Losing 5kg in 3 days on a potato diet is unrealistic and potentially unsafe. Extreme and rapid weight loss is not sustainable and can have negative health consequences. Instead of resorting to crash diets, focus on long-term, healthy weight loss by adopting a balanced diet, portion control, regular exercise, and lifestyle changes. Consult with a healthcare professional or registered dietitian who can provide personalized guidance based on your specific needs and goals. Remember, slow and steady weight loss is more sustainable and beneficial for overall health.