A person's insatiable appetite for greasy fried chips and other fatty foods can not be blamed on their genes, according to new research.
An Australian study of 44 set of twins has found a high-fat diet decreases the human body's sensitivity to the taste for fat, irrespective of body weight or genetics.
Essentially fat becomes "invisible" the more it is consumed, meaning more is needed to satisfy the body, explained Professor Russell Keast, Director of Deakin's Centre for Advanced Sensory Science.
"There's this idea that maybe some people are just not as good at sensing high levels of fat, and that they're born that way," Professor Keast said.
"But what we found is that genetics does not provide any protection against the dietary influence of fat. If we eat a high fat diet, we lose our ability to sense fat," he said.
For the study, funded by the National Health and Medical Research Council (NHMRC), one twin from each pair was randomly allocated to a low-fat diet (less than 20 per cent of their energy from fat) or high-fat diet (more than 35 per cent of their energy from fat) for eight weeks.
Those on the high-fat diet were encouraged to eat more dairy, meat and oil. But each consumed the same number of overall kilojoules and were monitored to keep within their normal weight range.
Their taste for fat was tested at the beginning, middle and end of the trial.
At each test, each twin was given three small unmarked cups of liquid, and had to identify which of the cups contained a fatty acid. If they were unable to do so, the concentration of fatty acid was increased.
At four and eight weeks, the twins on the low-fat diets were able to identify the fatty acid at a lower concentrations than their twin on a high-fat diet.
Professor Keast says fat is a macro-nutrient vital for survival but excess fat is problematic for human health.
"Things like extra virgin olive oil for example should be part of a healthy diet. The excessive consumption of high-fat foods is having a detrimental effect on fat sensing which can cause those flow-on effects like obesity," he said.
Deakin School of Exercise and Nutrition Sciences researcher Andrew Costanzo says fat should not account for any more than 35 per cent of total energy consumed if they want to lose weight.
"This won't change how much you like the taste of fatty foods, but instead, the small amount of fat that you do eat will make you feel fuller, quicker," he said.
The study is published in the American Journal of Clinical Nutrition.