сорваться ( если ты придерживался диеты, например) или же «развязаться» (если не употреблял алкоголь, и вдруг выпил))
сорваться (если ты придерживался диеты, например) или же «развязаться» (если не употреблял алкоголь, и вдруг выпил))
Editedto cheat on/break your diet (if you were dieting, for instance) or to fall off the wagon (if you stopped drinking, and then suddenly started up again)
По поводу диеты можно тоже сказать fall off the wagon.
to fail
"In summary, diets fail for a variety of reasons, including unrealistic expectations, lack of individualisation, restrictive eating, ..."
"Let's take a look at the most common reasons that diets fail and explores strategies to help you push through those barriers ..."
to break a dietary rule
"Dieting encourages and all or nothing mindset, so if you do break a dietary rule, you're likely to feel like you've failed already and abandon ..."
to slip
"If you've put on weight during a holiday, or your healthy eating has just slipped a little..."
"A slip is a single unplanned use of alcohol or drugs."
"A slip, also which can also be known as a lapse, is a situation where someone has a very brief “slip” where they drink or use, but they stop quickly afterward, avoiding a full relapse into addiction. Usually, this happens when a person decides to use again but instantly regrets the decision."
Насчет алкоголя -- fall off the wagon
On the 3d day of dieting she slipped up
OOPS! SHE SLIPPED ON HER DIET - YouTube
Slipped up on your New Year diet? 'I lost 10st by cutting...
Хотя, похоже, имеются в виду только одиночные срывы