Did you ever try using a rule of thumb such as a half-glass rule or a two-fingers-from-the-top rule when pouring wine? Do this if you want to keep your weight in check. Sticking to a general rule of pouring just half a glass of wine limits the likelihood of over-consumption even for men with a higher body mass index (BMI) a study reveals. Researchers found that BMI affected how much men poured but had no influence on women. 'About 70 percent of the people in the study used the half-glass rule and they poured significantly less by about 20 percent.