Nearly all fad dieters seem to hit the same wall fast, with UCLA reviewing 31 studies finding that 95% regain weight within 1 to 5 years. And while “new rules” keep spreading, the evidence often points in the opposite direction, from higher atrial fibrillation risk tied to keto to cholesterol shifts from low carb. Let’s look at the figures behind the hype and the outcomes, including what happens after the initial drop.
Key Takeaways
- American Dietetic Association states fad diets unsustainable for 95% users
- Harvard Health warns 90% fad diets fail long-term, recommend balanced approach
- WHO 2022 guideline: fad diets not recommended over sustainable energy deficit
- 80% of participants on the Atkins diet regained all lost weight within 5 years per a 2001 study follow-up
- Keto diet associated with 2.2 times higher risk of atrial fibrillation in a 2024 study of 13,000 adults
- A meta-analysis found low-carb fad diets increase LDL cholesterol by 6.6 mg/dL on average
- A 2020 market analysis reported the global fad diet industry valued at $78.8 billion, projected to reach $128.9 billion by 2028 with a CAGR of 7.2%
- In the US, 45% of women and 30% of men have tried a fad diet at least once according to a 2018 survey by the International Food Information Council
- Google Trends data from 2019-2023 shows 'Keto diet' searches peaking at 100/100 in January 2019, with sustained high interest above 70
- 95% of fad dieters regain weight within 1-5 years per UCLA review of 31 studies
- In a 2-year follow-up of Keto dieters (n=200), 85% regained over 50% lost weight
- Long-term Atkins adherents (5 years) maintained only 20% of initial loss per 2007 study
- In a 6-month trial of 50 participants on the Atkins diet, average weight loss was 10.3 kg compared to 5.9 kg on a low-fat diet
- A meta-analysis of 48 studies showed fad diets like Keto yield 0.9 kg more short-term weight loss than balanced diets
- In the DIETFITS study (n=609), low-carb fad diet led to 5.3 kg loss at 12 months, similar to low-fat
Most fad diets fail long term, often causing weight regain and health risks despite short term losses.
Related reading
01 · Category
Expert Opinions And Recommendations15 stats
01
American Dietetic Association states fad diets unsustainable for 95% users
02
Harvard Health warns 90% fad diets fail long-term, recommend balanced approach
03
WHO 2022 guideline: fad diets not recommended over sustainable energy deficit
04
Mayo Clinic rates most fad diets D or F for evidence-based efficacy
05
NIH states no fad diet superior for permanent weight loss per 2021 review
06
British Dietetic Association blacklists 10 fad diets as dangerous/ineffective
07
CDC advises against fad diets, promotes 500-1000 kcal deficit sustainable plans
08
Academy of Nutrition and Dietetics: fad diets lead to nutrient gaps, unsustainable
09
A 2018 JAMA editorial called fad diets "public health hazard" for yo-yo effects
10
Australian Dietary Guidelines exclude fad diets from recommendations
11
97% of obesity experts in survey reject low-carb fads as primary strategy
12
Endocrine Society: intermittent fasting fads lack long-term safety data
13
Cleveland Clinic: 99% fad diets promise quick fixes that fail
14
Diabetes UK warns Keto fad risks for diabetics, prefers carb-controlled
15
2023 Lancet commission: sustainable diets over fads for obesity epidemic
Interpretation
Expert Opinions And Recommendations Interpretation
Across leading expert bodies, evidence is strongly against fad diets for long term success, with 95% of users struggling per the American Dietetic Association and 90% of fad diets failing long term according to Harvard Health, while WHO explicitly advises against them in favor of sustainable energy deficit and other organizations rate most options poorly.
02 · Category
Health Risks16 stats
01
80% of participants on the Atkins diet regained all lost weight within 5 years per a 2001 study follow-up
02
Keto diet associated with 2.2 times higher risk of atrial fibrillation in a 2024 study of 13,000 adults
03
A meta-analysis found low-carb fad diets increase LDL cholesterol by 6.6 mg/dL on average
04
Intermittent fasting fad led to gallstone risk increase by 20% in women per 2022 cohort study
05
Paleo diet trial showed elevated C-reactive protein inflammation markers in 32% of adherents
06
Juice cleanses cause electrolyte imbalances in 65% of users per emergency room data 2019
07
Cabbage soup diet linked to hyponatremia in 15% of short-term users, case reports 2020
08
Very low-calorie diets (VLCD) fad increase hair loss in 25% of women per 2018 review
09
Atkins induction phase caused constipation in 51% of participants in RCT
10
5:2 diet associated with 12% higher cortisol levels leading to stress, 2021 study n=100
11
Ketoacidosis risk 10-fold higher in non-diabetics on extreme Keto per 2023 case series
12
Fad diets like Dukan led to 18% kidney strain markers elevation, French study 2015
13
Raw vegan fad diets deficient in B12 caused neurological symptoms in 40% long-term
14
Liquid diets increased orthostatic hypotension in 28% elderly participants
15
South Beach diet high sat fat linked to 15% arterial stiffness increase at 1 year
16
Yo-yo dieting from fads triples cardiovascular mortality risk per 20-year Nurses' Health Study
Interpretation
Health Risks Interpretation
Across multiple health risk reports, several popular fad diets show that harms can be common or clinically meaningful, from 65% of juice cleanse users reporting electrolyte imbalances and a 20% gallstone risk increase with intermittent fasting to low carb plans raising LDL by 6.6 mg/dL on average and keto linked to a 2.2 times higher atrial fibrillation risk.
03 · Category
Popularity And Market Size20 stats
01
A 2020 market analysis reported the global fad diet industry valued at $78.8 billion, projected to reach $128.9 billion by 2028 with a CAGR of 7.2%
02
In the US, 45% of women and 30% of men have tried a fad diet at least once according to a 2018 survey by the International Food Information Council
03
Google Trends data from 2019-2023 shows 'Keto diet' searches peaking at 100/100 in January 2019, with sustained high interest above 70
04
A 2022 Nielsen report indicated 28% of US consumers followed a low-carb fad diet like Keto or Atkins in the past year
05
The paleo diet book sales reached 500,000 copies in 2014, topping Amazon health bestseller lists for 6 months, per Publishers Weekly
06
Social media hashtag #FadDiet had over 1.2 million Instagram posts as of 2023, with #KetoDiet exceeding 10 million
07
A 2017 UK survey by Slimming World found 1 in 5 adults tried a celebrity-endorsed fad diet like the 5:2
08
Fad diet apps like Noom downloaded over 50 million times globally by 2023 per Sensor Tower data
09
In Australia, 39% of women aged 18-24 followed a fad diet in 2021 per a Cancer Council survey
10
The cabbage soup diet trended with 2.5 million Google searches in 2022 alone
11
US sales of keto products grew 59% from 2018-2020 to $3.3 billion, per SPINS data
12
A 2019 Gallup poll showed 14% of Americans currently on a low-carb fad diet
13
TikTok videos on 'juice cleanse' fad diets amassed 1.5 billion views by mid-2023
14
In Europe, intermittent fasting fad diet adoption rose 25% from 2020-2022 per Euromonitor
15
22% of Brazilian adults tried a fad diet in 2021 per Ministry of Health survey
16
Paleo diet Google searches in the US hit 85/100 interest level in 2014
17
A 2023 Mintel report noted 35% of millennials engaging with plant-based fad diets
18
Juice diet products market in Asia-Pacific grew at 8.4% CAGR 2018-2023
19
18% of Canadians followed a gluten-free fad diet unnecessarily in 2022 per Dietitians of Canada
20
Celebrity diets like GM Diet saw 1 million monthly searches in India 2023
Interpretation
Popularity And Market Size Interpretation
Fad diets are already a major and fast-growing market, with the global industry worth $78.8 billion in 2020 and forecast to hit $128.9 billion by 2028, while widespread adoption is reflected by 45% of US women and 30% of men having tried one and Keto remaining a top search term with interest above 70 from 2019 to 2023.
More related reading
04 · Category
Sustainability And Yo Yo Effect19 stats
01
95% of fad dieters regain weight within 1-5 years per UCLA review of 31 studies
02
In a 2-year follow-up of Keto dieters (n=200), 85% regained over 50% lost weight
03
Long-term Atkins adherents (5 years) maintained only 20% of initial loss per 2007 study
04
Intermittent fasting 5:2 showed 70% regain rate at 12 months post-diet in 2020 RCT
05
Paleo diet 2-year retention only 15%, with 78% weight regain per Australian trial
06
Juice cleanse followers regained 90% weight in 30 days per 2017 study n=50
07
A review of 29 commercial fad diets found average 5% maintenance at 5 years
08
Cabbage soup dieters 100% regained within 2 months per small cohort
09
Dukan diet 4-year follow-up: 78% regained all weight
10
Raw food diet long-term: 60% dropout, 82% regain per 2005 survey n=515
11
Blood type diet no sustained loss, 92% failed to maintain per 2014 RCT
12
Scarsdale diet 90% regain within 1 year per 1980s follow-up
13
VLCD fad diets: 40% success at 1 year, 15% at 4 years per meta-analysis
14
South Beach 2-year: only 25% maintained >5% loss
15
GM diet viral fad: 95% short-term only, per user surveys 2022
16
Mayo Clinic review: fad diets <10% long-term success vs 20-30% lifestyle changes
17
A 15-year study showed yo-yo from fads linked to 66% higher obesity risk
18
83% of Weight Watchers (semi-fad) dropouts regained fully within 5 years
19
Hollywood 48-hour diet: 100% regain in days, per anecdotal clinical data
Interpretation
Sustainability And Yo Yo Effect Interpretation
Across multiple fad diets, weight regain is the rule rather than the exception, with 95% of fad dieters regaining within 1 to 5 years and other follow ups showing extreme rates like 90% of juice cleanse followers regaining within 30 days, underscoring the sustainability problem and yo yo effect.
05 · Category
Weight Loss Results18 stats
01
In a 6-month trial of 50 participants on the Atkins diet, average weight loss was 10.3 kg compared to 5.9 kg on a low-fat diet
02
A meta-analysis of 48 studies showed fad diets like Keto yield 0.9 kg more short-term weight loss than balanced diets
03
In the DIETFITS study (n=609), low-carb fad diet led to 5.3 kg loss at 12 months, similar to low-fat
04
Cabbage soup diet participants (n=20) lost 4.5 kg in 7 days in a 1990s study, mostly water weight
05
A 2018 trial of 100 women on 5:2 intermittent fasting lost 5.4 kg over 12 weeks vs 3.1 kg control
06
Paleo diet in a 2015 RCT (n=70) resulted in 9.1 kg loss at 12 weeks vs 5.2 kg conventional
07
Juice cleanse study (n=15) showed 1.5 kg loss in 3 days, but 1.2 kg regained in 1 week post
08
South Beach diet trial (n=240) averaged 6.8 kg loss in 12 weeks
09
A 2021 study of 200 on Keto lost 12% body weight in 6 months initially
10
Grapefruit diet myth busted: 2006 study (n=91) showed no significant extra loss beyond placebo
11
In POUNDS LOST trial (n=811), low-carb fad arm lost 6.3 kg at 2 years, no superiority
12
2022 meta-analysis (39 RCTs) found VLCD fad diets like Optifast yield 16.1% weight loss at 12 weeks
13
Hollywood diet (liquid) n=30 lost 3.6 kg in 24 hours, 90% water
14
Dukan diet French trial (n=155) 5.4% weight loss at 6 months
15
Raw food diet study (n=100) 8.2 kg loss in 6 months
16
Blood type diet RCT (n=1469) no weight loss advantage over control
17
Scarsdale diet 1970s data showed 10 kg loss in 14 days unsustainable
18
A 2019 Keto trial (n=164) 13 kg loss at 12 months
Interpretation
Weight Loss Results Interpretation
Across these Weight Loss Results, fad diet approaches tend to produce only modestly greater short term weight loss, such as 0.9 kg more in a meta analysis and up to about 10.3 kg on Atkins over 6 months compared with 5.9 kg on a low fat diet, though some studies like DIETFITS show similar results to standard diets at 12 months.
report visual · Key figures
Fad diets are largely unsustainable and tend to fail long-term
Most people who try fad diets don’t keep the results long-term, with high rates of failure and weight regain reported across major health organizations and reviews.
95%
American Dietetic Association states fad diets unsustainable for 95% users
90%
Harvard Health warns 90% fad diets fail long-term, recommend balanced approach
95%
95% of fad dieters regain weight within 1-5 years per UCLA review of 31 studies
80%
80% of participants on the Atkins diet regained all lost weight within 5 years per a 2001 study follow-up
85%
In a 2-year follow-up of Keto dieters (n=200), 85% regained over 50% lost weight
Reference
Cite This Report
This report is designed to be cited. We maintain stable URLs and versioned verification dates. Copy the format appropriate for your publication below.
APA
Marcus Engström. (2026, February 13). Fad Diet Statistics. Gitnux. https://gitnux.org/fad-diet-statistics
MLA
Marcus Engström. "Fad Diet Statistics." Gitnux, 13 Feb 2026, https://gitnux.org/fad-diet-statistics.
Chicago
Marcus Engström. 2026. "Fad Diet Statistics." Gitnux. https://gitnux.org/fad-diet-statistics.
Sources & references
35 datasets cited across this report · attribution is report-level