Why is Everyone Obsessed With Intermittent Fasting?
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Intermittent fasting is the most Googled diet-related term on the planet — except everyone who does it will tell you it's not a diet. It's a protocol. An eating window. A lifestyle. An optimization hack. Definitely, absolutely, under no circumstances a diet. You just don't eat for sixteen hours. Totally different.
In this episode, we trace IF from ancient religious fasting traditions through its secularization and commodification — from Martin Berkhan's Leangains forum to Michael Mosley's BBC documentary, Hugh Jackman's Wolverine physique, and Jack Dorsey describing his weekend-long fasts as "hallucinating" like that's a selling point. We walk through how a Nobel Prize in yeast biology became a justification for skipping breakfast, why Jason Fung's The Obesity Code scored 31% on scientific accuracy and still became the IF bible, and how the fasting app market turned one simple rule into a multimillion-dollar industry.
Then we get into what the science actually says. We break down the claimed mechanisms — metabolic switching, autophagy, insulin sensitivity — and look honestly at where the evidence lands. The mechanisms are real, but the confidence far outpaces the human data. The first direct measurement of autophagy in humans was published in 2025. Mouse metabolism runs seven times faster than ours. And the landmark Liu et al. trial in the New England Journal of Medicine found that time-restricted eating is no better than regular caloric restriction for weight loss. You're not metabolic switching. You're just eating less.
We also dig into what IF means for active people — no performance benefit across any exercise type, real risk of under-fueling and RED-S, and a protein distribution problem that no eight-hour window can solve. We cover what the AHA, ADA, NIA, and ISSN actually say about it, the robust research linking IF to eating disorder behaviors across all genders, and a landmark study showing that fasting was a stronger predictor of binge eating disorder than any other form of dietary restraint. Fasting is listed in the DSM-5 as a compensatory behavior. Just because you give it a different vocabulary doesn't mean your body experiences it differently.
Your body is smarter than any fasting app. Also, breakfast slaps.
Resources and studies cited in this episode are available at yourdiet.sucks.
APA REFERENCES
Bensalem, J., et al. (2025). Effects of intermittent time-restricted eating on autophagy markers in humans: A randomized controlled trial. The Journal of Physiology. https://doi.org/10.1113/JP287890
Bulik, C. M. (as quoted in Kaplan, S.). If female Silicon Valley execs came out with New York Times articles on biohacking, they would be pounced on as having eating disorders. Quartz/Yahoo News.
Cleveland Clinic. (n.d.). Autophagy: What it is, benefits & how to induce it. Cleveland Clinic Health Library. https://my.clevelandclinic.org/health/articles/24058-autophagy
Ganson, K. T., Cuccolo, K., Hallward, L., & Nagata, J. M. (2022). Intermittent fasting: Describing engagement and associations with eating disorder behaviors and psychopathology among Canadian adolescents and young adults. Eating Behaviors, 47, 101681. https://doi.org/10.1016/j.eatbeh.2022.101681
Hofmekler, O. (2001). The Warrior Diet: Switch on your biological powerhouse for high energy, explosive strength, and a leaner, harder body. Dragon Door Publications.
Hornbacher, M. (1998). Wasted: A Memoir of Anorexia and Bulimia. Harper Perennial.
Fung, J. (2016). The Obesity Code: Unlocking the Secrets of Weight Loss. Greystone Books.
International Food Information Council. (2018). 2018 Food and Health Survey. IFIC Foundation.
International Society of Sports Nutrition. (2017). ISSN position stand: Nutrient timing. Journal of the International Society of Sports Nutrition, 14, 33. https://doi.org/10.1186/s12970-017-0189-4
Liu, D., Huang, Y., Huang, C., Yang, S., Wei, X., Zhang, P., ... & Zhao, J. (2022). Calorie restriction with or without time-restricted eating in weight loss. New England Journal of Medicine, 386(16), 1495–1504. https://doi.org/10.1056/NEJMoa2114833
Mosley, M., & Spencer, M. (2013). The Fast Diet: Lose Weight, Stay Healthy, and Live Longer with the Simple Secret of Intermittent Fasting. Atria Books.
Neumark-Sztainer, D., Wall, M., Guo, J., Story, M., Haines, J., & Eisenberg, M. (2006). Obesity, disordered eating, and eating disorders in a longitudinal study of adolescents: How do dieters fare 5 years later? Journal of the American Dietetic Association, 106(4), 559–568. https://doi.org/10.1016/j.jada.2006.01.003
Ohsumi, Y. (2016). Nobel Prize in Physiology or Medicine for discoveries of mechanisms for autophagy. Nobel Prize Organization. https://www.nobelprize.org/prizes/medicine/2016/ohsumi/facts/
Red Pen Reviews. (n.d.). The Obesity Code by Jason Fung — review. Red Pen Reviews. https://redpenreviews.org/reviews/the-obesity-code/
Verity, K. S., et al. (2023). Effects of intermittent fasting on DHEA levels in pre- and post-menopausal women. UIC [note: verify journal name and full citation].
Ashtary-Larky, D., Bagheri, R., Tinsley, G. M., Asbaghi, O., Paoli, A., & Moro, T. (2021). Effects of intermittent fasting combined with resistance training on body composition: A systematic review and meta-analysis. Physiology & Behavior, 237, 113453. https://doi.org/10.1016/j.physbeh.2021.113453
American Heart Association. (2023). Statement on time-restricted eating and cardiovascular health. Journal of the American Heart Association, 12(4), e028885.
American Diabetes Association. (2024). Standards of care in diabetes — 2024. Diabetes Care, 47(Supplement 1).
National Institute on Aging. (n.d.). Calorie restriction and fasting diets: What do we know? NIA. https://www.nia.nih.gov/health/healthy-eating-nutrition-and-diet/calorie-restriction-and-fasting-diets-what-do-we-know
Episode Deep Dive
Episode Summary
Intermittent fasting is the most Googled diet-related term on the planet — except everyone who does it will tell you it's not a diet. It's a protocol. An eating window. A lifestyle. An optimization hack. In this episode, Zoë and Kylee trace IF from ancient religious fasting traditions through its secularization and commodification — from Martin Berkhan's Leangains forum to Michael Mosley's BBC documentary, Hugh Jackman's Wolverine physique, and Jack Dorsey describing his weekend-long fasts as "hallucinating" like that's a selling point.
They walk through the claimed mechanisms — metabolic switching, autophagy, insulin sensitivity — and look at where the evidence actually lands. They dig into what IF means for active people, what major institutions say about it, and the robust research linking IF to eating disorder behaviors across all genders.
The History: From Monks to Silicon Valley
Fasting traditions span nearly every major religion — Ramadan, Lent, Yom Kippur, Buddhist fasting practices — but these traditions were embedded in spiritual discipline, community, and shared meaning. The modern IF movement strips that context away and repackages it as a productivity hack.
The secular version emerges in the 1960s with medically monitored clinical research. In the mid-2000s, Swedish fitness consultant Martin Berkhan develops the Leangains protocol (the origin of 16:8), marketed specifically to gym culture with his tagline: "fuck breakfast." In 2012, journalist Michael Mosley's BBC documentary Eat, Fast and Live Longer brings IF to mainstream audiences. By 2013, Hugh Jackman publicly credits 16:8 for his Wolverine physique, taking IF from niche fitness forums to celebrity culture.
In 2016, three things converge: Yoshinori Ohsumi wins the Nobel Prize for autophagy mechanisms in yeast (not humans), Jason Fung publishes The Obesity Code (which later scores 31% on scientific accuracy from Red Pen Reviews), and tech entrepreneur Kevin Rose launches the Zero fasting tracker app. By 2018, IF becomes the most popular diet in America. Former Twitter CEO Jack Dorsey reveals he eats one meal a day and sometimes fasts entire weekends, describing the experience as "hallucinating" and saying "time really slowed down."
In 15 years, IF went from a niche bodybuilding forum to the most popular diet in America — powered by celebrity endorsements, Silicon Valley funding, and a Nobel Prize that the wellness industry claimed as a win.
The IF Protocols Explained
12:12 — 12 hours eating, 12 hours fasting (basically a normal eating schedule).
16:8 — 16-hour fast with an 8-hour eating window. This is the most popular and mainstream version, the one most apps track, and what most people mean when they say "intermittent fasting." Usually means skipping breakfast.
5:2 — Eat normally five days, severely restrict on two non-consecutive days. Popularized by Michael Mosley's BBC documentary.
OMAD (One Meal a Day) — Exactly what it sounds like. The Jack Dorsey special.
Alternate Day Fasting — Fast every other day. Pretty extreme.
Time-Restricted Eating (TRE) — The more scientific term researchers use. Limits eating to specific daily windows.
The Science: What's Real vs. What's Marketed
Metabolic switching: When you fast for 12–36 hours, your body depletes glycogen and your liver produces ketone bodies. The switch itself is real — basic physiology. The question is whether periodically triggering it via a 16:8 protocol produces clinically meaningful long-term benefits in humans. That's where the evidence gets thinner.
Autophagy: A real cellular process where cells break down and recycle damaged components. Ohsumi won the 2016 Nobel Prize for identifying these mechanisms — in yeast. The timelines commonly cited online ("autophagy starts at 16 hours, peaks at 48") come from animal studies. The first direct human measurement of autophagy wasn't published until Bensalem et al. in 2025 in The Journal of Physiology. The Cleveland Clinic's current position: not enough research to support autophagy as a wellness strategy.
Weight loss and insulin: Jason Fung's core argument is that fasting drops insulin, allowing fat mobilization. Insulin does drop during fasting, and lower insulin does facilitate fat burning. But the weight loss data consistently shows IF is not superior to caloric restriction. The landmark Liu et al. (2022) trial in the New England Journal of Medicine — 12 months, TRE versus caloric restriction — found no significant difference in weight loss or metabolic markers. You're just eating less.
What has NOT been demonstrated in humans: Extended lifespan, prevention of neurodegeneration, clinically meaningful autophagy, or performance enhancement.
Why Animal Studies Don't Translate Directly
Mouse metabolism runs approximately seven times faster than human metabolism. A 24-hour mouse fast is metabolically equivalent to roughly a week of human fasting — mice are being tested on something dramatically more extreme than what humans actually do.
Mice live about two years. A full lifespan study in a mouse would need decades to replicate in humans. We don't have that data. Controlled laboratory conditions — standardized diets, controlled temperatures, no social eating — don't reflect real human life. Diet is a fundamentally social, political, and financial experience.
Animal studies aren't irrelevant, but the expert formulation keeps coming back to: "Promising in animal models, warrants further investigation in humans." A plausible mechanism is not a proven clinical benefit.
What Major Institutions Actually Say
American Heart Association: No good evidence of heart health benefits.
American Diabetes Association: Limited evidence. Does not recommend any specific dietary pattern for blood sugar control via IF.
National Institute on Aging: Limited and inconclusive evidence. Does not recommend IF to the general public.
International Society of Sports Nutrition: Total energy and nutrient intake matters most. Timing is secondary.
At best, the major institutions say: maybe. That's not a yes.
IF and Athletic Performance
A 2019 ACSM review examining high-intensity, endurance, and resistance exercise found no benefit to athletic performance while fasting. None across exercise types.
Short exercise (under 1 hour): Largely unaffected. Fat oxidation increases at low-to-moderate intensity but doesn't translate to measurable performance gains.
Aerobic endurance: Ramadan studies show reduced VO2 max. TRE might slightly enhance VO2 max in some studies, but the data is sparse and heterogeneous.
Resistance training: Carbohydrate restriction from IF may reduce hypertrophy and training session capacity. Not helpful for muscle building.
Protein distribution: The body needs protein distributed throughout the day (every 3–4 hours) for optimal muscle protein synthesis. Cramming all protein into an 8-hour window is likely not ideal for muscle building or maintenance.
RED-S risk: IF can tip athletes into low energy availability without realizing it. Compressing eating into 8 hours may make it physically difficult to consume enough calories, especially for endurance athletes with high training loads. Signs are subtle — fatigue, poor recovery, hormonal disruption, increased injury.
Bottom line for active people: No performance benefit. Real risk of under-fueling. Best case: may not make you worse. Worst case: tips you into RED-S with downstream impacts on hormones, bones, immunity, and recovery.
IF and Women
Out of 71 studies cited in Harvard's database on intermittent fasting, only 13 include women at all. Zero controlled studies focus specifically on female populations. Confident claims about how IF translates to female physiology are based largely on research in male subjects.
A study by Verity et al. (2023) found that DHEA decreased in both pre- and post-menopausal women on intermittent fasting — concerning especially for women already experiencing estrogen decline. The Cleveland Clinic notes that fasting can affect estrogen and progesterone via GnRH sensitivity.
When women struggle with IF — energy tanks, menstrual cycles become disrupted — the response is typically "you're doing it wrong" rather than questioning whether the protocol was designed with their physiology in mind. The research was designed largely for and by men.
The Psychology: Why IF Sticks
IF feels different from other diets because it doesn't tell you what to eat — just when. It's one simple, binary rule. You're either eating or you're not. In a chaotic world, a diet that feels like a simple source of control is appealing.
The framing is always discipline and mastery, not deprivation: "I can control when I eat" rather than "I can't have bread." This is psychologically distinct from how diets have traditionally been marketed to women.
There's also the warrior monk archetype. Ori Hofmekler literally called his protocol The Warrior Diet. Geoffrey Woo of HVMN described the appeal as a "warrior or monk ethic." The message: you're tougher and more evolved than people who need three meals a day.
The euphoria is real. Fasting produces norepinephrine, BDNF, and ketone bodies. People genuinely feel more alert, focused, and euphoric — which makes it feel like it's working. Except the language tech CEOs use to describe this is identical to how people describe the early stages of an eating disorder. Marya Hornbacher described the addictive power of deprivation in her 1998 memoir Wasted. Science basically confirmed she was right.
IF and Eating Disorders
The research linking IF to disordered eating is significant, serious, and crosses all genders.
A landmark study by Kyle Ganson et al. at the University of Toronto looked at 2,762 Canadian adolescents and young adults aged 16–30. They found 47% of women, 38% of men, and 52% of transgender and gender nonconforming participants had tried IF in the past 12 months. IF was significantly associated with eating disorder psychopathology across all genders. In women, it was associated with every single measured ED behavior — overeating, binge eating, vomiting, laxative use, compulsive exercise, and fasting.
A 2008 longitudinal study of approximately 500 adolescent girls over five years found that fasting was a stronger predictor of binge eating disorder and subclinical bulimia nervosa than any other form of dietary restraint.
A 2021 study found that 31% of intermittent fasters scored at or above the clinical eating disorder cutoff on the EDE-Q. That's nearly one in three.
Fasting is listed in the DSM-5 as an inappropriate compensatory behavior in eating disorder diagnostic criteria. The behavior IF promotes is clinically recognized as a symptom of an eating disorder. Just because you give it a different vocabulary doesn't mean your body experiences it differently.
As eating disorders researcher Cynthia Bulik (University of North Carolina / Karolinska Institutet) noted: if female Silicon Valley execs described biohacking in the same terms, they would immediately be identified as having eating disorders. But because men are the proponents, it's viewed as less pathological. The same behavior gets different gendered framing.
The Gendered Double Standard
IF has been positioned as two completely different things depending on who it's marketed to. For men in tech, it's cognitive optimization and longevity hacking. For women, it's weight loss and hormone balancing. But it's the same skipped meal — just in different marketing.
Women have been socialized to talk about restricting food intake for generations. IF is essentially diet culture's way of bringing men into the same system with different branding: it's not a diet, it's a protocol. When a woman skips meals, we call it disordered. When a male CEO skips meals, we call it optimizing.
That framing makes it harder for anyone, regardless of gender, to recognize when restriction has become the problem. Eating disorders already go under-recognized and under-diagnosed in people socialized as men — and IF provides a socially acceptable framework for restriction that makes it even harder to spot.
Key Takeaways
IF is not pseudoscience — but it's not proven science either. It is preliminary science marketed as if it's settled science. The mechanisms are plausible. Some short-term markers improve. But it's not superior to eating less for weight loss. Autophagy hype far exceeds actual human evidence. The most impressive claims rest on animal models.
For athletes and active people: Consistently no performance benefit. Real risk of under-fueling. Eat before and after training. Distribute protein throughout the day. Total energy and nutrient intake matter more than timing.
Questions to ask yourself if you're doing IF: Am I eating enough calories and protein for my training load? Could I skip IF for a week without anxiety? Is this serving my performance and wellbeing, or someone else's idea of optimization?
The bottom line: Eating should support your life, not the other way around. Your body is smarter than any fasting app. Also, breakfast slaps.
Studies & Resources Cited
Liu, D. et al. (2022). Calorie restriction with or without time-restricted eating in weight loss. New England Journal of Medicine, 386(16), 1495–1504.
Bensalem, J. et al. (2025). Effects of intermittent time-restricted eating on autophagy markers in humans. The Journal of Physiology.
Ganson, K. T. et al. (2022). Intermittent fasting: Associations with eating disorder behaviors and psychopathology among Canadian adolescents and young adults. Eating Behaviors, 47, 101681.
Ohsumi, Y. (2016). Nobel Prize in Physiology or Medicine for mechanisms of autophagy.
Fung, J. (2016). The Obesity Code. Red Pen Reviews scientific accuracy score: 31%.
Hornbacher, M. (1998). Wasted: A Memoir of Anorexia and Bulimia. Harper Perennial.
Institutional positions: American Heart Association, American Diabetes Association, National Institute on Aging, International Society of Sports Nutrition, Cleveland Clinic.
Full APA reference list available at yourdiet.sucks.