The Rhetoric of Reputation

I'm writing a proposal argument for Paper 3 as a column piece for the Daily Texan.
Claim: The U.S. gov't should enact a "fatty foods" tax.
Reasons: Obesity and Overweight percentages are sky rocketing over the past few decades.
Warrant: A "fatty foods" tax would reduce the number of cases of obesity.
Backing: A British survey on a possible "fatty foods" tax reported that obesity rates would fall from the proposed tax. Also research shows that cigarette taxes caused a decline in new smokers and current smokers along with raising state revenue.
Objections: Many people think this would cause the price of healthy foods to rise and also people don't enjoy paying more taxes for anything pretty much.
Responses: A tax on fatty foods would actually cause an increase in suppliers of healthy foods, which creates more competition, which in turns leads to lower prices of healthy foods. As for paying more taxes, people need to understand the side effects of obesity such as a huge increase in health care costs from so many people getting diabetes, heart conditions, etc. A tax would eventually decrease these side effects so we could have lower health care costs and also state revenue's would increase so we could have better parks and such.