How Does Exercise Impact Weight Loss?

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in this animation we discussed the

concept of physical activity and

exercise as they relate to obesity in

humans there is a fine balance between

energy intake and energy expenditure

energy intake is in the form of food and

energy expenditure is in the form of the

basal metabolic rate and physical

activity the difference between energy

intake and energy expenditure is the net

energy balance if intake exceeds

expenditure then a net positive energy

balance occurs energy expenditure

depends on a number of factors this

includes the starting body weight the

basal metabolic rate and physical

activity with regard to physical

activity there are several key variables

including the frequency intensity

duration and type of activity done let

us examine energy consumption 1 honey

glazed donut is shown which has

approximately 300 kilocalories the

energy intake from the consumed donut is

equal to the energy consumed by moderate

walking for 30 to 60 minutes at 3 miles

per hour if an individual walks for an

hour at 3 miles per hour they will

expend approximately 300 kilocalories

the same as what was contained in the

consumed donut

if an individual walks daily for one

hour at approximately 3 miles per hour

this type of activity would lead to

weight loss this assumes that the

individual does not consume any extra

calories and has a net negative energy

expenditure if this continues for a

period of two to four months body weight

is reduced as depicted the initial

weight loss is the result of a negative

net energy balance the negative energy

balance is because energy expenditure

exceeds energy intake after the initial

weight loss the individual continues to

do the same type of exercise that is one

hour of moderate walking daily the chart

depicts changes in body weight over time

individuals are often frustrated and

surprised that the weight is not

continuing to decrease despite regular

walking they have reached a plateau the

reason behind the weight loss plateau

is that with decreased body weight the

basal metabolic rate also decreases when

the basal metabolic rate decreases there

is a decrease in total energy


if the discouraged individual quits

their daily walking exercise the weight

is gained again at a quicker pace

the weight is regained as a result of a

positive energy balance being created

energy expenditure is now less since the

physical activity has been stopped by

keeping the same intensity and duration

of walking without making any changes in

the diet energy intake the individual

would enter a weight maintenance phase

this is characterized by gaining a small

amount of weight the weight maintenance

is the result of an energy balance being

established within the body where energy

intake essentially equals energy

expenditure if there is no change in

energy balance there will not be any

further change in weight what must be

done to end the weight loss plateau

several options exist to maintain a

negative net energy balance these

involve either decreasing energy intake

or increasing energy expenditure options

include restricting calories further or

increasing the frequency or the

intensity or the duration of the


in summary then weight loss plateaus are

expected and can only end with continued

exercise and a net negative energy

balance stopping exercise or increasing

calories will lead to weight gain if one

continues to exercise to maintain a net

negative energy balance weight loss will

be promoted