Energy Balance, Metabolism & Dieting

By Tayla Clegg (Athlete & Student Dietitian, SCU) &

Samantha Staines (ADP)

The term “Your body is a machine” is thrown around a lot when it comes to fueling your body. However, our bodies are in fact very far from a machine. Our bodies are highly complex and adaptive to our behaviours and environment, and this is particularly evident when we talk about energy balance, metabolism and dieting.

What is energy balance?

Energy balance is the relationship between energy intake, energy expenditure, and energy storage. The energy we take in is from the calories in our food and drink, whilst the energy we expend is used by the body for our daily energy requirements. In theory, if there is less energy expenditure than energy intake, this results in a positive energy balance, and generally a gain in weight. Alternatively, a negative energy balance occurs when energy expenditure exceeds energy intake, this is termed a negative energy balance, and generally leads to weight loss. Lastly, when eating the same amount of energy that your body requires, leading to the maintenance of body weight (1).

What are the impacts of dieting on metabolism?

As mentioned, a diet that achieves a negative energy balance, or “calorie deficit”, is necessary for weight loss. However, with this deficit, we also see metabolic and hormonal adaptations occur, that can may slow down weight loss or impact our capacity to reach certain weight loss goals. This is because our body has functions that aim to help us survive, and from an evolutionary perspective, losing weight is not beneficial to survival.

These adaptations as we mentioned, come from different systems of the body, including hormonal and metabolic processes, that play role a in regulating body composition, energy intake, and expenditure. Some of these impacts include: