Smith, a native of Danbury, Connecticut, graduated from Immaculate High School (Danbury), received a Bachelor of Arts from Harvard College in 1992, and a master’s in science education from Columbia University in 1993.

He attended Dartmouth Medical School, but completed the last two years of his medical education and graduated from the University of Chicago Pritzker School of Medicine.

In April 2007, Dr. Ian Smith launched the 50 Million Pound Challenge. The challenge is a national health initiative encouraging people to come together and take control of their health by getting fit, losing excess weight and turning back the deadly toll of weight-related diseases that threaten nearly half of Americans. The Challenge is a free campaign supported by national civic and health organizations. It is helping cities, civic groups, friends and families team up to help reverse the epidemic of excess weight and create a culture of healthier living.

Smith has written six books including The Fat Smash Diet, a 90-day diet program that focuses on "smashing" bad eating and exercise habits and establishing new healthy ones. His most recent book Happy was released in April 2010. Additionally, Dr. Ian's founded the 50 Million Pounds website. The website had developed a partnership with CVS among other companies.

In partnership with CVS/pharmacy, the 50 Million Pound Challenge will participate in a series of free community health events in urban communities across the country. CVS/pharmacy will host over 250 "To Your Health" fairs in Atlanta, Washington, D.C. and Philadelphia, providing comprehensive health risk assessments and screenings including diabetes, blood pressure, cholesterol and osteoporosis.

Dr. Ian has appeared extensively on various broadcasts including “The View,” “The Tyra Banks Show,” “Larry King Live,” “Anderson Cooper 3600,” “Showbiz Tonight,” and “The Verdict with Dan Abrams.” He has written for various publications including Time, Newsweek, Men’s Health, and the New York Daily News, and has been featured in several other publications including, People, Essence, Ebony, Cosmopolitan, and University of Chicago Medicine on the Midway.

In Dr. Ian's July 2010 Newsletter, off of his 50 Million Pounds website, it was revealed that he was appointed to the President's Council on Fitness, Sports & Nutrition. The President's Council on Fitness, Sports and Nutrition (PCFSN) is a committee formed to advise the President about opportunities to develop physical activity, fitness, sports and nutrition programs for all Americans regardless of age, background or ability.