No. Metabolism can’t get "ruined". Your internal organs use up to 80% of the calories you burn every day and they can’t function without energy or stop working, because you ate the wrong food or you didn’t follow the correct "metabolism boosting diet". The only person with a ruined metabolism is the dead person. Your metabolic rate can only slow down, it can’t get ruined or permanently damaged or anything like that. If you follow a very low calorie diet for a long period of time, you may experience a small drop in your metabolic rate, which is reversible. Your metabolism will recover when you start to eat normally again.