Foods containing artificial fat in place of real fat may not help people lose weight. It may, instead, make them gain more, a recent study published by the American Psychology Association suggests.
Researchers at Purdue University found that fake fats – synthetic fat substitutes used widely in low-calorie potato chips – may actually get in the way of people's efforts to lose weight.
The research that challenges conventional wisdom that foods using fat substitutes help reduce weight was published online in the APA journal Behavioral Neuroscience.
“Our research showed that fat substitutes can interfere with the body’s ability to regulate food intake, which can lead to inefficient use of calories and weight gain,” said Dr. Susan E. Swithers, a professor of psychology at Purdue and the lead researcher.
One such fat substitute is olestra, which tastes like fat but has zero calories and is often used in your favorite potato chips or cookies.
In this study conducted by Swithers along with another psychology professor at Purdue Dr. Terry L. Davidson, and former Purdue undergraduate student Sean Ogden, laboratory rats were fed either a high-fat or low-fat diet of chow.
Besides their regular diet of chow, half of the rats in each group were fed high-fat, high-calorie potato chips. The other half of each group of rats was fed high-calorie chips on some days and low-calorie chips on other days.
The results demonstrated that rats that were fed both high-calorie chips and olestra-containing low-calorie chips ate more, gained more weight and put on more body fat compared to rats that consumed only the high-calorie chips. This, however, was true only for rats that ate high-fat chow.
Rats on low-fat chow diet, regardless of the type of chip they ate, did not show significant difference in terms of quantity of food they ate, weight they gained and the general increase in body fat.
Another significant result was that even when the rats were no longer fed potato chips, the flabbier rats did not lose the extra weight.
Researchers explained these counterintuitive findings, saying that artificial fats tend to baffle our bodily functions.
“Our bodies make predictions on what to prepare to digest based on taste and how food feels in our mouth," Swithers said. When a food tastes fatty, our body gets a signal that a large number of calories are coming. It triggers metabolic reactions and various hormonal secretions anticipating fat, calories, and other food nutrients that it would process. Fake fats interfere with this regulation.”
“When we get cues that something is fatty, but no calories arrive – like with fat substitutes – our body gets confused," Swithers said. “This confusion can make the body stop preparing to digest fatty food when it does come.”
When no calories come, the body, in that “confused” state, converts calories into fat.
Similar findings and explanations were reported about the use of saccharine and other sugar substitutes.
Swithers, however, has said that it can be difficult to apply laboratory findings about rats to human beings, though their biological responses to food are similar.
The study also notes that use of fat and sugar substitutes has increased “dramatically over the past 30 years.” This has also been the period with an “increased prevalence of overweight and obesity.”
“Based on this data, a diet that is low in fat and calories might be a better strategy for weight loss than using fat substitutes,” Swithers said.