Why Are Americans So Unhealthy? The 6 Root Causes

The numbers are stark and they don't improve with optimism.

Forty-two percent of American adults are obese. Ninety-six million have prediabetes. Cardiovascular disease kills one in five Americans. Life expectancy — which climbed steadily for most of the 20th century — has been declining since 2015 in what researchers call "deaths of despair" combined with metabolic disease. The U.S. spends more per person on healthcare than any country on earth and produces some of the worst outcomes among wealthy nations.

The standard answer is "people make bad choices." That answer is incomplete and, in many ways, designed to deflect from structural causes.

This piece covers the actual root causes — the systems, policies, and products that created the health crisis — without moralizing about individual behavior.

The Scope of the Problem

Before diagnosing causes, the scale deserves clear statement:

• Obesity: 42.4% of adults (CDC 2020), up from 30.5% in 2000 and 15% in 1980
• Metabolic syndrome (a cluster of conditions including high blood pressure, high blood sugar, excess abdominal fat, and abnormal cholesterol): affects roughly 1 in 3 American adults (NIH data)
• Type 2 diabetes: 37.3 million Americans, 96 million with prediabetes (CDC, 2022)
• Heart disease: Leading cause of death, 695,000 deaths annually
• Healthcare cost: $4.1 trillion annually — 17% of GDP — the highest proportion of any developed nation

These conditions share a common metabolic thread: they're driven primarily by diet quality, physical inactivity, sleep disruption, and chronic stress. They are largely preventable. And yet they keep getting worse.

📖 Related: Learn more about the movement at MAHA Fitness: The Complete Training Philosophy, How to Join the MAHA Movement: A Citizen's Guide, and Chronic Disease in America: State-by-State Statistics.

Root Cause #1: The Rise of Ultra-Processed Food

The most significant driver of American metabolic disease is the near-total replacement of whole foods with industrial food products.

The NOVA classification system, developed by epidemiologist Carlos Monteiro at the University of São Paulo, classifies foods by degree of processing. Ultra-processed foods (UPF) are industrial formulations containing ingredients rarely found in home kitchens — emulsifiers, artificial flavors, synthetic colors, textured vegetable proteins, and stabilizers designed to extend shelf life and engineer palatability.

According to research published in Population Health Metrics, ultra-processed foods now account for 57% of caloric intake for average American adults and 67% for American children. A 2019 NIH clinical trial30248-7) — the first randomized controlled trial of ultra-processed food consumption — found that participants eating ultra-processed diets consumed an average of 500 more calories per day compared to minimally processed diets, even when both groups had equivalent access to nutrients. They gained weight on UPF diets and lost weight on whole food diets.

Ultra-processed foods share characteristics that explain this:

• Engineered palatability: "Bliss point" formulations that stimulate reward pathways beyond what whole foods trigger
• Low satiety signaling: Processed out fiber and protein that would normally trigger fullness
• Rapid glycemic load: Refined carbohydrates spike blood glucose quickly, driving insulin response and subsequent hunger
• Micronutrient displacement: Calories without the vitamins, minerals, and phytonutrients that whole foods provide

Read the complete MAHA guide to seed oils →

Root Cause #2: Industrial Seed Oils

One specific category of ultra-processed ingredient deserves separate treatment: seed oils.

Soybean oil, corn oil, canola oil, sunflower oil, cottonseed oil, and safflower oil are collectively the dominant cooking and food-preparation fats in the American diet. Per capita consumption of these oils increased by roughly 1,000% between 1900 and 2000, according to data analyzed by researcher Stephan Guyenet in his book The Hungry Brain and supported by USDA food supply data.

The biochemical concern: these oils are extremely high in linoleic acid, an omega-6 polyunsaturated fatty acid (PUFA). PUFAs oxidize at cooking temperatures, producing aldehydes and lipid peroxidation byproducts. Research published in Free Radical Biology and Medicine has documented elevated oxidative stress markers associated with high linoleic acid intake.

The omega-6 to omega-3 ratio has shifted dramatically. Traditional human diets maintained roughly a 4:1 ratio. Modern Americans average 15:1 to 20:1. This imbalance is associated with chronic inflammatory states — a background condition that underlies virtually every major chronic disease.

A 2020 analysis in Academic Press found that linoleic acid now comprises approximately 21% of total energy in the average American diet, up from less than 2% in 1900. This represents the single largest change in the American food supply over the past century.

Root Cause #3: Sedentary Work and Life

Human bodies evolved for sustained physical activity. The ancestral human — as documented in anthropological research on remaining hunter-gatherer populations — walked 8–15 miles daily, carried heavy loads, engaged in frequent lifting and climbing, and rested intermittently throughout the day rather than sitting for extended blocks.

The modern American adult sits for an average of 6.5 hours per day, according to CDC data. Office workers may sit for 10 or more hours including commutes. This isn't just absence of exercise — prolonged sitting has independent metabolic effects distinct from low overall activity.

Research published in Diabetologia found that even in active individuals, prolonged uninterrupted sitting is associated with increased blood glucose, decreased insulin sensitivity, and elevated triglycerides. The mechanism involves impaired muscle contraction — muscle activity is required to clear glucose from the bloodstream effectively, and inactive muscles don't do this job.

The modern built environment compounds this. American cities and suburbs were designed around automobile transportation, not pedestrian or cycling infrastructure. The average American suburb makes walking for daily errands physically impractical. Getting to work, to food, and to social activity requires a car — and cars require sitting.

Root Cause #4: Agricultural Subsidies Distorting the Food Market

American food prices don't reflect real production costs — they reflect a century of policy decisions that artificially subsidized some foods and ignored others.

Federal commodity crop subsidies totaling over $20 billion annually flow primarily to corn, soybeans, wheat, cotton, and rice. These crops form the raw inputs for most ultra-processed food: high-fructose corn syrup, soybean oil, refined wheat flour, corn starch. By making these ingredients artificially cheap, subsidies make ultra-processed food artificially cheap.

A 2019 JAMA Internal Medicine analysis found that subsidized food commodity consumption was associated with higher rates of cardiovascular disease, inflammation, and metabolic dysfunction. Research from the Physicians Committee for Responsible Medicine has documented that fruits and vegetables — the foods dietary guidelines most consistently recommend eating more of — receive less than 1% of commodity subsidies.

The result is a price structure that's backwards from a public health perspective: a bag of corn chips often costs less than a pound of broccoli. A fast food meal for a family of four may cost less than a grocery run for real ingredients. For lower-income Americans, this isn't a "bad choices" problem — it's a market structure problem.

Root Cause #5: Food Marketing, Especially to Children

The food industry spends approximately $14 billion annually marketing food and beverages in the United States, according to the Federal Trade Commission. A disproportionate share targets children.

A 2021 JAMA Pediatrics study found that food marketing exposure is associated with increased preference for and consumption of advertised (primarily ultra-processed) products. Marketing works — particularly on children whose prefrontal cortex, responsible for impulse control and long-term thinking, is still developing.

The marketing is sophisticated. Products are positioned as fun, aspirational, social, and energizing. Mascots and cartoon characters build brand loyalty in preschool-aged children. Celebrity endorsements and social media influencer campaigns reach adolescents. The nutritional reality of the products being marketed is rarely germane to the pitch.

School food environments have improved incrementally under federal guidelines, but ultra-processed food remains standard in most American school cafeterias. Children who grow up eating ultra-processed food develop taste preferences calibrated to high sugar, high salt, and high fat combinations — preferences that persist into adulthood and make whole food adoption harder.

Root Cause #6: Sleep Deprivation

Sleep is a metabolic function, not just rest. This fact has been underappreciated in public health messaging focused almost entirely on diet and exercise.

The CDC reports that more than one-third of American adults regularly get less than 7 hours of sleep. Research from the University of Chicago found that sleep deprivation disrupts ghrelin and leptin — the hormones that regulate hunger and satiety — increasing caloric intake by an average of 300 calories per day in sleep-deprived subjects.

Chronic sleep deprivation also impairs insulin sensitivity (comparable to the effect of a high-fat diet in some studies), elevates cortisol, and promotes fat storage — particularly visceral fat around the abdomen, the metabolically most dangerous fat depot. Sleep-deprived individuals also make measurably worse food choices, gravitating toward higher-calorie, higher-carbohydrate options.

The factors driving sleep deprivation are themselves structural: artificial light disrupting circadian rhythms, smartphone use before bed, shift work schedules, high-stress work environments, and economic insecurity that creates cortisol elevation that impairs sleep quality even when duration is adequate.

See the MAHA approach to sleep optimization →

Root Cause #7: Chronic Stress and Cortisol

The relationship between psychological stress and metabolic health is direct and biochemically well-understood.

Cortisol — the primary stress hormone — serves the acute function of mobilizing energy for immediate physical threat response. It raises blood glucose, shifts metabolism toward fat storage (particularly visceral fat), suppresses immune function, increases appetite, and elevates cardiovascular workload.

These are adaptive responses to a tiger attack. They're maladaptive when triggered continuously by financial stress, relationship conflict, social media exposure, work pressure, and news consumption. Chronic cortisol elevation drives weight gain independent of caloric intake, impairs insulin sensitivity, suppresses testosterone and estrogen, and degrades sleep quality.

The American lifestyle — high stress, low community support, long work hours, economic precarity for many — generates chronic cortisol elevation at a population level. This is not a willpower problem. It's a social conditions problem.

📖 Related: For the policy wins enabling MAHA's mission, read Why Physical Fitness Should Be a Federal Priority Again.

What This Means for Solutions

If the root causes are structural — food industry economics, agricultural policy, built environments, marketing regulations, work culture — then purely individual-level solutions have inherent limits. No amount of willpower fully overcomes a food environment engineered to trigger overconsumption.

That said, individual action is not irrelevant. The structural critique is not a counsel of helplessness. People who understand the root causes can navigate around them more effectively:

• Eliminate seed oils by cooking at home with butter, tallow, lard, or olive oil — the cheapest available defense against the most pervasive dietary threat
• Walk more regardless of gym access — even 30 minutes of walking daily produces significant metabolic benefit
• Sleep-first lifestyle design — phone off an hour before bed, dark room, consistent schedule
• Budget-friendly real food — eggs, sardines, liver, ground beef, frozen vegetables, dried legumes are all affordable and nutritionally dense

Policy changes matter too. MAHA advocates for food policy reform, subsidy reallocation, and marketing restrictions — changes that would improve the food environment for everyone, not just those with health literacy and grocery budgets to navigate around it.

Explore the full MAHA history of American food to understand how we got here →

FAQ

Why are Americans so much less healthy than people in other wealthy countries? The U.S. has a uniquely adverse food environment: the highest per-capita ultra-processed food consumption among wealthy nations, the largest seed oil footprint, a built environment hostile to walking, limited social safety nets that increase chronic stress, and a healthcare system built almost entirely around treating disease rather than preventing it.

Is obesity just about eating too much and exercising too little? That's an oversimplification. Ultra-processed food is engineered to override normal satiety signals. Seed oils and refined carbohydrates alter hormonal regulation of hunger and fat storage. Sleep deprivation increases caloric intake. Chronic stress drives fat storage independent of caloric intake. The "calories in, calories out" model captures the physics but misses the biology.

Do food subsidies really affect what Americans eat? Yes, significantly. When policy makes the ingredients for ultra-processed food artificially cheap and provides no comparable support for fruits, vegetables, or grass-fed animal products, it creates price signals that shape purchasing decisions at scale — especially for lower-income households.

Can an individual make a difference given these structural problems? Yes. Individuals can eliminate seed oils from their home, walk more, prioritize sleep, and eat more real food regardless of policy environment. These actions also aggregate into cultural change. The MAHA movement is partly a bottom-up cultural shift that creates pressure for top-down policy reform.

What's the single most impactful dietary change for metabolic health? Eliminating industrial seed oils and ultra-processed food simultaneously addresses the two most significant dietary drivers of metabolic disease. If that's too big a step, starting with eliminating seed oils at home — cooking exclusively with butter, tallow, lard, or olive oil — is highly impactful and relatively simple.