Eating only an apple and a boiled egg for breakfast is too little calorie intake, the total **** about 200 calories, easy to lead to hypoglycemia, long-term health is not good.

You can eat with buns, bread, noodles and other staples, to keep the total calorie intake to reach 30% of the body's metabolism is appropriate.

The average human metabolism requires about 1,800 calories for men and 1,500 calories for women, so a breakfast calorie intake of about 500 calories is the most appropriate.

Expanded information:

Calorie Requirements

Adults' daily calorie requirements = basic calories needed for the body's basal metabolism + calories needed for physical activity + calories needed to digest food.

Calories needed to digest food = 10% x (minimum calories needed for the body's basic metabolism + calories needed for physical activity)

Adults' daily calorie needs = 1.1 x (minimum basic calories needed for the body's basic metabolism + calories needed for physical activity)

Men: 9250-1000090 kilojoules

Women: 7980-8820 kilojoules

Note: Daily calories provided by food should not be less than 5000 kilojoules - 7500 kilojoules which is the minimum amount of energy required to maintain the normal life activities of the human body

Simple Algorithm of Basic Calorie Requirements for Basic Metabolism of the Human Body

Women: Basic Calorie (Kcal)=Body Weight (kg)x9

Men: basic calories (calories) = body weight (pounds) x 10

Reference: Baidu Encyclopedia-Calorie