Sydney: A bad diet has consequences on the immune system which can lead to weight gain and other signs of obesity, a recent study has revealed. According to the study, published in the Journal of Immunology, the researchers studied the impact of a western-style high fat diet on the immune system and came out with two surprising results. "Our research looked at whether bad diets have consequences before we notice an increase in body weight. We found that over-consumption of saturated fats is a form of malnutrition: one that needs to be taken seriously," Abigail Pollock, a researcher at the University of New South Wales, said. The researchers examined the impact of dietary lipids on a class of immune cells -- T lymphocytes or T cells in which a diet rich saturated fats can impact immune function. "We fed mice a western-style high fat diet for nine weeks to observe if this diet would impact the T cell response before the animal gains weight. Despite our hypothesis that the T cell response would be weakened we actually saw the opposite: the percentage of T cells multiplying increased," added Pollock. One clinical ramification of overactive T cells may be autoimmune disease where the immune system begins attacking healthy parts of the body, suggested the study. According to the study, the other unexpected finding was that T cell responses were altered even in the absence of obesity and obesity induced inflammation. Dietary lipids do in fact directly influence T cell activation and responsiveness by altering the composition and the structure of the T cell membrane, suggested the study. "T cells are actually affected prior to the mice becoming overweight. Lipids in the diet change the abundance of lipids in the cell membrane, which in turn changes the structure of the cell altering the responsiveness of the T cells and changing the immune response," added Pollock.