From Frugivore — As fasting has become popular through various religions and health diets, it’s also become a catalyst for inspiring eating disorders. While many testify that fasting is a powerful tool for spiritual growth, it is only healthy if done for a set period of time and reasonable purpose. If you are pursuing an absolute fast to lose weight, you’re not fasting; you’re crash dieting. While crash dieting and fasting have similarities, proper fasting requires research and the replacement of lost nutrients. Crash dieting is dangerous for numerous reasons, as it deprives the body of essential nutrients and limits our ability to function.
Often, crash dieting looks attractive to people whom want to lose weight quickly without putting in the necessary research, fitness regimen, and dietary plan. Simply put, crash dieting is not a sustainable solution for weight-loss since the pounds will immediately return once you resume eating regularly (and believe me, you will).
By not eating or drastically cutting down your food intake, you deprive your body of necessary nutrients, such as vitamins, minerals, proteins, carbohydrates, etc. When the body lacks nutrients, it depletes your immune system and also will cause you to feel weak. Eventually, you’ll find yourself with a limited ability to function and food will become appealing once again to re-energize.