For the purpose of weight loss, physical activity can reduce body fat and is more beneficial in combination with reduced intake of calories.
Physical activity also helps in the maintenance and control of weight.

The following are some variables when physical activity and calorie expenditure is considered:

time: the amount of time spent on physical activity affects the amount of calories that will be expended. For example, walking for 45 minutes will burn more calories than walking for 20 minutes.

Weight: the body weight of a person doing the physical activity also impacts the amount of calories used. For example, a 250-pound person will expend more energy walking for 30 minutes than a 185-pound person.

Pace: the rate at which a person performs the physical activity will also affect the amount of calories used. For example, walking 3 miles per hour will burn more calories than walking 1.5 miles per hour.
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