Today, 60% of Australian adults are classified as overweight or obese. By 2025 that figure is expected to rise to 80%.Many point the finger at sugar - which we're consuming in enormous amounts - and the food and drink industry that makes and sells the products fuelled by it.Despite doctors' calls for urgent action, there's been fierce resistance by the industry to measures aimed at changing what we eat and drink, like the proposed introduction of a sugar tax.On Monday night Four Corners investigates the power of Big Sugar and its influence on public policy.