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The Basics of Energy Expenditure


I've had a few people at the studio asking about strategies to increase weight loss so I thought I'd write a short article covering off on some of the basics.

First thing you need to know:
To lose weight, you need to spend more than you consume. For most people, this means increasing your daily energy expenditure and decreasing your daily energy intake.

Daily energy expenditure (the calories we burn in a day) is divisible into two basic types, active (non-resting energy expenditure) and passive (resting energy expenditure). Active makes up about 30%, with the remaining 70% being passive. For example, an average 80kg male might have a daily energy expenditure of approximately 2000 calories, made up of 1400 passive and 600 active.

Active energy expenditure is the energy used (or calories burned) when we are moving, and this is the type of energy expenditure we have the most control over. Active energy expenditure includes exercise and non-exercise. Exercise expenditure includes sessions at the gym and any other intentional movement we engage in, for example, going for a run. Non-exercise refers to the activities of our daily life where we expend energy, such as walking the kids to and from school, mowing the lawn, hanging the washing, and whatever our day job entails. For the average person non-exercise expenditure makes up about 20% of active energy expenditure, the remaining 10% comes from exercise; however, this varies greatly depending on your daily routines. So in our 80kg male, 400 calories might be used in non-exercise activities, and 200 calories might be used in exercise.

Passive energy expenditure is the energy used by our body at rest and is the energy required to keep us alive. Our brain needs fuel, as do the involuntary muscles associated with our heart, lungs and digestive system. This passive or resting energy expenditure is referred to as our Basal Metabolic Rate (BMR). It is dependent on our gender, age, height and weight. This passive energy expenditure makes up about 70% of our daily calorie burn or in our example male, 1400 calories.

Of the four factors influencing our BMR, the only one we have control over is our weight. This is where we need to know another important fact or two:

Muscle weighs more than fat.
Muscle is more metabolically active than fat.

To increase our BMR we actually want to weigh more, but we want that weight to be coming from muscle, not fat.

This is where strength or resistance training comes in.

Strength training will increase muscle mass, which will, in turn, increase BMR. However, muscle mass is only part of one of the four factors influencing BMR. To achieve a sufficient increase in muscle mass to make a noticeable difference to your BMR is possible but takes time and dedicated effort.

There is a stack of other reasons why we should all be regularly doing resistance work though. Strength training makes bones strong, protects joints, minimises age-associated muscle mass decreases, enhances balance and helps protects against falls. That's just some of the health-related benefits, for more check out this article at the Conversation. Then there are the performance and aesthetic gains we get from lifting weights ; ) 

The most immediate way to lose weight is to increase your active energy expenditure. Remember, this is a combination of exercise and non-exercise so increase both if you can. Increase daily non-exercise activity by walking an extra stop before you catch the bus or taking the kids out for a bike ride. If you are at a desk all day, try to integrate more movement, do your meetings or phone calls while you walk, or climb the stairs instead of taking the lift.

When it comes to exercise, which is better for weight loss? Strength or cardio? The answer is they both are. Anything you do to increase your non-resting calorie expenditure is going to help with weight loss. A combination of both is ideal. For those of us who are time-poor, getting both done in the one session is a great way to amp up the calorie expenditure while getting the benefits of strength training.

Remember, every body is different, comparing yourself to others rarely helps. Consider your own goals and the resources you have available, and consult an expert if you want specific advice.