Explain what liquid diets fasting and diet pills have in common

The answer is: they are not the right ways to lose weight.

All of these methods are not healthy because they don't have enough essencial nutrients, they contain chemicals / irregular ingredients and makes our metabolism slow down to save energy.

They can make people lose weight because they are cutting drastically their calorie intake but it can't be maintained forever. Most likely people will regain the weight lost after ending this diets.