Study Fat Consumption Is the Only Cause of Weight Gain in Mice - low fat...

Scientists from the University of Aberdeen and the Chinese
Academy of Sciences have undertaken the largest study of its kind looking at
what components of diet such as fat, carbohydrates or protein caused mice
to gain weight.

Since food consists of fat, protein and carbs, it has proven
difficult to pinpoint exactly what aspect of the typical diet leads to weight
gain.

Part of the problem is that it is very difficult to do studies
on humans where what they eat is controlled for long enough periods to work out
what are the most important factors, however studies on animals that are
similar to humans can help point in the right direction.

The study was published in the journal Cell
Metabolism, and includes 30 different diets that vary in their fat, carbohydrate
(sugar) and protein contents.

The mice were fed these diets for three months, equivalent
to nine years in humans.

In total over 100,000 measurements were made of body weight
changes and their body fat was measured using a micro-MRI machine.

“The result of this enormous study
was unequivocal, the only thing that made the mice get fat was eating more
fat in their diets," John Speakman, a professor who led the study, said.
“Carbohydrates including up to 30 percent of calories coming from sugar
had no effect. Combining sugar with fat had no more impact than fat alone.
There was no evidence that low protein (down to 5 percent) stimulated
greater intake, suggesting there is no protein target. These effects of dietary
fat seemed to be because uniquely fat in the diet stimulated the reward centers
in the brain, stimulating greater intake," Speakman continued. "A
clear limitation of this study is that it is based on mice rather than humans.
However, mice have lots of similarities to humans in their physiology and
metabolism, and we are never going to do studies where the diets of humans are
controlled in the same way for such long periods. So the evidence it provides
is a good clue to what the effects of different diets are likely to be in
humans.”