borderline hypoglycemic episodes
• inflammation
• fat storage instead of fat burning
The fitness world calls this “overtraining.” But for someone with these genetics, it’s not overtraining—it’s regular exercise colliding with a unique biochemistry.
And that difference matters.
🌙 Perimenopause Amplifies Everything
Females are different.Period.
As estrogen fluctuates wildly, insulin sensitivity becomes unpredictable.
Combine this with slow catecholamine clearance, and you get:
• massive blood sugar swings
• sudden weight changes
• worsening anxiety
• hot flashes triggered by cortisol
• insomnia
• inflammatory patterns
• thyroid slowing
• pelvic instability
This is not “hormone imbalance.”
This is a symphony of stress chemistry that never turns off.
🧬 These Genetics Appear Across a Lifetime
Before perimenopause, you’ll often see:
• migraines
• anxiety
• depression
• ADHD
• bipolar tendencies
• panic attacks
• chronic fatigue
• hypothyroidism
• autoimmune tendencies
• certain cancer predispositions (via impaired methylation)
It’s not random.
It’s not “just who they are.”
It’s a nervous system running hot, genetics that magnify stress chemistry, and physiology that was never meant to be shoved into one-size-fits-all diet or exercise protocols.
🎯 Why the Standard Advice Fails
Most mainstream diet and exercise science is:
• male-dominated
• young-body-centric
• assumes rapid catecholamine clearance
• assumes stable insulin
• assumes morning cortisol resilience
• ignores the menstrual cycle
• ignores perimenopausal physiology
• ignores genetic individuality
This means the “gold standard” strategies— fasting, keto, HIIT-heavy programs, low-calorie diets, long-duration cardio—They are often the worst possible match for the very people seeking healing.
People with slow catecholamine clearance don’t thrive in deprivation. Their nervous system needs rhythmic fuel, not stress stacking.
