The modern conveniences of life, like personal computers and extension phones, could be causing you to gain weight, suggests the Reebok Aerobic Information Bureau.

Psychologist Thomas A. Wadden of the University of Pennsylvania attributes as much as 7 pounds per year to using a computer rather than a typewriter. Keeping files stored in the computer means you don't burn calories getting up to fetch them. Ditto for extension phones, which save about 70 miles of walking a year, thus adding 2 pounds.