By Craig Weatherby
Conventional weight-control wisdom of the 1980’s called for cutting on back fat.
That makes some sense, since fat has twice as many calories as carbs or protein.
Then, that fad gave way to a low-carb craze triggered by the claims made for low-carb, Atkins-style diets.
Clinical trials find low-fat vs. low-carb diets about equally effective at weight loss and control – though low-carb has the edge.
Once again, low-fat food products are gaining popularity, with more people choosing “light” varieties.
But while low-fat foods contain fewer calories, they are less satiating, so people tend to overcompensate by eating more.
Fats satisfy about equally, omega-3s offer metabolic aid
Dietary fat makes us feel full and – like carbs – triggers satiety signals to the brain.
However, there’s no good evidence that different fats – saturated, monounsaturated, or polyunsaturated – affect satiety or calorie intake very differently (Strik CM et al. 2010).
That said, there is evidence that omega-3 fats boost the burning of body fat and curb appetite to modest extents (Harden CJ et al. 2012; Hibbeln JR et al. 2012).
Now, a clinical trial shows that among common fats, olive oil curbs appetite (satiates) and cuts calorie intake best.
Amazingly, its aroma appears to account for much of its ability to help control weight and body fat.
Olive oil found more effective than other fats
European scientists conducted a clinical trial to compare the effects of four different food fats or oils – lard, butterfat, canola oil, and extra virgin olive oil – on subjects’ appetite.
The participants were divided into five groups, with the volunteers in each group assigned to eat 500 grams (18 ounces) of yogurt every day for three months, in addition to their normal diet.
But each group got a different kind of yogurt:
- Fat-free yogurt
- Fat-free yogurt with lard
- Fat-free yogurt with butter
- Fat-free yogurt with olive oil
- Fat-free yogurt with canola oil
After three months, “Olive oil had the biggest satiety effect,” said Prof. Peter Schieberle of the Technical University of Munich.
“The olive oil group showed a higher concentration of the satiety [appetite-satisfying] hormone serotonin in their blood.” (TUM 2013)
Compared with the groups eating the three other fat-enriched-yogurts, the olive-oil-yogurt group found theirs more filling.
More importantly, no member of the olive-oil-yogurt group gained body fat or weight.
Similarly, the volunteers in the butter and control (no fat in the yogurt) groups reduced their caloric intake and did not gain weight.
In contrast, the canola and lard groups gained weight … and didn’t reduce their calorie intake.
This was surprising, given the similar fat profiles of olive and canola oils, which are both unusually high in monounsaturated fat.
Olive oil’s aroma is the key
To find out why olive oil worked so much better than canola oil, the team decided to test its aromatic compounds alone.
For this second part of the study, one group was given fat-free yogurt with olive oil aroma extracts and a control group was given plain fat-free yogurt.
The results were striking: The olive oil group’s calorie intake remained the same, but the control group (no olive extract in the yogurt) consumed an extra 176 calories per day.
As Dr. Schieberle explained, “The aroma group adapted their eating habits – but the control group participants were obviously not able to do likewise.”
“We also found that in comparison to the other group, the control group had less of the satiety hormone serotonin in their blood.” (TUM 2013)
Olive oil has least impact on blood sugar level
The duration of satiety after eating depends on many factors, but your blood sugar level is key … the faster it falls, the sooner hunger returns.
Accordingly, the researchers examined which of the aroma substances in olive oil are most effective at inhibiting glucose absorption.
They identified two “grassy” aroma molecules (hexanal and e2-hexenal) that reduced absorption of glucose, thereby slowing the normal post-meal drop in blood sugar.
“Our findings show that aroma is capable of regulating satiety,” concludes Schieberle.
Their discovery might pave the way for reduced-fat food products that kill two weight-control birds – fewer calories and reduced appetite – with one olive-scented stone.
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