A Brief History of Diets: From Cabbage Soup to Keto, and What the Science Says

A calm, slightly amused tour through humanity's complicated relationship with food, and the eating patterns the evidence actually supports.

A Hundred Years of Diet Absurdity

In the 1920s, doctors prescribed cigarettes for weight loss. In the 1930s, half a grapefruit before every meal was supposed to "burn fat." In the 1990s, an entire generation ate fat-free cookies, gained weight, and blamed themselves. Today, you can choose between keto, paleo, carnivore, intermittent fasting, plant-based, and a dozen permutations of each.

Every decade gets the diet it deserves.

The interesting thing is not that humans keep trying new diets. It is that almost every one of them quietly works in the same way, fails in the same way, and reveals more about the era's anxieties than about human biology. This is a history of how we got here, what the research actually supports, and how to think about your own plate without taking the bait every January.

Quick Summary

There is no single best diet for everyone, and that is one of the better-supported findings in modern nutrition science. Decades of randomized trials, meta-analyses, and personalised-nutrition research point in the same direction: dietary pattern quality is more predictive of long-term health than dietary identity.^1,2,3 The Mediterranean diet has the strongest long-term randomized-trial evidence for cardiovascular protection (about 30 percent fewer major cardiovascular events in PREDIMED) and is also associated with reduced risk of cognitive decline.^1,4 A landmark 2015 study found that individuals' blood sugar responses to identical foods vary dramatically, partly explained by gut microbiome composition.² A 2018 trial found no significant 12-month weight-loss difference between healthy low-fat and healthy low-carb eaters when both groups focused on whole foods.³ Most fad diets achieve early weight loss the same way: by quietly creating a calorie deficit. The interesting question is not which label to pick, but which long-term pattern you can actually live with.

Key Terms

Dietary pattern: The overall composition of how someone eats across many meals, rather than a single rule or restriction. Patterns predict long-term outcomes better than any single food.¹

TMAO (trimethylamine N-oxide): A metabolite produced when certain gut bacteria break down compounds in red meat (especially carnitine) and eggs. Higher levels are associated with cardiovascular risk in observational and mechanistic studies.^5,6

Gut microbiome: The community of trillions of microbes living in the digestive tract. It helps digest fiber, produces short-chain fatty acids like butyrate, and modulates aspects of immunity, metabolism, and even how you respond to food.^7,8

PREDIMED: A large Spanish randomized controlled trial (n=7,447) that found about a 30 percent reduction in major cardiovascular events in people randomized to a Mediterranean dietary pattern compared with a reduced-fat control.¹

Postprandial glycemic response: The blood sugar rise after a meal. The same food can produce very different responses in different people, partly because of differences in the gut microbiome.²

A Brief, Slightly Embarrassing History

The first widely circulated weight-loss pamphlet in the English-speaking world was published in 1863 by an English undertaker named William Banting. Letter on Corpulence described a low-carbohydrate, higher-protein approach that predates Atkins by 110 years.⁹ It was personal, anecdotal, and surprisingly enduring.

By 1928, the American Tobacco Company had figured out that diet anxiety sells. The "Reach for a Lucky instead of a sweet" campaign marketed Lucky Strike cigarettes as appetite suppressants and is credited with a substantial share gain for the brand inside a year.¹⁰ Doctors were sometimes pictured in the ads. The 20th century is, in part, the story of medicine being repeatedly enlisted to sell things.

The tapeworm diet, much beloved by lurid history articles, is more legend than evidence. Most surviving "tapeworm pill" advertisements appear to be fabricated or unverified, and the practice was almost certainly far rarer than the internet would have you believe.¹¹ It is a useful reminder that diet history needs a fact-checker.

The 1930s gave us the grapefruit diet, which credited the fruit with mystical fat-burning enzymes. Any weight loss came not from grapefruit but from the diet's underlying severe calorie restriction.¹² The 1970s produced Atkins, a high-fat, very-low-carbohydrate plan that triggered decades of nutritional argument and one of the bestselling diet books in history.¹³

Then the 1980s and 1990s rotated the entire axis. Public health agencies and food manufacturers pushed low fat. SnackWell's launched, sold over a billion packages, and helped catalyze what cultural historians would later call the SnackWell Effect: people ate more of the "healthy" low-fat version than they would have of the original.¹⁴ Lots of fat-free, lots of refined carbohydrate, lots of weight gained.

The 2000s and 2010s brought paleo, then keto, then intermittent fasting, each repositioning itself as the antidote to the previous decade's mistake. The US weight-loss industry, the entity that makes money on all of this, was estimated at around 90 billion dollars in 2023.¹⁵

A timeline of diet history is, at one level, a timeline of commerce. At another level, it is a timeline of how slowly we incorporate evidence.

The Hidden Pattern Across Every Diet

Strip every popular diet down to its mechanism and most of them are doing the same thing: creating a calorie deficit, usually by removing a category of food. Banting removed carbohydrates. The grapefruit diet removed almost everything. Atkins removed carbohydrates again. SnackWell-era diets removed fat. Keto removes carbohydrates. Paleo removes grains, legumes, and dairy. Intermittent fasting removes a chunk of the day. Carnivore removes plants.

This is not a moral failing of any single diet. It is structural. If you take a normal mixed eater and you eliminate or sharply restrict a major food category, you almost always lower their total intake, at least at first.

The second pattern is what happens afterward. Without a sustainable behavioral structure, most people drift back. This is why long-term outcomes in dietary trials tend to converge much more than short-term ones. A 2018 Stanford trial (DIETFITS, n=609) randomized adults to either a healthy low-fat or a healthy low-carbohydrate diet for 12 months. Both groups lost weight, both improved blood pressure and glucose, and the difference between them was not statistically significant. Genotype and insulin secretion did not reliably predict which person would do better on which diet.³ In the words of the study's principal investigator, food quality, meaning minimally processed, whole foods, mattered more than which macro the label emphasized.

The macronutrient wars have always been a slightly silly argument.

What the Evidence Actually Supports

If you ask the research what eating patterns produce the best long-term outcomes, the same answer keeps showing up.

The Mediterranean diet has the strongest randomized-trial backing of any popular dietary pattern. The PREDIMED trial enrolled 7,447 adults at high cardiovascular risk and randomized them to a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a reduced-fat control diet, with a median follow-up of about 4.8 years. The Mediterranean arms had about a 30 percent reduction in major cardiovascular events compared to control.¹ The trial was reanalyzed in 2018 after questions about randomization at some sites; the corrected analysis confirmed the original findings.¹ A 2022 secondary-prevention trial, CORDIOPREV, followed coronary patients for seven years and again found the Mediterranean arm outperformed a low-fat arm on major cardiovascular events.¹⁶

The cognitive side of the story is more observational, with a smaller pool of RCT evidence. A 2025 meta-analysis associated higher Mediterranean diet adherence with roughly an 11 to 30 percent lower risk of cognitive impairment, dementia, and Alzheimer's disease across studies.⁴ An earlier RCT in older adults showed improved cognitive function with the Mediterranean diet supplemented with olive oil or nuts compared to a low-fat control.¹⁷

The gut microbiome story sits inside the same dietary pattern. A 2024 systematic review found that Mediterranean-style eating is associated with greater microbial diversity and a higher proportion of short-chain fatty acid producers in the gut.⁷ Fiber-rich, plant-forward patterns generally show this signal.^7,8

This is not a claim that the Mediterranean diet is the only good way to eat. It is a claim that, if you wanted to recommend a single pattern with the strongest stack of long-term outcomes behind it, this is the one.

Why There Is No Single Best Diet

In 2015, a research group at the Weizmann Institute published a landmark paper in Cell. They tracked 800 adults across a week of detailed food and glucose monitoring, capturing the blood sugar response to almost 47,000 meals. The finding that made the paper famous was simple and uncomfortable for the diet industry: glycemic responses to identical foods varied dramatically between individuals.² Bread spiked one person's glucose and barely moved another's. Differences in the gut microbiome were one of the strongest predictors of those individual responses.²

When the researchers built a machine-learning algorithm that integrated each person's microbiome, dietary habits, and other variables, the personalised predictions outperformed standard glycemic-index rankings, and personalised meal plans reduced postprandial glucose more than generic advice.²

This is the single best argument against universal dietary prescriptions. Two reasonable people can eat the same well-designed meal and produce meaningfully different metabolic responses to it. The takeaway is not that nutrition science has nothing to say. It is that the most useful question is not "which named diet is best" but "which sustainable pattern fits your body, your life, and your microbiome."

Personalised nutrition as a clinical product is still emerging. The research finding is robust. The consumer infrastructure is not yet at the point where most people can usefully act on it through testing. The closest practical version, for now, is paying attention to how you actually respond to foods over weeks and seasons, rather than what an influencer says you should respond to.

The Gut Microbiome: The Variable Older Diets Ignored

One reason older diet thinking aged badly is that it was built before we understood the gut microbiome. Almost every major dietary pattern looks different through that lens.

High-fiber, plant-rich patterns, including Mediterranean-style and largely plant-based diets, consistently feed a more diverse microbial community and increase production of beneficial short-chain fatty acids, especially butyrate.^7,8 Butyrate supports the gut lining, helps regulate inflammation, and has been linked to metabolic and immune outcomes.⁸

Ketogenic diets, by sharply restricting fermentable carbohydrate, generally reduce Bifidobacterium and butyrate-producing bacteria in human studies, according to a 2022 systematic review of eight studies.¹⁸ Whether those shifts translate to meaningful long-term clinical harm is not yet established, but it is a real signal worth knowing if you eat keto for years.

Paleo, often marketed as gut-friendly, has had an awkward run of evidence on this point. A cross-sectional study from Edith Cowan University compared long-term strict paleo followers to control adults eating a more standard balanced diet that included grains. The paleo group had significantly higher serum TMAO, a gut-derived metabolite associated with cardiovascular risk, and lower levels of butyrate-producing Roseburia and Bifidobacteria.¹⁹ This is a cross-sectional finding, not a controlled trial, so causation is not established, but it is the opposite of what the diet's marketing usually claims.

The TMAO connection sits across several dietary patterns. Chronic red meat consumption raises TMAO roughly threefold compared to white meat or non-meat diets, via the gut microbiome's metabolism of carnitine.⁵ Observational data suggest that TMAO and related metabolites may mediate roughly 8 to 11 percent of the excess cardiovascular risk associated with higher red meat intake.⁶ Individual responses vary, and not everyone produces TMAO at the same rate. It is one mechanism among several, not a single villain.

The simple gut-level rule that holds up across this research is that eating patterns rich in plants and fiber tend to produce more microbial diversity and more short-chain fatty acids, and that this is associated with better long-term cardiometabolic health.^7,8

A Quick, Honest Verdict on Modern Diets

A short, fair pass through the most-asked-about modern approaches.

Mediterranean. Strongest long-term RCT evidence, especially for cardiovascular and cognitive outcomes, with supportive gut-microbiome data.^1,4,7,16 The current default recommendation if you want one.

Keto. Useful as a clinical tool for certain conditions and supported for short-to-medium term metabolic markers in many people. The gut-microbiome shifts (lower Bifidobacterium, lower butyrate producers) are a real, persistent signal in the human evidence.¹⁸ Long-term general-population trade-offs remain unsettled.

Paleo. A reasonable nudge to eat less ultraprocessed food. The historical premise (eat like your Paleolithic ancestors) is looser than its branding suggests, and the cross-sectional gut-and-TMAO data do not match the gut-friendly marketing.^5,19

Intermittent fasting. Promising. A 2024 umbrella review of 23 meta-analyses found high-quality evidence linking time-restricted eating to weight loss, fat-mass reduction, lower fasting insulin, and improved HbA1c in adults with overweight or obesity.²⁰ Long-term data beyond 12 months are limited, and it is not appropriate for everyone (including those with a history of disordered eating, certain medical conditions, or for some older adults without supervision).²⁰

Plant-based and vegetarian. Generally associated with better cardiometabolic and microbiome outcomes when whole foods are the base, with attention to a few specific nutrients (such as vitamin B12 and adequate protein quality). Worth its own article, briefly mentioned here for fairness.

Carnivore. Currently lacks human RCT support for the claimed long-term benefits, and the TMAO and fiber-deficit signals raise legitimate concern.⁵

The unifying answer, which is annoying because it is also the boring one, is that the differences inside each diet (how much processed food, how much fiber, how much real cooking) tend to dwarf the differences between them.

The Detox and Calorie Myths

Two leftover myths from a century of diet culture are still worth swatting away.

"You need to detox." The National Center for Complementary and Integrative Health, after reviewing the available evidence, concluded that there is no compelling research to support detox diets for either toxin elimination or weight management.²¹ Hepatologists at Johns Hopkins are unsentimental about the same point: the liver is the body's actual detoxification system, and liver "cleanses" are unregulated and not recommended.²² The kidneys handle most of the rest. Juice cleanses can deliver real, dramatic effects in the short term, but those effects are mostly the consequence of eating fewer calories for a few days, not any unique purification.

"A calorie is a calorie." True at the level of physics. Not the whole story at the level of physiology. Different foods produce different hormonal responses, different gut microbial effects, different fullness signals, and different downstream effects on energy expenditure.²³ Calorie balance still matters in the long run. The composition of those calories matters for how easily you stay in balance, how hungry you are along the way, and how the body uses what you give it.

The reasonable position is to take both seriously: roughly track quality and quantity, and stop pretending one of them is the only thing that counts.

Practical Takeaways

If the history of dieting has a final lesson, it is that lasting eating patterns beat clever labels. A few principles that the evidence supports:

• Pick a pattern you can live with for a decade, not a month. Long-term cardiovascular, cognitive, and gut-microbiome outcomes are measured in years, not weeks.^1,4
• Default to mostly whole, mostly plant-rich, mostly home-cooked. Mediterranean-style eating is the best-evidenced template, but the principles travel across other patterns too.^1,4,7
• Prioritize fiber and food diversity. A varied plant intake feeds a varied microbiome, which is one of the more durable associations in modern nutrition.^7,8
• Be skeptical of anything described as a fat-burner, metabolism-booster, or reset. Most short-term diet effects are reproducible calorie restriction, not unique magic.
• Watch how you respond. Individual variation is real. If a pattern produces good energy, steady weight, decent sleep, and reasonable lab numbers over months, that is more useful information than a generic ranking.

Restraint and consistency are not exciting. They are also what most of the long-term evidence rewards.

The Bigger Picture

A century of diet history is mostly a story of overconfident answers to a quietly complicated question. There is no single right diet, but there are clearly better and worse patterns, and the better ones share a recognizable shape: real food, lots of plants and fiber, a structure you can actually keep, and a working relationship with your gut microbiome.

That last piece is the part older diet thinking simply could not see. It is also where WonderBiotics' work begins. A diverse, well-fed microbiome is one of several inputs that support metabolic and digestive health, alongside the eating pattern, sleep, movement, and stress habits that do the heavy lifting. Probiotics belong in the conversation as adjuncts, not as a workaround for the work of feeding yourself well.

If you want a single sentence to take from a hundred years of dieting: it is not the name on the diet that determines your health, it is the pattern underneath the name, and how long you can keep it up.

Related Reading

• For the deep-dive on the most-evidenced diet, see The Mediterranean Diet: What It Actually Is and Why the Science Loves It.
• Curious about the keto gut-microbiome story? Read The Keto Diet: Science, Benefits, Risks, and Gut Health.
• For an honest look at the ancestral premise, try The Paleo Diet: What Our Ancestors Really Ate and What the Science Says.
• Wondering about fasting? See Intermittent Fasting: What the Science Actually Says.
• Going deeper on the calories question? Read Are All Calories the Same?
• If you'd like to see our gut-targeted weight-support approach, visit Probiotics for Weight Management.

References

1. Estruch R, et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet (PREDIMED). NEJM / ACC summary. 2013 / 2018 reanalysis. link
2. Zeevi D, Korem T, Segal E, Elinav E, et al. Personalized Nutrition by Prediction of Glycemic Responses. Cell. 2015. link
3. Gardner CD, et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss (DIETFITS). JAMA. 2018. link
4. Li L, et al. Role of the Mediterranean Diet in Reducing Risk of Cognitive Disorders: Meta-Analysis. Frontiers in Aging Neuroscience. 2025. link
5. Cleveland Clinic / Hazen SL, et al. Studies Reveal Role of Red Meat in Gut Bacteria, Heart Disease. Cleveland Clinic Newsroom. 2018. link
6. American Heart Association. Chemicals Produced in the Gut After Eating Red Meat May Contribute to Heart Disease Risk. 2022. link
7. Khavandegar A, et al. Adherence to the Mediterranean Diet Can Beneficially Affect the Gut Microbiota Composition: A Systematic Review. BMC Medical Genomics. 2024. link
8. Cronin P, et al. Dietary Fiber Intake and Gut Microbiota in Human Health. PMC. 2022. link
9. Banting W. Letter on Corpulence, Addressed to the Public. 1863. link
10. Djublonskopf.com. Reach For A Lucky: The Lucky Strike Cigarette Diet (1928). 2015. link
11. Hektoen International. The Tapeworm Diet: Myth, Mostly. 2023. link
12. Encyclopedia.com. Grapefruit Diet. link
13. Wikipedia contributors. Atkins diet. Accessed 2026. link
14. Tasting Table. The 'Healthy' Low-Fat Cookie That Defined The '90s. link
15. Marketdata Enterprises. U.S. Weight Loss Industry Grows to $90 Billion. 2024. link
16. Delgado-Lista J, et al. Mediterranean Diet Bests Low Fat for Secondary Prevention (CORDIOPREV). 2022. link
17. Valls-Pedret C, et al. Mediterranean Diet and Age-Related Cognitive Decline: A Randomized Clinical Trial. JAMA Internal Medicine. 2015. link
18. Harris M, et al. The Ketogenic Diet: Its Impact on Human Gut Microbiota. Gastroenterology and Hepatology From Bed to Bench. 2022. link
19. Genoni A, et al. Long-Term Paleolithic Diet and Gut Microbiota / TMAO. European Journal of Nutrition. 2019. link
20. Cao Y, et al. Intermittent Fasting and Health Outcomes: An Umbrella Review. eClinicalMedicine. 2024. link
21. NCCIH. "Detoxes" and "Cleanses": What You Need to Know. 2023. link
22. Woreta T (Johns Hopkins). Detoxing Your Liver: Fact Versus Fiction. 2025. link
23. Harvard Health. There's No Sugar-Coating It: All Calories Are Not Created Equal. 2016. link

This article is for educational purposes only and isn't medical advice. It isn't intended to diagnose, treat, cure, or prevent any disease. If you have symptoms, a medical condition, are pregnant or breastfeeding, or take medications, talk with a licensed clinician before making health changes or starting supplements.