Nancy A. Melville
August 06, 2019
In new research, people who were obese showed significantly heightened perceptions of initial food satisfaction, whereas the gradual reduction of satisfaction that is typical with increased consumption — in this case, of chocolate — occurred at a slower rate compared with persons of normal weight and persons who were overweight.
"Our finding that obese participants, on average, tended to report a greater level of taste perception for a given quantity of chocolate than nonobese participants may, in part, explain why obese people consume more than nonobese people," said lead investigator Linnea A. Polgreen, PhD, in a podcast of the Journal of the Academy of Nutrition and Dietetics, which published the study July 30.
"If our findings are generalizable to other food, they may help inform future interventions," said Polgreen, who is an associate professor in the Department of Pharmacy Practice and Science at the University of Iowa, Iowa City.
The randomized study included 290 adults. Participants were provided with samples of chocolate one piece at a time and were asked to rate their perceptions of the chocolate on a scale of 1 to 10.
There were no limitations on the amount the participants could consume. To facilitate the evaluation of how perceptions changed with increased consumption, the participants were asked to eat as much as they could without feeling uncomfortable. About half (n = 150) were provided with nutritional information on the chocolates.
For 161 participants, body mass index (BMI) was normal (<25); 78 participants were considered overweight (BMI, 25 to <30); and 51 were obese (BMI, ≥30 or higher). Eighty percent of the participants were women. Ages ranged from 18 years to 75 years.
Although the taste perceptions were nearly identical for the normal and the overweight participants, those who were obese reported significantly higher perceptions of initial taste (P = .02).
Overall, the obese participants rated the samples approximately 0.5 points higher on the 10-point scale than the nonobese participants rated them.
The decline in perceived taste that occurs relative to the quantity consumed, an effect known as sensory-specific satiety, was about 2.0 points per sample overall but was significantly more gradual in obese compared with nonobese participants (P < .01).
The slower diminishment in taste perception could result in increased food consumption, first author Aaron C. Miller, PhD, an assistant professor in the Department of Epidemiology, the University of Iowa, said in a statement.
"Our findings indicate that obese participants needed to consume a greater quantity of chocolate than nonobese participants to experience a similar decline in taste perceptions," Miller said.
"Specifically, we found a woman with obesity would need to eat about 12.5 pieces of chocolate to fall to the same level of taste perception as a nonobese woman who ate only 10 pieces, which in our sample corresponds to a difference of about 67.5 calories. This may, in part, explain why obese people consume more than nonobese people," he said.
In the study, the amount of chocolates consumed ranged from as few as two to 51 pieces, although there were no significant differences between the groups in the amount of chocolates consumed. The mean consumption was 12.1 pieces (P = .36).
There were also no significant differences in the mean amount of time spent sampling the chocolates, which was 26.9 minutes in total and around 2.7 minutes per piece of chocolate (P = .28).
Women experienced more rapid declines in taste perceptions than men, with decreases of 0.09 additional points per sample for women compared with men.
There were no significant differences in taste perceptions among those who received nutritional information about the chocolates, a finding that is generally consistent with evidence suggesting that such information may not be as influential as expected, the authors note.
"We find that nutritional information, at least when provided for pieces of chocolate, had no effect on marginal taste perception," they write. "Thus, providing nutritional information alone may have limited effectiveness in reducing rates of obesity."
Taste perceptions were influenced, however, by hunger. Participants reported an increase of 0.13 in rating for each additional point on the hunger scale.
Whereas the vast majority of previous studies of sensory-specific satiety have focused on perceptions measured at the beginning and end of a meal, the new study is unique in observing instantaneous taste perceptions as well as how those perceptions change over time as more food is consumed, the authors say.
Study limitations include the fact that the participants were predominantly women and were volunteers recruited for the specific purpose of consuming chocolate. In addition, the results may not be generalizable to other types of food, such as those that are salty or bitter.
The findings nevertheless underscore potential benefits in focusing weight loss programs on the heightened food satisfaction that obese people may experience, the authors note.
"Indeed, strategies aimed at reducing obesity may need to account for differences in the perceived taste; strategies that work for normal weight or overweight individuals may not work as effectively for obese individuals if they derive more satisfaction from eating additional amounts of food," they say.
"For example, dieticians might advise obese patients to select or weigh out portions prior to beginning consumption to counteract the effect of difference in marginal perceptions.
"If marginal perceptions decline more gradually for obese individuals, stopping decisions may be delayed during a continuous period of consumption," they write.
In future studies, a key consideration should be the question of which comes first, obesity or heightened taste sensitivity, the authors suggest.
"Future work should also attempt to determine if differences in taste perceptions are a cause of obesity, or if obesity leads to higher levels of marginal taste from food," they say.
The study received no funding. The authors have disclosed no relevant financial relationships.