 [ Symptoms ] i have an overactive bladder need advice [ Disease ] although its an interesting theory it is not supported by science lactose intolerance does not cause weight gain excess weight occurs when you eat more calories than your body burns in fact people with more serious gastrointestinal problems like ulcerative colitis or crohns have food rush through them and they tend to be underweight and sometimes malnourished the body does not seem to overcompensate