Keto Collapse: The Problem with Trendy High Fat Diets, By Mrs Vera West

The article from Mercola.com (dated March 25, 2026) argues that high-fat diets, particularly those heavy in the style of keto or carnivore, can impair metabolic health over time, even if they produce short-term weight loss. It cites studies suggesting reduced insulin sensitivity, altered glucose handling, mitochondrial dysfunction, increased inflammation, and potential long-term risks for heart disease, diabetes, and other issues. This fits a recurring pattern in nutrition debates where one extreme (low-fat, high-carb) was demonised for decades, and now the pendulum has swung hard toward high-fat/low-carb being promoted as a cure-all.

There is a kind of mania in the diet world. Extremes sell books, supplements, subscriptions, programs, and clicks. Influencers, doctors, podcasters, and companies push "the one true diet" with religious fervour — whether it's strict keto, vegan, carnivore, or whatever comes next. Profits and tribal identity play a huge role. Social media amplifies the loudest voices, and nuance gets buried.

Getting Back to Basics: What Did Humans Actually Eat Historically?

Human ancestors weren't following any modern named diet. Paleolithic, hunter-gatherer, and traditional societies ate varied, opportunistic, whole-food diets that shifted with seasons, geography, and availability. Key patterns from anthropology, archaeology, and studies of remaining hunter-gatherer groups (Hadza, !Kung, Inuit, Maasai, etc.):

Not uniformly high-fat or low-carb:

oTropical/subtropical groups (many African, South American, Australian Aboriginal) often ate more plant foods: tubers, fruits, nuts, seeds, leaves, honey — higher in carbohydrates (including fibre and resistant starch). Animal foods supplemented when available.

oArctic groups (Inuit, some Siberian peoples) ate very high-fat from marine mammals and fish because plants were scarce — yet they had adaptations (genetic and metabolic) and often consumed organs, raw/fresh foods, and fermented items that modern keto dieters rarely replicate.

oTemperate groups mixed both: meat, fish, eggs, dairy (where herding developed), roots, berries, nuts.

Emphasis on whole, minimally processed foods: No seed oils, no ultra-processed foods, no refined sugars/flours in large amounts. Food was nutrient-dense, organs, bone broth, wild plants, seasonal variety.

Intermittent feasting/fasting and high activity: Periods of plenty followed by scarcity. Daily energy expenditure was much higher than modern sedentary life. No constant snacking.

Carbohydrate sources were different: Mostly from whole plants, tubers, fruits — not liquid sugar, bread, or pasta. Many traditional carbs came with fibre, polyphenols, and were eaten after physical work.

Fats were natural: Animal fats (including from wild game, which is leaner than grain-fed beef), fish, nuts, seeds, avocados (in some regions), coconut in tropics. Rarely the massive amounts of concentrated fats poured on everything in modern "high-fat" recipes (butter coffee, fat bombs, etc.).

Studies of traditional diets (e.g., Blue Zones research, though debated; or Kitava study; or analyses of pre-agricultural humans) show low rates of modern chronic diseases when people ate real food in context of their environment and lifestyle. Dental health, atherosclerosis evidence in mummies, and isotopic analysis of bones tell a story of diversity, not one-size-fits-all.

The Problems with Extreme High-Fat Diets (Like Strict Keto Long-Term)

The Mercola piece echoes concerns raised by some researchers and clinicians:

Insulin sensitivity and glucose metabolism: Some studies show that very low-carb/high-fat can lead to "physiological insulin resistance" in muscles (a normal adaptation to spare glucose for the brain), but in others it may impair overall metabolic flexibility — the ability to switch between burning carbs and fats efficiently. If you reintroduce carbs later, tolerance can be worse temporarily.

Mitochondrial function and inflammation: High saturated fat intake (especially in excess, without balancing omega-3s or nutrients) can increase oxidative stress or endotoxin load in some people, particularly if gut health or fiber intake suffers.

Nutrient gaps and sustainability: Strict keto often displaces nutrient-rich plants (vegetables, fruits, legumes in moderation). Long-term adherents sometimes report issues with thyroid, hormones, sleep, or "keto flu" that doesn't resolve. Electrolytes, bile flow, and gallbladder health matter.

Individual variation: Genetics (e.g., APOE4 variants may handle saturated fat differently), gut microbiome, activity level, stress, and existing metabolic health all play roles. What works short-term for weight loss or epilepsy (keto's proven medical use) doesn't always translate to optimal longevity or performance for everyone.

Over-reliance on processed "keto" products: Many commercial versions are loaded with artificial sweeteners, seed oils, isolates — defeating the "real food" goal.

That said, high-fat/low-carb approaches do help many people: rapid fat loss, better blood sugar control for type 2 diabetes/reversal in some cases, reduced hunger via ketosis/appetite suppression, improved mental clarity for certain individuals. Short-to-medium term use (months to a couple years) under guidance can be therapeutic, especially for insulin-resistant or obese people coming from a standard Western diet.

Dangers of the Opposite Extreme (Low-Fat Dogma)

We can't ignore the history. The low-fat, high-grain recommendations from the 1970s–2000s coincided with rising obesity, diabetes, and metabolic syndrome. Demonising all fat (including natural sources like eggs, butter, meat) while promoting refined carbs and industrial seed oils was a public health failure for many. "Fat makes you fat" ignored basic biochemistry and satiety signals.

A Balanced, "Back to Basics" Approach

Instead of swinging between extremes, consider these evidence-based principles that align with how humans historically thrived:

1.Prioritise real, whole foods: Meat, fish, eggs, organs (if tolerated), vegetables, some fruits, nuts/seeds, limited whole grains or legumes depending on tolerance. Minimise ultra-processed junk, seed oils (canola, soybean, etc.), added sugars, and refined carbs.

2.Personalise carb and fat intake:

oActive people or those with good metabolic health often do well with moderate carbs from whole sources (roots, fruits, some grains).

oInsulin-resistant or sedentary folks may benefit from lower-carb periods.

oCyclical or targeted approaches (e.g., higher carb on workout days) can maintain metabolic flexibility.

3.Focus on quality and context:

oPasture-raised/wild animal foods when possible.

oSeasonal, local, diverse plants.

oCooking methods: gentle (steaming, slow-cooking) over constant deep-frying or charring.

oPair with movement, sleep, stress management, sunlight.

4.Monitor and experiment: Track how you feel, energy, sleep, blood markers (fasting glucose, HbA1c, lipids, inflammation like hs-CRP, thyroid). Work with a knowledgeable practitioner if you have health issues. Avoid ideological rigidity.

5.Avoid mania and profit-driven hype: Question anyone selling "the diet" as permanent salvation. Traditional eating was pragmatic, not dogmatic.

Humans evolved as adaptable omnivores. Our ancestors ate what was available without counting macros or following gurus. In modern environments flooded with hyper-palatable processed food, the "basics" are: eat mostly single-ingredient foods, move your body, don't overeat, and find what sustains your health long-term without extremes that require constant willpower or supplements.

The Mercola article highlights valid cautions against treating high-fat as universally superior or risk-free. But the solution isn't returning to low-fat dogma either. It's rejecting both manias for thoughtful, individualised, ancestral-inspired eating rooted in real food and lifestyle.

https://articles.mercola.com/sites/articles/archive/2026/03/25/high-fat-diet-metabolic-health.aspx