North Americans eat too much of everything. Nearly every diet "works" because by cutting out some branch of food you generally end up eating less. The science behind meat v. carbs is a total edge case. We are talking and +/- 10% chances of premature cancer, or heart disease, or whatever other old-person malady we are trying to prevent today. What matters more than any specific food is not being fat. Eat less. Exercise. Be thinner. That will do far more to prevent premature disease than any specific diet.

Rather than a meat tax, I'd rather see better government support for healthy lifestyles. Employers give sick leave. They should also give exercise leave to prevent disease in the first place. (Mine actually does this, 4 hours per week paid exercise time.) And tax deductions for gym/fitness center memberships is the lease that could be done.