There is a direct relationship between the amount of TV people watch and how physically inactive they are, a new study shows. The study monitored low-income residents in Boston, two-thirds of whom were overweight or obese. Participants used pedometers that documented inactivity associated with time spent watching TV. Physical inactivity contributes to weight problems that can lead to heart disease.

On average, participants watched over three-and-a-half hours of TV a day -- which equated to 520 fewer steps walked a day. Some participants watched over 14 hours of TV on weekdays and 19 hours on weekends -- with every hour spent in front of the TV associated with 144 fewer steps walked. Inadequate maintenance of low-income neighborhood parks and the danger of street crime are two big fear factors in keeping the participants -- mainly African-American and Hispanic women -- at home in front of the TV, report Harvard researchers.