Modest Weightloss

In the late 1970's David Berkowitz, the self-proclaimed "Son of Sam" serial killer shot 6 people in less than a year. Almost all of his victims had long brown hair which led to a surge in women dying their hair blond, or buying a wig.

I'm wondering if this would apply to other things. If there was a sniper targeting morbidly obese people, would we see a rise in gym memberships?