It’s hard to keep up with trends in fat. First, we were told it’s bad for us. Then, we learnt about ‘good’ fats and ‘bad’ fats. Then trans fats were the bogeyman of the decade. And now, the link between dietary cholesterol and heart disease is being questioned by some doctors. The recent craze for coconut oil - which is high in saturated fat - demonstrates just how much attitudes to fat have changed.
Regardless of current nutritional advice, many consumers still suffer from fat phobia and have embraced low-fat products. But whether or not these products are effective in losing or maintaining weight is a disputed matter. While it is true that they contain fewer calories, people tend to overcompensate by eating more if they do not feel satiated.
A new study conducted at Technische Universität München (TUM) and the University of Vienna has shown that natural oils and fats regulate the sensation of fullness after eating, with olive oil being the most effective.
Under the guidance of Professor Peter Schieberle of TUM and Professor Veronika Somoza of the University of Vienna, work groups studied four different edible fats and oils - lard, butterfat, rapeseed oil and olive oil - for their satiety properties. Over a period of three months, study participants ate 500 grams of low-fat yoghurt enriched with one of the four fats or oils every day as a supplement to their normal diet.
“Olive oil had the biggest satiety effect,” said Professor Schieberle, Head of the TUM Chair of Food Chemistry and Director of the German Research Center for Food Chemistry.
“The olive oil group showed a higher concentration of the satiety hormone serotonin in their blood. Subjectively speaking, these participants also reported that they found the olive oil yoghurt very filling.” During the study period, no member of this group recorded an increase in their body fat percentage or their weight.
“The findings surprised us,” admitted Schieberle, “because rapeseed oil and olive oil contain similar fatty acids.”
To unravel this mystery, the researchers turned their attention to a completely different type of substance: the aroma compounds in olive oil. One group was given yoghurt with olive oil aroma extracts and a control group was given plain yoghurt.
The results, says Professor Schieberle, were conclusive. The olive oil group’s calorie intake remained the same, but the control group consumed an extra 176 kilocalories each day.
“The aroma group adapted their eating habits - but the control group participants were obviously not able to do likewise,” said Professor Schieberle. “We also found that in comparison to the other group, the control group had less of the satiety hormone serotonin in their blood.”
“Our findings show that aroma is capable of regulating satiety,” Professor Schieberle concluded. “We hope that this work will pave the way for the development of more effective reduced-fat food products that are nonetheless satiating.”