4. If you eat more energy your weight will increase. If you use more energy your weight will decrease. If the energy that you eat and use are the same your weight should stay the same.
5. You might have missed out something that you ate or something that you did.
You have estimated all the information – you could have made mistakes about the amounts and types of food and the length of your activities.
What you do and eat varies from day to day.
Your body uses energy for growth and to make heat as well.
You might have made mistakes in your calculations.