We’re a population of expanding proportions, but our increased appetite for television and trans fats isn’t all that’s to blame, according to a study in the International Journal of Obesity. Here are four other reasons our waistlines are expanding. Who knew?

1. Climate control
Thanks to the comfortable indoor temperatures provided by heaters and air conditioners, our bodies rarely have to work to warm up or cool down, so we burn fewer kilojoules.

2. Medicine
The pills you pop may affect your metabolism, hormone levels or appetite – all of which can add kilos. Culprits include antidepressants, antihistamines, antihypertensives, contraceptives, diabetic meds, mood stabilisers and steroids.

3. Older moms
A US study of nine to 10-year-old girls found that their obesity odds increased by 14.4 percent for every five-year increment in their mom’s age (researchers aren’t sure why).

4. Pollution
Chemicals that enter the air and water as by-products of manufacturing processes can mimic or block hormones like oestrogen – which can cause weight gain.