Energy balance is the relationship between the calories we consume (energy in) and the calories we expend (energy out) through bodily functions and day to day activities. It’s governed by the laws of thermodynamics and fundamentally dictates whether we gain weight, lose weight, or maintain weight.
According to these laws, energy cannot be created or destroyed but is instead converted and transferred. When we consume food, we ingest energy stored in the form of calories or kcals, which is then allocated to three primary destinations: work (physical activity), heat production, and storage (fat reserve).
On the other side of the equation, energy expenditure refers to the energy required for basic bodily functions at rest, physical movements, and metabolic processes – digestion, absorption, etc.
Why is Energy Balance Important?
Aside from its effect on our body weight, energy balance plays a pivotal role in cellular processes and our overall health and I’ll explain this further shortly.
Negative Energy Balance
A severe negative energy balance can trigger a metabolic slowdown, decrease bone density, lower thyroid levels and testosterone levels, reduce physical performance and impair concentration. But a negative energy balance promotes weight loss by prompting the body to tap into its fat reserves to compensate for the energy deficit.
The body responds similarly whether facing a controlled diet in a luxurious setting or enduring food scarcity in less privileged circumstances—it adjusts by conserving energy and prioritizing survival functions over non-essential activities.
Positive Energy Balance
On the other hand, overeating or insufficient physical activity can lead to a positive energy balance, resulting in weight gain and possible risks to health and cellular function. Excess calories contribute to issues such as arterial plaque buildup, elevated blood pressure and cholesterol, heightened susceptibility to certain cancers and insulin resistance.
How GLP-1 Helps Achieve Energy Balance
Our bodies are constantly expending energy through various processes like basal metabolism, physical activity, and adaptive thermogenesis. Recent discoveries have highlighted the importance of adaptive thermogenesis not just for maintaining body temperature but also for keeping our entire metabolism in balance.
Adaptive thermogenesis kicks in when our surroundings get cooler than what our body considers as “comfortable.” At that point, our body starts using clever tricks to conserve heat, like tightening the blood vessels in the skin, raising hairs, and even changing our posture and movement patterns in its effort to reduce heat loss. When these tricks aren’t enough to keep our core temperature steady, our body resorts to two main strategies: shivering and non-shivering thermogenesis, which happen in a type of fat tissue called brown adipose tissue (BAT).
In BAT, there’s a special protein called uncoupling protein 1 (UCP1) that disrupts the usual energy production process in the cellular level. It creates heat instead of energy to help us stay warm when it’s cold outside. While brown fat cells can respond directly to signals from our body, like hormones, the main control over how much heat they produce comes from our brain.
Two important hormones, glucagon and glucagon-like peptide 1 (GLP-1 specialist), play significant roles in regulating BAT activity. Glucagon helps control our blood sugar levels by telling our liver to release stored glucose and stopping it from making more. GLP-1 medication, which is released after we eat, boosts insulin production and lowers the amount of glucagon that raises our blood sugar, and makes our liver less likely to make glucose.
How Energy Homeostasis is Maintained with GLP-1
Maintaining energy balance in the body involves a complex interaction between nutrients, neural signals, adipokines, and gut peptides. These components act by binding to receptors in the central nervous system (CNS) or peripheral nervous system (PNS). Signals travel bidirectionally between the gut and the CNS through pathways involving both the enteric and autonomic nervous systems.
This intricate system, known as energy homeostasis, is crucial for overall health. Disruptions in this balance are linked to conditions like obesity and diabetes. GLP-1 may have been initially thought to affect energy balance through its action on peripheral vagal nerves at normal levels but recent developments show that newer GLP-1 receptor agonists (GLP-1RAs) primarily induce weight loss by directly activating GLP-1 receptors in the brain.