What’s the first thing you do when you’re at the store, pondering a new food purchase? If you scan the nutritional label on the back, chances are you’re at a healthier weight than your friends who just indiscriminately throw food in the cart.There’s a good deal of data to back that up. In a study analyzing a large-scale National Health Interview Survey (NHIS) by the Centers for Disease Control and Prevention (CDC), the University of Santiago de Compostela found that women who read food labels weigh less than those who don’t.MORE: Calories On Restaurant Menus, UnderstatedIf this comes as no surprise to you, hear this: These cautious consumers weighed in at nearly nine pounds less, and thus had a substantially lower body mass index (BMI). Impressed yet?More women read labels (75%) than men (58%), and the weight effect is stronger for women (way to go, ladies). About half of city-dwellers look at the labels regularly—urban settings are the most food conscious.Other people who were more likely to pay attention to nutritional info? Those with high school and higher education (so you did pay attention in Health class!). On the flip side, smokers aren’t reading up on nutritional content as much as their smoke-free friends. One unhealthy habit often begets another.But no matter where you fall in these demographics, it’s easy to start making the simple effort of seeing what your food’s really made of.QUIZ: What Was In Your Diet Today?Foods without labels (fruits and vegetables!) are the gold standard, but when faced with a food label, the fewer the ingredients, the better. The exception? Stay far away from eats with any of these food felons listed in the beginning of the ingredients

  • Simple sugars– Anything that ends in “ol or “ose” are alcohols that turn into sugar quickly. Excess sugar weakens proteins in your body, directly aging your joints, arteries and immune system. Avoid more than 4 grams of sugar per serving.
  • Enriched, bleached or refined flour (stripped of its nutrients)- These carbs are turned into sugar in your bloodstream, fast.
  • Look for “whole grain” instead. It takes longer to be turned to sugar, staying in your intestines and keeping you full! If it’s not listed first, it’s not 100-percent whole grain.
  • High fructose corn syrup– This synthetic sugar doesn’t shut off your hunger signals, is linked to weight gain and weight-related diseases.
  • Saturated fat– Can raise bad cholesterol levels in the blood. Avoid having more than 4g of saturated fat in an hour.
  • Trans fat– Stay far away from this artificially-made fat. It can mess up your metabolism in such a way that it speeds the hardening of plaque in your arteries—big ager on your heart! Don’t let the term “partially hydrogenated vegetable oils” fool you

This is far from a complete tutorial on the nutritional label, but here’s one last tip to look out for: If the label is screaming that it’s “fat-free” or “zero trans fats,” then it may be loaded with sugar.MORE: Are Low-Fat Foods Making You Fat?