Can eating only ground beef be unhealthy that means i eat nothing else ?

Nothing else?: Any diet that asks you to eat only one thing is bad from the start. Eat a balanced diet just like your mom said. Plenty of fruits and vegetables. Everything in moderation.

Varied diet. : Ground beef contains saturated fat, which we generally consider unhealthy. Even though carbohydrate-limited diets are all the rage in certain circles, they still have to be planned with great prudence. It would be better to maintain a varied, moderate-calorie diet containing lean proteins, complex carbs, fiber and a little bit of mono- and polyunsaturated fats. And exercise.