Fast food is known for its large portions, low prices, high palatability, and high sugar content, and there’s evidence from studies in teens and adults that frequent fast-food consumption contributes to overeating and weight gain. (61–66) The CARDIA study, for example, followed 3,000 young adults for 13 years. People who had higher fast-food–intake levels at the start of the study weighed an average of about 13 pounds more than people who had the lowest fast-food–intake levels. They also had larger waist circumferences and greater increases in triglycercides, and double the odds of developing metabolic syndrome. (62) More research is needed to tease apart the effect of eating fast food itself from the effect of the neighborhood people live in, or other individual traits that may make people more likely to eat fast food.