Burnout: The Fall of the Keto Era

The high-fat, low-carb craze that promised easy weight loss left us with bad breath, high cholesterol, and the bitter aftertaste of metabolic overreach.

If you’ve ever caught a whiff of keto breath — that sharp, metallic odor born from the body burning fat instead of carbs — you’ve smelled desperation disguised as health. Once hailed as the ultimate fat-burning hack, the ketogenic diet (keto) promised mental clarity, boundless energy, and total metabolic control.

From Silicon Valley “biohackers” sipping buttered coffee to lifestyle influencers treating bacon as health food, keto became less a diet than a declaration of identity. Now that identity is fading, and that’s good news for both science and sanity.

What Keto Was All About

The ketogenic diet didn’t begin as a wellness trend. It was originally a medical therapy for epilepsy, developed in the 1920s to mimic the effects of fasting and reduce seizures in children with drug-resistant forms of the condition — a treatment born from necessity, not lifestyle optimization [1, 2].

Decades later, it was rebranded as a modern solution for weight loss, gaining traction in the 1990s and beyond [3]. At its core, the ketogenic diet nearly eliminates carbohydrates (often less than 50 grams a day, compared to the 250 most people need), forcing the body into ketosis — a state where fat breaks down into ketones that replace glucose as the main fuel source.

Followers cut out grains, fruits, legumes, and starchy vegetables, replacing them with meat, eggs, and high-fat dairy. For many, keto wasn’t just a diet but a declaration — a promise of mastery over hunger, weight, even aging, wrapped in the allure of an all-you-can-eat buffet of sizzling bacon, melted cheese, and a pat of butter to finish it off.

But the indulgence came with a price. Alongside the notorious keto breath, many experienced a vague cluster of side effects known as the keto flu. As the body shifts from burning glucose to fat, this transition can trigger fatigue, headaches, brain fog, and irritability — a reminder that the cost of keto isn’t just psychological but physiological.

And for those chasing fast results, reality hit hard. Many consumers expected rapid weight loss, only to see progress stall and pounds return once the diet was abandoned [3]. What began as a movement built on “metabolic efficiency” ended as so many fads do, with frustration and the realization that biology doesn’t bend to marketing.

Why Ketones Aren’t the Ideal Fuel

The body can adapt to ketones, but it isn’t meant to rely on them long term. Glucose remains its most efficient and versatile energy source, especially for high-demand organs and active muscles.

• The brain runs primarily on glucose to power nerve signaling and neurotransmitter synthesis. Even in ketosis, it still needs a baseline glucose supply.
• Red blood cells lack mitochondria and cannot use ketones at all — they rely entirely on glucose.
• Skeletal muscle, particularly during exercise, depends on glucose and glycogen because carbohydrate oxidation produces energy far faster than fat metabolism.
• The heart often uses fatty acids at rest but shifts toward glucose during exertion for better efficiency.

Ketones are an emergency backup — a survival mechanism for famine or fasting — not a foundation for health. When that backup system becomes the body’s default, it turns from adaptation into strain.

Science Pushed Back

Keto’s unraveling didn’t start with influencers; it started with data. A Wired investigation detailed the uproar around a 2025 study on “Lean Mass Hyper-Responders,” keto followers whose cholesterol spiked despite otherwise healthy profiles [4].

Published in JACC: Advances, the KETO-CTA trial followed 100 keto adherents whose LDL cholesterol skyrocketed on the diet [5]. The authors claimed that despite soaring LDL and ApoB levels, participants showed little arterial plaque buildup over a year.

The backlash was swift. Cardiologists accused the team of downplaying cardiovascular risk and using flawed methods. Others pointed out that the data actually showed a sharp rise in non-calcified plaque — the unstable kind most likely to rupture [5].

Amid mounting scrutiny, the authors issued corrections that confirmed critics’ concerns [4]. They admitted key data had been left out and conceded their findings supported, not challenged, the established link between high LDL and heart disease.

A study with such flaws should never have been published. Passing peer review gave the KETO-CTA paper false legitimacy, turning weak data into headlines and fueling misinformation. Even Bruce Klatt, an editor at the American Journal of Clinical Nutrition, admitted, “I would like to believe that we would have rejected this outright without even sending it out for peer review” [4]. Belief, however, has no place in science — only rigor does.

The episode exposed a deeper question at the heart of the keto movement: if a diet built on fats accelerates plaque buildup, what exactly are we optimizing — health or habit?

The Great Keto Cool-Down

As the science turned, so did public sentiment. According to FoodNavigator-USA, online mentions of “keto” dropped 18.5% in 2025, and keto-labeled restaurant items fell 12.3% [3].

Years of celebrating butter, bacon, and cheese as “superfoods” have taken their toll. Diets heavy in animal fat may deliver short-term weight loss, but they also raise LDL cholesterol, strain the gut microbiome, and increase inflammation — the very conditions keto promised to solve.

After years of fearing fruit and demonizing grains, people are simply exhausted. The promise of effortless control has given way to fatigue and disillusionment.

At the same time, GLP-1 medications like semaglutide are reshaping the weight-loss landscape. Instead of counting macros or cutting carbs, many are turning to medical tools that don’t demand a life of restriction [3].

Food companies are adjusting too: “keto-friendly” labels are fading, replaced by high-protein, low-sugar, and gut-friendly branding. It’s not necessarily progress, just another rebrand of the same fixation on shortcuts.

In the end, the keto era didn’t just burn fat; it burned out its followers.

Why Keto’s Decline Is Worth Celebrating

Keto’s fall marks more than the end of a fad; it’s the beginning of a reset. For years, we called saturated fat and cholesterol “fuel,” ignoring the mounting evidence that diets rich in meat, dairy, and eggs undermine heart health, longevity, and planetary balance.

Now, the shift away from animal-heavy eating patterns offers something genuinely hopeful: a return to foods that nourish rather than deplete. Whole plant foods — fruits, vegetables, grains, legumes, nuts, and seeds — supply the fiber, antioxidants, and complex carbohydrates that sustain metabolism and protect against disease.

The real story isn’t that keto failed, but that it should have never been marketed as a blueprint for thriving. A diet originally designed to suppress seizures in sick children was never meant to be a lifestyle. The fact that it became one says less about nutrition and more about our culture’s fixation on excess and instant reward.

Its decline reminds us that progress in nutrition doesn’t come from hacking biology; it comes from finally feeding it what it was designed to thrive on.

The Takeaway

Keto was the ultimate experiment in metabolic control, but nature always wins. Its decline shows that health trends are finally catching up with physiology. Real wellness isn’t about eating without limits; it’s about choosing the right ones — the kind that prioritize nourishment over novelty, and whole foods over gimmicks.

As keto fades from the spotlight, it leaves room for a new era of eating grounded in evidence, intention, and compassion — one that renews both our health and our connection to the food that sustains us.

References

[1] Wheless, James W. “History of the Ketogenic Diet.” Epilepsia 49, suppl. 8 (2008): 3–5. https://doi.org/10.1111/j.1528-1167.2008.01821.x.
[2] Ułamek-Kozioł, Marzena, Sławomir Januszewski, Stanisław J. Czuczwar, and Ryszard Pluta. “Ketogenic Diet and Epilepsy.” Nutrients 11, no. 10 (October 18, 2019): 2510. https://pmc.ncbi.nlm.nih.gov/articles/PMC6836058/.
[3] Eastlake, Donna. “Keto Diet Decline: What It Means for the Food Industry.” FoodNavigator-USA, September 11, 2025. https://www.foodnavigator-usa.com/Article/2025/09/11/keto-diet-decline-what-it-means-for-the-food-industry/.
[4] Rodrigues, Ashwin. “How One Keto Trial Set Off a New War in the Nutrition World.” Wired, June 4, 2025. https://www.wired.com/story/how-one-trial-set-off-a-new-war-in-the-nutrition-world-keto-cholesterol-fat/.
[5] Soto-Mota, Adrian, Nicholas G. Norwitz, Venkat S. Manubolu, et al. “Plaque Begets Plaque, ApoB Does Not: Longitudinal Data From the KETO-CTA Trial.” JACC: Advances, April 7, 2025. https://doi.org/10.1016/j.jacadv.2025.101686.