This is not a law, yet. The BILL was introduced on Feb. 1. It will likely die on the floor.

not long

Though it's a bill now, the analysis as to its constitutionality would probably go something like this: The law would be challenged under the substantive due process (SDP) clause of the 14th Amendment. SDP basically requires that, when the government passes a law, the government has to have a good enough reason for doing so, as long as that law infringes on a life, liberty, or property right. Depending on the liberty interest that is involved, the court will apply different levels of scrutiny. If the liberty interest is "fundamental to ordered liberty," like the interest in one's own life or the ability to raise one's children, strict scrutiny is applied which requires a compelling governmental interest and means that are narrowly tailored to the ends. If it's just garden-variety liberty we're talking about, the court only requires a permissable goal and means reasonably related to the ends. Here, the goal of the legislature is to cut down on obesity. It's a valid extension of the state's police power, and it could be characterized as "compelling" due to the dire health risks of obesity. But what about the liberty interest? Is it "fundamental?" That probably depends on how you characterize it. Scalia would see the interest as "being served in a restaurant," which wouldn't be fundamental. However, some of the other supreme court justices look at liberty interests with a wider lens, and may see it as being free from a badge of inferiority, which may be seen as fundamental. The law probably would pass rational basis scrutiny, since there is a connection between limiting obesity (a valid gov. goal) and being served food. However, it probably wouldn't pass strict scrutiny, since the means are not narrowly tailored to the ends (since it doesn't stop obese citizens from buying a bunch of food at the grocery store, or just ordering take-out).