Your fiancé proposed because he loves you, not because he expects you to squeeze yourself into a wedding gown designed for Twiggy. In fact, he'd probably be worried and even a little angry if you embark on a diet plan that can stress your heart, cause palpitations and dehydration, and torpedo your immune system -- all of which are possible side effects of crash dieting.
Need some hard evidence? According to Health.com, the U.S. Food and Drug Administration (FDA) examined 60 deaths of liquid-only dieters, many of whom were healthy people who suffered ventricular arrhythmias likely caused by malnutrition and stress to their respective hearts. Bear in mind, there are many more case studies out there -- this is just one report!