How our environment shapes our weight
The world we live in and the food we eat have dramatically changed over time. But our biology has largely stayed the same. It can trigger us to behave as though we’re at risk of starvation, and make us seek out food rich in energy, salt, fat, and sugar.
Think about our everyday life: most of us commute by car or public transport to work. We have elevators and escalators to take us where we need to go without a drop of sweat. Office jobs, working from home, and city life often mean that we have to sit more and for extended periods of time. We are surrounded by lots of tasty food and drink that we have easy access to. And there’s so much to worry about and catch up on — whether it’s at work, in our private lives, or on social media. So, we sleep less and stress more.
But not many of us are aware of how all these things are linked to developing overweight and obesity. In order to understand this, we need to travel back in time.
Our environment 50,000 years ago
“Eat or be eaten!” Imagine living 50,000 years ago in the Stone Age. All our ancestors cared about was chasing calories through hunting, gathering, or fishing. That, and avoiding becoming the meal of the day for large predators.
Food was scarce, so being well-fed meant a higher chance of survival, and a higher chance of reproduction. The key to success was getting hold of food with a lot of fat, sugar and salt. That’s why our bodies have learned to look out for and favour energy-rich foods to get through periods of famine.
Life changed – our biology did not
You might now think that we must be quite different from our ancestors. But the systems that helped them to survive are still active in our bodies today and often work outside our conscious awareness.
The impact of our environment on our weight
Food manufacturers, supermarkets, restaurants, and take-away chains have picked up on our food preferences. They now offer a huge variety of cheap, delicious and energy-rich foods that combine salt, sugar and fat. This is a powerful combination for our senses — far more powerful than our brains have evolved to deal with. That’s why it’s hard to resist the enticing smell of food we are now surrounded by.
We shouldn’t be surprised when we super-size our takeaway order or fill our shopping cart even though we aren’t hungry. Our ability to resist these deliberately tempting foods is determined by a range of factors, including our genetics, and varies from person to person.
So, the global rise in overweight and obesity is not the result of a sudden loss of willpower. Instead, weight gain is understood as a natural reaction to living in an environment that has changed faster than our species has been able to adapt to.
“In Aotearoa New Zealand, one in three adults (34.2%) were classified as obese in 2024/25, up from 31.3% in 2019/20.”
— New Zealand Ministry of Health (2025)
This information is provided for general educational purposes only and is not intended to constitute medical advice, diagnosis, or treatment. Always consult your healthcare professional for medical advice tailored to your individual circumstances.
