What Metabolic Syndrome Is, Why It's Affecting Nearly 1 in 3 Americans, and What You Can Do About It
Metabolic Health Series | Issue 01
I want to start this series with something that genuinely surprised me when I first dug into the research: more than one-third of American adults currently meet the criteria for metabolic syndrome. Most of them have no idea. Their labs came back "normal." Their doctor didn't flag anything. They just feel a little tired, a little heavier than they used to be, a little off.
That gap — between what's happening metabolically and what gets named and addressed — is exactly why I wanted to write this series. So let's start at the beginning.
What Is It, Exactly?
Metabolic syndrome isn't a single disease. It's a cluster of five interconnected abnormalities that, together, dramatically raise the risk of type 2 diabetes, cardiovascular disease, stroke, and fatty liver disease.
A diagnosis requires at least three of these five:
Waist circumference above 40" (men) or 35" (women)
Triglycerides at 150 mg/dL or higher
HDL cholesterol below 40 mg/dL (men) or 50 mg/dL (women)
Blood pressure at 130/85 mmHg or higher
Fasting blood sugar at 100 mg/dL or higher
Three out of five. That's the threshold. And you can meet all five and feel, by most ordinary measures, perfectly fine.
The Numbers
Metabolic syndrome affected roughly 28% of American adults in 1999. By 2018 it had climbed to nearly 37% — and the trend hasn't reversed. By age 60, approximately 40% of Americans meet the criteria.
This is not a niche clinical concern. Researchers have called it a metabolic pandemic — driven not primarily by genetics, but by the food systems we've normalized and the daily habits most of us inherited without question.
How It Develops
At the center of metabolic syndrome is insulin resistance — and understanding it changes how you see almost everything else in this space.
When you eat, blood sugar rises, insulin is released, and cells absorb glucose for energy. The problem begins when cells, overwhelmed by chronically elevated blood sugar, start to resist that signal. The pancreas compensates by producing more insulin. For a while, this works — blood sugar stays controlled, but insulin is running dangerously high in the background.
Biochemist Ben Bikman has made a compelling case that this state — hyperinsulinemia — isn't just a symptom of metabolic dysfunction. It's one of its primary drivers. Chronically elevated insulin promotes abdominal fat storage, raises triglycerides, suppresses HDL, and increases blood pressure. In other words: it drives nearly every criterion on the metabolic syndrome checklist.
Left unaddressed, this cascade progresses toward prediabetes, then type 2 diabetes. But here's what matters most: insulin resistance is reversible. For the vast majority of people, this is not a permanent state.
Risk Factors Worth Knowing
Diet — ultra-processed foods, refined carbohydrates, and added sugars (particularly fructose) are the primary dietary drivers. Robert Lustig's research on how fructose overloads the liver and accelerates metabolic dysfunction is worth understanding deeply — we'll get into it in Issue 2.
Inactivity — skeletal muscle is the body's primary site of glucose disposal. When it's underused, we lose our most powerful metabolic buffer.
Poor sleep — even a few nights of inadequate rest measurably degrades insulin sensitivity, elevates cortisol, and disrupts appetite hormones. Matt Walker's research on this is striking (more in Issue 7).
Chronic stress — cortisol raises blood sugar, promotes visceral fat, and blunts insulin sensitivity. When stress is chronic, the metabolic consequences compound.
Age — risk rises with age, driven by shifts in body composition and declining hormonal function.
The Symptoms Most People Miss
Metabolic syndrome is "silent" because it rarely announces itself dramatically. What it does instead is produce signals we tend to normalize:
Fatigue and energy crashes after meals
Stubborn weight gain around the abdomen
Intense carbohydrate cravings
Brain fog and difficulty concentrating
Skin tags or darkening in skin folds — a direct marker of elevated insulin
Elevated thirst and frequent urination as blood sugar trends higher
If several of these sound familiar, that's worth paying attention to.
The Diagnostic Gap
What’s frustrating is the standard blood panels ordered in routine physicals often miss early metabolic dysfunction entirely. Fasting glucose is the last marker to become abnormal — by the time it's elevated, insulin resistance has typically been present for years.
A more useful picture comes from asking your doctor for:
Fasting insulin (rarely ordered, and more informative than HbA1c or fasting glucose)
HOMA-IR — calculated from fasting glucose and insulin; a sensitive early indicator
Triglyceride-to-HDL ratio — a strong proxy for insulin resistance; below 2.0 is favorable
Waist-to-height ratio — more predictive than BMI; below 0.5 is generally healthy
Knowing the right numbers is the first act of metabolic self-advocacy.
The Good News: It's Largely Reversible
A 2024 analysis of 98 randomized controlled trials confirmed what functional nutrition practitioners have observed for years: combined nutrition and lifestyle interventions can reverse metabolic syndrome criteria — often within months.
The interventions with the strongest evidence:
Reducing ultra-processed foods, refined carbs, and added sugar
Prioritizing whole foods — quality protein, fiber, vegetables, and healthy fats
Building and maintaining muscle through resistance training
Protecting sleep as a non-negotiable metabolic benefit
Managing chronic stress — not as a soft lifestyle add-on, but as a physiological necessity
Sami Inkinen, the researcher/Ironman/entrepreneur who reversed his own prediabetes through dietary change, put it plainly: metabolic health is not a fixed biological destiny. It's a function of daily habits. And the body, given the right conditions, responds faster than most people expect.
Three Things to Do This Week
Ask for fasting insulin at your next lab draw — not just fasting glucose. If your doctor isn't familiar with HOMA-IR, bring it up.
Calculate your waist-to-height ratio. Measure at the navel, divide by your height (same units). Above 0.5 warrants attention.
Track your energy for three days. Note when you crash, when you crave carbs, when your thinking gets foggy. Your body is already giving you data.
Next issue: "Sugar, Insulin, and the Slow Burn" — Robert Lustig's case against fructose, Ben Bikman on hyperinsulinemia, and what the modern diet is actually doing to your metabolism.
This newsletter is educational and does not constitute medical advice. Work with a qualified healthcare provider for personalized guidance.
Do any of these metabolic syndrome symptoms sound familiar?
I’d love to help you sort it all out, and get you back to optimal health.
Lisa Marlene Thompson is a Functional Nutritional Therapy Practitioner, somatic facilitator, and health guide for anyone ready to feel more alive in their body. With advanced certifications in menopause science with Dr. Stacy Sims, somatic movement with Michaela Boehm, and sleep and brain health informed by the research of Lisa Mosconi and Matt Walker, her work sits at the intersection of cutting-edge science and deep body wisdom.
Her signature program — Strength, Sleep & Sensuality — is an invitation to come home to your body: to build real strength, reclaim restorative sleep, and rediscover a nervous system that is grounded and provides aliveness in the body that belongs to this chapter of life. She is based in Los Angeles and works with clients worldwide.
Your most vibrant chapter is still ahead.
I'd love to explore what's possible together → Reach out: lisa@lisamarlenethompson.com