Ensuring optimal health and maintaining a healthy body weight is accomplished through sound dietary practices and participation in regular amounts of physical activity. 

Energy Balance is the difference between the number of kilocalories that you eat (energy intake) and the number of kilocalories that you burn (energy expenditure). 

If energy intake is greater than energy expenditure than you are said to be in positive energy balance.  An individual in positive energy balance will gain weight. 

If energy intake is less than the amount of energy that is expended than you are said to be in negative energy balance.  An individual in negative energy balance will loss weight. 

If energy intake is equal to the amount of energy that is expended than an individual will maintain his/her weight.