Trying to find ways to cut calories? Think you are making the right choice when picking “reduced fat” choices? Scientists have discovered that fat substitutes confuse the body, gearing it up to receive calories that are never delivered.
Susan Swithers, professor of psychological science at Purdue University in the U.S., explained: “Substituting a part of the diet with a similar tasting item that has fewer or zero calories sounds like a common-sense approach to lose weight, but there are other physiological functions at work.
“These substitutes are meant to mimic the taste of fat in foods that are normally high in fat while providing a lower number of calories, but they may end up confusing the body.”
She added: “Tastes normally alert the body to expect calories, and when those calories aren’t present we believe the systems become ineffective and one of the body’s mechanisms to control food intake can become ineffective.
“When the mouth tastes something sweet or fatty it tells the body to prepare for calories, and this information is key to the digestive process.”
She described the study as “a reminder to not discount the roles that taste and experience with food play in the way the body’s systems work together”.
She and her colleagues made their conclusions after looking at how weight fluctuated in rats.
A control group was fed full-fat crisps for 28 days. The other group was first fed the full-fat crisps, and then switched to fat-substitute crisps.
After the four weeks the rats which had been switched to the ‘diet’ crisps weighed more and had more fatty tissue than those given the regular crisps all the time.
Professor Terry Davidson, who co-authored the study, published in the journal Behavioural Neuroscience, said: “We are looking at an animal model, but there are similarities for humans, and based on what we found, we believe that our findings question the effectiveness of using fat substitutes as part of a long-term weight loss strategy.”
Prof Swithers said they thought the dieting rats put on more weight because “learned signals that could help control food intake were disrupted”.
However, their study could not account for a major difference between dieting rats and dieting people: the rodents were not trying to lose weight.