How Does Exercise Impact Weight Loss?
Exercise for weight loss – Cardio.
In this article, we discuss the concept of physical activity and exercise, in relation to weight loss. The key phrases to familiarize yourself with here are; net energy balance, positive net energy balance, and negative net energy balance.
Energy intake vs energy expenditure.
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 ‘positive net energy balance’ occurs leading to weight gain. Weight loss is associated with a ‘negative net energy balance’ whereby, expenditure exceeds intake.
Weight loss occurs when energy expenditure exceeds energy input.
It should be noted however that, energy expenditure exceeding energy intake is only healthy if it occurs for a limited period of time specifically for purposes of weight loss. After the initial period of time, it becomes detrimental to health leading to health problems like fatigue, anorexia, and others. The aim for long term health results is to maintain a ‘net energy balance’ whereby, intake is proportional to expenditure.
Determining the frequency, intensity, duration, and type of activity done.
Energy expenditure depends on a number of factors which include; 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.
‘Net energy balance’ leads to maintenance of weight.
Let’s examine energy intake or energy consumption. If a certain amount of food containing approximately 300 kilocalories of energy is consumed, the energy intake from the consumed food is equal to the energy expedited by moderate walking for 30 to 60 minutes at three miles per hour. If an individual walks for an ‘hour’ at three miles per hour, they will expend approximately 300 kilocalories, the same as what was contained in the consumed food.
If an individual walks ‘daily’ for one hour at approximately three miles per hour, while consuming the same 300 kilocalories of energy daily, this type of activity would lead to a ‘net energy balance’. In a state of ‘net energy balance’, no weight is gained and no weight is lost but rather, it is maintained.
‘Negative net energy balance’ leads to loss of weight.
If the individual were to walk for longer e.g. one hour, twenty minutes, without increasing food consumption, they would then enter into a phase of ‘negative net energy balance’ and thus weight loss. The same is true if the individual were to walk for the same duration (one hour) but faster e.g. walking four miles per hour instead of the usual three miles per hour.
If increased duration or pace where to continue for a period of time, without an increase in energy intake or consumption for; say two to four months, body weight would substantially be reduced. The weight loss is the result of a ‘negative net energy balance’ which is a product of energy expenditure exceeding energy intake.
Reaching the plateau: Decreased body weight also leads to decreased workout resistance.
After the initial weight loss however, if the individual continues to follow the same routine as depicted above, weight loss gradually ceases to occur. Individuals are often frustrated and surprised that the weight is not continuing to decrease, despite the continued routine. What has happened here is that, they have reached a plateau.
The reason behind the weight loss plateau is that, with decreased body weight, also comes decreased load when doing exercise. This means that, walking at a certain pace, for a certain distance a day, won’t have the same effect when carrying a reduced load as it has with a heavier load. If the discouraged individual quits their routine altogether, the weight is gained again at a quicker pace.
Weight gain is a result of a ‘positive net energy balance’.
The weight is regained as a result of a ‘positive net 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.
Going past the weight loss plateau.
The weight maintenance is the result of a ‘net energy balance’ being established within the body. This is energy intake, equating to energy expenditure. If there is no change in the ‘net 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’ and thus weight loss. 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 exercise.
Continued exercise and increased resistance.
In summary then, weight loss plateaus are expected, and can only end with continued exercise, and a ‘negative net energy balance. Stopping exercise or increasing calories will lead to weight gain. If one continues to exercise to maintain a ‘negative net energy balance’, weight loss will be promoted.
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