Who knew? How weight within the human body is regulated

It’s an all-too familiar story. You go on a diet, lose weight then… put on even more weight down the track. Or worse, you eat less, exercise more but the weight won’t budge.

What gives?

Yep, our bodies are complex. 

So how does the human body regulate weight?

Well, it’s a mix of genetics (thanks mum and dad!), physiological factors, that is, how our body parts function, and behavioural factors. 

Behave! How behavioural factors affect our weight  

Behavioural factors are as varied as Kimmy K’s shoe collection. Some of the more common weight affecting behaviours might be:

  • How much sleep you get. If you don’t get enough sleep your body can’t function optimally. Find your perfect ‘well rested’ number – 6 to 8 hours is the average!
  • How much exercise you do. You can’t burn calories binge watching Vikings for weeks on end!
  • Eating behaviours. This includes whether you have a healthy diet that fuels your body with healthy nutrients, your alcohol consumption (most of us know how a hangover affects our brain and body the next day!) and when you eat. For example, brekkie is the most important meal of the day, giving you the fuel – or energy via kilojoules – to kick start your brain and body functions. Likewise, dinner should be eaten three hours before sleeping, so your body has time to digest your food before sleeping. Keep bed time for the ‘sleep and recovery phase,’ which is when the body heals itself and performs other essential functions, like absorbing the information you learnt through the day!
the five food groups
Choose foods from the five core food groups – vegetables and legumes; fruit; grains; milk, yoghurt, cheese and alternatives; lean meat, poultry, fish, eggs, nuts, seeds. Plus, small amounts of healthy fats. (Credit: Getty)

Let’s get physical! How physiological factors affect our weight

If only our body’s bits and bobs could talk. Wouldn’t life be so much easier if our digestive system just told us, ‘Hey, I’m having trouble breaking down the food. Eat more fibrous foods, please!” Imagine all the time and stress we’d save?! But alas, they can’t talk. They communicate with actions instead. And when it comes to weight regulation, our hormones speak the loudest through actions!

Hormone mayhem: how our hormones regulate our body weight

Our hormones are major game changers when it comes to weight loss, weight gain and weight stability. They influence our hunger, eating behaviours, how our body stores fat and much more. The main hormone players are leptin, ghrelin and insulin – and understanding how these guys work can make weight management a whole lot easier.

  • Leptin

Leptin regulates how much fat we burn or store and our hunger.  Leptin travels to the brain, which determines whether the leptin levels are too high, too low or just right (just like Goldilocks), and makes decisions based on this. For example, high leptin levels will (typically) increase your metabolism and therefore burn more energy. Over time, leptin also teaches you to recognise the signs that you are full, preventing overeating. So if you need to undo a button after dinner because your belly is bloated, that could be your leptin talking!

However, studies suggest that people with obesity may be ‘leptin resistant’, which prevents the hormone from doing its ‘weight management’ job.

  • Ghrelin

This hormone increases when you are hungry (and your stomach is verging on empty). If you have ever fasted then later devoured a pack of chocolate biscuits come nightfall, you’ll recognise this ‘hunger’ hormone – and its persuasiveness!

  • Insulin

Insulin plays many important roles in weight management. One of insulin’s biggest jobs is to maintain the body’s current weight and keep everything in balance. So if you suddenly stop eating carbs, insulin will react. How? By slowing down your metabolism and saving kilojoules for essential body functions, like the organs, brain, muscles, blood and cells. In other words, you will burn less calories, making weight loss even harder.

Get your doctor on side

There are many other physiological factors that can influence how our body regulates weight. If you are struggling to maintain a healthy weight, get your doctor on side. Your GP can investigate possible health conditions which affect weight management, such as Polycystic Ovary Syndrome (PCOS), thyroid conditions, insulin resistance, cortisol and hormone imbalance. Additionally, obesity can lead to a range of chronic health conditions, including heart disease, cardiovascular disease, gallbladder disease and more, according to the Australian Institute of Health and Welfare.

Your doctor can support you through your weight management or weight loss journey, with diet and exercise advice, and expert guidance about other weight loss solutions.

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