What specific foods should you limit/avoid and why?

Ice cream, bacon, potato chips, candy - all of these foods are guilty pleasures.  Yes, they definitely taste good, but what they’re made out of isn’t so great.  The truth is that such foods are unhealthy for us, and it is in our best interest to limit or ultimately avoid these tempting treats. Your parents or doctor may have already warned you about the main devil in food terms: sweets.  Many things we enjoy to eat and drink such as frosted donuts and sweetened beverages are just a few of many.  However, now the deeper question becomes why?  Why can’t we eat these foods?

The simple answer is that these types of foods have high levels of unhealthy sugar which may lead to or cause other problems.  Research proves that consuming sweets causes weak bones, obesity, tooth decay, and high caffeine levels.  Some specific sweets you should limit or avoid are soda, sugar, and artificial sweeteners.

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Another unhealthy culprit are foods that consist of high levels of trans fat and free radicals, such as fast foods.  These foods may not be sweet, but they lead to inflammation and weight gain.  The vegetable oils used in the process of making these types of food are extremely unhealthy.  Vegetable oils may sound healthy, but in actuality are worse than many other types of oils, because of the procedure in which they are made; the rapeseeds they are made from are overheated and treated with many chemicals. Additionally, the processed meats used in fast foods are high in calories, fat, and sodium levels.  In addition, some of these processed meats have preservatives which can change into toxic chemicals for your body. The free radicals found in these foods are basically abnormal atoms that causes oxidation. Free radicals contribute to heart attacks, stroke and cancers. Lastly, it is best to stay away from salty foods.  Foods with high salt levels may increase the risk of a stroke and cardiac failure, while draining calcium from your bones.  Even though you need some sodium to survive, the organic form is the best for you. 
          Another important thing to note is that there are two types of cholesterol: good and bad. Contrary to popular belief that cholesterol is bad for you, you actually need the good, healthy type of cholesterol to survive. The good type is HDL, or high-density lipids, and the unhealthy type is LDL, or low-density lipids. HDL cholesterol and LDL cholesterol both have basically the same thing; it’s just that HDL has everything compacted while LDL is a looser blob of everything. Both have chemicals that help cells grow and creates hormones, but the difference between them is huge. HDL’s are able to float freely in the blood, reaching wherever they need to go to do their job (usually the liver). On the other hand, LDL’s are blotchier and mover more clumsily. This causes them to clump up on the sides of blood vessels. This is minor at first, but slowly accumulates and puts your blood vessels at risk of getting clogged up completely. This leads to heart attacks and strokes. The only problem is that junk, unhealthy foods are filled with LDL cholesterol and barely have any good cholesterol, leading to heart disease and strokes.

The next time you pick up a sugary donut or a handful of chips, remember how it affects you on the inside.  It is okay to eat unhealthy once in awhile, but not all the time.  It is important to limit yourself and to know how to do so.

Source: www.healthassist.net/conditions/food-avoid.shtml
http://health.howstuffworks.com/diseases-conditions/cardiovascular/cholesterol/difference-between-ldl-and-hdl-cholesterol1.htm