The soft drinks don't just pile on the pounds because of the calories in them, they also alter the way your body burns fuel. Your muscles grow to 'prefer' sugar to fat as a fuel, and thus losing weight becomes harder.
Drinking sugary drinks could be even more harmful than previously thought, the study said.
Soft drinks alter the way our muscles burn fuel preferring sugar over fat which makes the pounds harder to shift.
And worryingly this effect lasts long-term which can raise levels of blood glucose leading to diabetes, the Daily Mail reported.
Dr Hans-Peter Kubis, of Bangor University, said: "This study proves our concerns over sugary drinks have been correct."
"Not only can regular sugar intake acutely change our body metabolism; in fact it seems that our muscles are able to sense the sugars and make our metabolism more inefficient, not only in the present but in the future as well," he said.
"This will lead a reduced ability to burn fat and to fat gain. Moreover, it will make it more difficult for our body to cope with rises in blood sugar," he added.
Kubis warned the drinks can compromise long term health and, when in need of refreshment, people should reach for water instead.
His researchers also showed isolated muscle cells identify and respond to the sugary diet, and switch how they use the fuel.
The move to an inefficient metabolism was seen in male and female participants who were lightly active, and drinking soft drinks for just four weeks.
These factors show that regular use of sugar sweetened soft drinks drives alterations in muscles similar to those found in people with obesity problems and type 2 diabetes.
In the study 11 people in their twenties took part in a sugar sweetened soft drink supplementation for a month and before and after had their blood and muscle tissue as well as their whole body metabolism and composition tested.
Genes and proteins important for fat and sugar metabolism were analysed and blood sugar and fats assessed.
As it turned out metabolism shifted towards sugar away from using fat, genes for inefficient sugar metabolism were activated and a particular factor which is known to be crucial for genes of aerobic metabolism was reduced. Moreover the subjects gained fat and blood sugar was elevated.
