This chart
https://statbase.org/data/mex-prevalence-of-obesity-among-ad...
Says that obesity was shooting up in Mexico before that. The obesity rate doubled in the 15 years before NAFTA. After NAFTA the rate doubled again in about 30 years. I can't really see any obvious change after 1994.
Are these numbers incorrect, or were you meaning some other metric of obesity or obesity epidemic?