If you are in the United States, I highly suggest taking a look at Jamie Oliver's School Food Revolution and Jamie Oliver's Tray Talk. The first is pretty eye-opening about how unhealthy our school lunch programs were even as recently as just a few years ago. Whether it is because of Jamie Oliver, the first lady, both, or neither, things are getting better. The second link teaches how to evaluate individual programs, and even offers up information for you and your child to view and learn from together.
Additionally, it offers ideas about how you can advocate for changes in your school if you feel they are needed. You can then evaluate your individual school lunch program from there and decide based on your particular needs.
The site's faq provides these answers to your questions:
Are school meals nutritious?
School meals are healthy meals that are required to meet science-based, federal nutrition standards limiting unhealthy fat and portion size and requiring that schools offer the right balance of fruits, vegetables, milk, grains and protein with every meal.
On July 1, 2012, new federal nutrition standards for school meals went into effect. Under these standards:
No more than 10 percent of calories can come from saturated fat and schools must eliminate added trans-fat.
School meals must meet age-appropriate calorie minimums and maximums.
Schools must gradually reduce sodium levels in school meals.
Cafeterias must offer larger servings of vegetables and fruit with every school lunch, and children must take at least one serving.
Schools must offer a wide variety of vegetables, including at least a weekly serving of legumes, dark green and red or orange vegetables.
Milk must be fat-free or 1% (flavored milk must be fat-free).
Within two years, all grains offered must be whole grain.
Why should I encourage my children to eat school meals?
Providing students their choice of milk, fruits and vegetables, whole grains and lean proteins, school meals are a great value and a huge convenience for busy parents. School cafeterias offer students a variety of healthy choices and help children learn how to assemble a well-balanced meal. Parents can rest assured that there’s no super-sizing in school cafeterias because federal regulations require schools to serve age-appropriate portions.
How are school nutrition programs working to make healthy meals kid-friendly?
Children can be notoriously picky eaters, but school nutrition directors are always working to find new healthy recipes that children are willing to eat. Many conduct student taste tests and involve students in menu planning.
Schools and the foodservice industry are making student favorites more healthy, such as serving pizza on whole grain bread with low-sodium sauce and low-fat cheese. Students often don’t even notice the difference. School nutrition programs also work to incorporate culturally appropriate foods into their menus to meet the tastes of their diverse student populations, as well as provide alternative foods for students with dietary restrictions and allergies.