Among the 100 participants (86 women and 14 men; mean [SD] age, 44 [11] years), the dropout rate was highest in the alternate-day fasting group (13 of 34 [38%]), vs the daily calorie restriction group (10 of 35 [29%]) and control group (8 of 31 [26%]).
https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2623528
An RCT comparing ADF, CR, and no-intervention control found that mean weight loss was not significantly different at 6 or 12 months between ADF and CR, but dropout rate was significantly higher in the ADF group [
22].
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5959807/
Dropout rates ranged from 0-65%. When comparing dropout rates between the fasting groups and continuous calorie restriction groups, no significant differences were found. Overall, the review did not find that intermittent fasting had a low dropout rate, and therefore was not necessarily easier to follow than other weight loss approaches.
https://www.hsph.harvard.edu/nutritionsource/healthy-weight/diet-reviews/intermittent-fasting/3/
A notable aspect of this trial was a very high dropout rate (38%) among the people assigned to the fasting regimen.
https://www.health.harvard.edu/heart-health/not-so-fast-pros-and-cons-of-the-newest-diet-trend
Drop-out rates were low but similar for both diet groups, suggesting participants found these similarly easy to stick to. Other long-term intermittent fasting studies in humans have shown similar results.
https://pubmed.ncbi.nlm.nih.gov/28459931/