The so-called "diet" products containing low or no fat may have higher amount of sugar and consuming them regularly could make you fat, new research warns.

The sugar-laden "diet" foods could also lead to liver damage and brain inflammation, said the study published in the journal Physiology & Behavior. "Most so-called diet products containing low or no fat have an increased amount of sugar and are camouflaged under fancy names, giving the impression that they are healthy, but the reality is that those foods may damage the liver and lead to obesity as well," said the study's principal investigator Krzysztof Czaja, Associate Professor at University of Georgia in the US.

Researchers found that rats fed a diet high in sugar but low in fat - meant to imitate many popular diet foods - increased body fat mass when compared to rats fed a balanced rodent diet.  The high-sugar diet induced a host of other problems, including liver damage and brain inflammation. "What's really troubling in our findings is that the rats consuming high-sugar, low-fat diets didn't consume significantly more calories than the rats fed a balanced diet," Czaja said. 

"Our research shows that in rats fed a low-fat, high-sugar diet, the efficiency of generating body fat is more than twice as high - in other words, rats consuming low-fat high-sugar diets need less than half the number of calories to generate the same amount of body fat," Czaja added. Over a four-week period, researchers monitored body weight, caloric intake, body composition and fecal samples in three groups of rats.  One group consumed a diet high in fat and sugar, another group was fed a low-fat, high-sugar diet and a third group was given a balanced or "normal" diet.

Both the low-fat, high-sugar and high-fat, high-sugar groups displayed an increase in liver fat and significant increases in body weight and body fat when compared to the balanced diet group.