Associate Professor Russell Keast, Dr Jessica Stewart and PhD student Lisa Newman have found that eating a high fat diet can desensitise a person’s ability to taste fat in foods which may lead to overeating of fatty foods and subsequent weight gain. The study results are published in the International Journal of Obesity and Clinical Nutrition.
The latest study builds on the researchers’ discovery last year of a sixth taste that is responsive to the fat content of foods.
“Last year we revealed the results of a study that found fat can be added to the tongues taste repertoire, joining the other known tastes of sweet, salt, sour, bitter and umami (in protein rich foods),” Dr Keast said.
“What we have found now is that the taste buds of overweight and obese people are less sensitive to fat in foods and that this could be a reason for their overconsumption of fatty foods.”
For the current study, participants were placed on a low fat diet for four weeks and a high fat diet for four weeks. Their ability to taste fat before and after both diets was tested.
“We found that placing people on a low fat diet for four weeks significantly increased their ability to identify low concentrations of fat,” Dr Keast said.
“When the same people were on a high fat diet, the sensitivity to fat did not change in the overweight/obese people, whereas there was a significantly reduced sensitivity for those in the healthy weight range.
“This showed that overweight/obese people were insensitive to high levels of fat in the diet. It was interesting that we could improve fat sensitivity of overweight/ obese people with low fat diets – in a sense train their taste buds to be more sensitive to fat. This provides hope that their body may be able to adapt over a period of time, thereby responding to dietary fat in a similar way as a healthy weight person.”
Dr Keast explained that people insensitive to fat taste tend to consume more energy because their body does not tell them to stop eating.
“What is measured in the mouth reflects the body’s response to fats,” he said.
“Those who are insensitive to fat taste do not get the fullness signals. So, when consuming a fatty meal, a healthy weight person would start to feel full and stop eating and the gap between meals would also be extended. However, those who are insensitive to fat taste do not feel full and therefore keep eating and the gap between meals is also reduced.”
The researchers also found that people with a decreased sensitivity to fat ate more meat and high fat dairy foods.
“In our study the people with less sensitivity to fat taste ate significantly greater quantities of butter, meat and dairy. This finding leads us to believe that specific foods groups and perhaps different types of fats are associated with decreased sensitivity to fat in foods,” Dr Keast said.
The researchers are now running a study to determine if genetics play a role in fat taste perception. Anyone interested in taking part in the study can email [email protected] or phone (03) 9251 7286.