Among 538 clients of a Smokers Clinic who were treated with 2-mg nicotine chewing gum, 34 (6.3%) were still using the gum at one-year follow-up. This group represented 25% of lapse-free abstainers. At one-year follow-up, long-term gum users were using an average of 6.8 pieces of gum per day. Long-term gum users were similar to treatment failures in cigarette consumption and tobacco dependence, while "gum-free" successes were significantly lighter and less-dependent smokers. Long-term gum users used more gum during the four weeks of treatment than treatment failures, who in turn used more than the gum-free successes. It is suggested that for many the long-term use of gum was an essential ingredient of their success. Long-term gum users gained significantly less weight than other long-term treatment successes.
Peter Hajek, Paul Jackson, Michael Belcher. Long-term Use of Nicotine Chewing GumOccurrence, Determinants, and Effect on Weight Gain. JAMA. 1988;260(11):1593–1596. doi:10.1001/jama.1988.03410110101035