Homeostasis is defined as “any self-regulating process by which biological systems tend to maintain stability while adjusting to conditions that are optimal for survival.[1]”
In other words, thanks to homeostasis, our bodies are able to maintain the correct internal conditions to keep us alive and well.
Energy homeostasis refers to your body’s attempts to maintain a stable weight, and proper energy balance. When you take in more energy than your body needs, it’s stored as body fat, and if you take in less energy than your body needs, you’ll lose weight.
Before we look at homeostasis impacts energy balance, and thus weight loss or weight gain, let’s look at why these systems matter.
Why is homeostasis important?
Without homeostasis, our bodies would have a very difficult time surviving.
For example, your body will attempt to maintain an optimal internal temperature for as long as possible. If you get hot, sweat is your body’s way to cool off. And if you’re cold, shivering is a fantastic way to generate some heat.
The human body regulates its internal concentrations of hydrogen, calcium, potassium, and sodium, as well as maintaining water, oxygen, pH and blood sugar levels–keeping these in balance is vital for survival, and we depend on our homeostatic systems to keep us alive and well. [2]
See this quick video for some more examples and information about why homeostasis is important:
By minimizing the risk of disease and death, homeostasis gives your body the best chance at survival.
What is the relationship between homeostasis and obesity?
Another function of homeostasis is energy regulation. Your body receives energy through food, and this energy is measured in calories. A calorie is not good or bad, it’s simply a unit of measurement, like an inch or pound.
Everything you do burns calories, whether it’s breathing, walking up a flight of stairs, or working out. Your body likes to maintain a stable weight, so if you’re taking in fewer calories than you burn, your body will send hunger signals to get you to eat. And if you eat too many calories, you’ll feel full.
The problem? Our modern society breaks the rules of homeostasis. We’re surrounded by processed, high-calorie foods, designed to make us continue to eat bite after bite, so many people end up eating more than their body needs, resulting in unwanted weight gain.
The hormones involved in hunger signaling, satiety (feeling full), and energy can get messy as well–let’s take a closer look.
Negative Feedback and Homeostasis
A critical aspect in homeostasis is the idea of a negative feedback loop–this is a reaction that causes a decrease in function. For example, if you’re hungry, your body senses a food shortage, and can decrease the amount of energy you’re burning to save energy.
Some researchers believe this negative feedback loop is the primary culprit behind the current obesity epidemic. [3]
This is a vicious cycle, and continues to make obesity worse. According to this theory, when someone is overweight, they’re likely to experience higher levels of body dissatisfaction, which causes them to eat even more as an emotional response.
According to this theory, the more that people suffering with obesity eat, the worse their body image becomes. If these people attempt to restrict food intake in an effort to lose weight, they only increase hunger and cravings, making them eat even more food.
It’s not all negative–your body can also use positive feedback in homeostasis
If you’re not taking in enough energy, you’ll feel hunger, fatigue, and cravings, signs to get your body to eat more. You may also experience cravings for specific foods if your body is deficient in certain nutrients.
There’s another way your body can attempt to maintain homeostasis… it can call in the support of your endocrine system, which regulates and produces hormones.
How does the endocrine system maintain homeostasis?
While the negative feedback loop described above may certainly play a role in obesity, it’s impossible to say it’s the only cause.
Let’s look at hormones secreted by your endocrine system, particularly the hormones associated with body fat and hunger.
Thyroid hormone is heavily responsible for fat burning, and if you’re restricting your food intake to lose weight, your thyroid hormone output decreases in an attempt to conserve energy.
You also have hormones called leptin and ghrelin, which regulate appetite and fat burning. When dieting, your body wants to survive, so it alters leptin and ghrelin levels, increasing hunger and making fat loss even more difficult.
When you have excess body fat, your hormones are designed to reduce your appetite, but our modern food is engineered to taste way too good, causing us to ignore our body’s signals and overeat.
In conclusion…
Our energy homeostasis system, designed to help us maintain a healthy weight, struggles to keep up with our modern environment.
Our bodies evolved to survive, consume calories, and store them for later in the form of body fat. While this worked well for our ancestors thousands of years ago, who often struggled to find food, in our modern world, this system can easily work against us.
Obesity is very complex, and influenced by many factors, not just our homeostatic system. Healthy weight management should involve a focus on healthy foods, regular physical activity, and minimizing stress as much as possible.
References
- Britannica, The Editors of Encyclopaedia. “homeostasis”. Encyclopedia Britannica, 27 May. 2020, https://www.britannica.com/science/homeostasis. Accessed 21 January 2022.
- Modell H, Cliff W, Michael J, McFarland J, Wenderoth MP, Wright A. A physiologist’s view of homeostasis. Adv Physiol Educ. 2015;39(4):259-266. doi:10.1152/advan.00107.2015
- Marks DF. Homeostatic theory of obesity. Health Psychol Open. 2015;2(1):2055102915590692. Published 2015 Jun 29. doi:10.1177/2055102915590692
