Excessive calorie restriction can lead to several dangers such as nutrient deficiencies, decreased metabolism, and potential for muscle loss. It may also cause fatigue, irritability, and other health issues like hormonal imbalances. Over time, extreme restriction can lead to an unhealthy relationship with food, resulting in eating disorders. Additionally, the body may enter a starvation mode, making it harder to lose weight and maintain energy levels. It is crucial to maintain a sustainable and healthy approach to weight management.