I will disagree with you. When we had mass conscription in WW2, it was found that a majority of American Males of conscription age were malnourished. The causes are up for argument.
Our young men today are out of shape, fat, and not prepared for all things military (ie lack of team work). That’s a National Security issue, not the cooks in our schools.
Amazing how those malnourished troops managed to defeat Hitler. Interesting that you are using the same argument that was deployed to socialize Great Britain during the first half of the 20th century. Harold MacMillan (in The Blast of War) at one point observed how much bigger and better nourished American troops were than British troops. Nutrition is important, but it is an individual, not a government, responsibility.
http://www.socialismtoday.org/120/nhs.html