Cite the evidence that supports the claim that artificial sweeteners cause weight gain. “Susan Swithers at Purdue University: Things that taste sweet would normally be things that providue us with energy. . .” Lab rats that ate more artifical sweeter gained more weight than those who ate sugar and they had “lower levels of a hormone called GLP-1, which affects how full we feel.” Scientists study how our bodies feel in relation to sugar and have found that our body prefers sugar.