Low Fat, High Sugar "Diet" Products Contribute to Weight Gain: US Study

26 Apr 2017 --- A new study has underscored the idea that low fat, high sugar "diet" foods play an important role in unwanted weight gain. Researchers from the University of Georgia found that rats fed a diet high in sugar but low in fat increased body fat mass when compared to rats fed a balanced (rodent) diet. Moreover, the rats fed a high-sugar diet were more likely to experience a range of other health problems, such as liver damage and brain inflammation.

The rats fed a high-sugar, low-fat diet didn't consume significantly more calories than the rats fed a balanced diet, says the study's principal investigator, Krzysztof Czaja, an associate professor of veterinary biosciences and diagnostic imaging in UGA's College of Veterinary Medicine. 

"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 says.

Over a four-week period, researchers monitored body weight, caloric intake, body composition and fecal samples in three groups of rats. In addition, after four weeks, blood and tissue (gut, brain, liver and nodose ganglia) samples were taken for testing. One group of test subjects was fed 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. 

Liver fat accumulation was significant in the high-sugar, low-fat group, which Czaja warns is “a very dangerous situation, because the liver accumulating more fat mimics the effect of non-alcoholic fatty liver disease,” which can lead to liver scarring and cancer.

The unbalanced diets also induced chronic inflammation in the intestinal tract and brain, researchers found. Former studies in rats conducted by Czaja have shown that brain inflammation alters gut-brain communication by damaging the vagus nerve, which controls sensory signals, including the brain's ability to determine when one is full.

Previous studies by the same researchers found that unbalanced diets decreased the gut microbiome's bacterial diversity, and low-fat, high-sugar diets increased gut bacteria that are associated with liver damage.

The study was published online in the journal Physiology and Behavior under the title “Diet-driven microbiota dysbiosis is associated with vagal remodeling and obesity.”