Busy schedules, easy access to vending machines and the low cost of fast food all contribute to a growing population of obese children. According to the Weight-control Information Network, overweight children and teenagers are at a higher risk of developing serious diseases such as type 2 diabetes and heart disease, formerly conditions found primarily in obese adults. The culprits of the obesity epidemic are vast and include inactivity and unhealthy snack food.

Whole Milk

Milk and cookies have long been an after-school staple, which now is contributing to childhood obesity. Children need vitamins and calcium, but according to the Weight-control Information Network, whole milk is loaded with saturated fat.

The other part of the traditional after-school snack typically is made with loads of trans fats and unneeded sugar. Cookies made with hydrogenated vegetable oil and shortening contain some of the unhealthiest ingredients found in packaged food.

Soft Drinks

One 12-ounce serving of a sugary soft drink contains as many as 150 calories. Even children who eat healthy portion-controlled meals can spoil a day's nutrition with soft drinks. The Weight-control Information Network reports that soda and sugar-filled drinks are among the main causes of childhood obesity in the United States.

Potato Chips

Potato chips are easy to munch in large quantities when eaten directly out of the bag. According to Oregon Health & Science University, salty snacks such as chips are laden with fats and oils and provide more salt in one serving than children need in an entire day. High salt consumption leads to hypertension and water retention as well as obesity.

Chicken Nuggets

While parents may believe that a snack with chicken in its name is healthy, chicken nuggets are one of the worst snack foods. They are made with hydrogenated oils that make them easy to transport and reheat. Trans fats contribute to obesity, heart disease and cancer.

Candy

Candy that primarily consists of fat and sugar is a common daily snack in many households. Television shows often feature product placement that triggers cravings in children for candy, and parents too often relent.

Baked Goods

Pastries, muffins and donuts are common snack items that are full of trans fats, simple sugars and refined white flour, all ingredients that add to the childhood obesity problem. According to the Nemours Foundation, foods made of refined carbohydrates and simple sugars taste good and are not too filling, leading to over-consumption.

Ice Cream

Whole milk ice cream is full of fat and refined sugars that contribute to obesity. According to the Nemours Foundation, ice cream and other frozen desserts add an enormous amount of calories to a child's diet, and very few nutrients.

Cereal

Sugary cereals targeted to children are loaded with refined carbohydrates and sugar. According to a March 2010 article in "USA Today," most cereals for children contain as much as 65 percent more sugar than adult cereals.

Sandwich Crackers

Sandwich crackers contain ingredients such as cheese or peanut butter, foods that parents consider healthy. However, according to Keep Kids Healthy, sandwich crackers are among the most unhealthy snack foods prevalent in vending machines. One package of crackers typically carries more than 200 fat-laden calories.