Serotonin and insulin
Here is how ingesting sugar -- or some carbohydrate that is broken down into sugar after digestion -- can alter our mood for the better. When we digest carbohydrates, our rise, and then insulin is secreted, lowering the blood levels of most amino acids with the exception of tryptophan, which is a precursor to serotonin. When there is more tryptophan than other amino acids, it enters the brain at a higher rate. The brain then produces more serotonin.
Serotinin is a substance found both in our brains and in our gastrointestinal tract. Serotonin has many functions. In the brain, it acts as neurotransmitter, and it helps to regulate mood.
Antidepressants are also called serotonin re-uptake inhibitors, preventing the supply of serotonin in the brain from going down. However, antidepressants are not the only way to elevate serotonin levels. Many ordinary people self-medicate when they are feeling depressed by eating lots of carbohydrates. We don't need a doctor to prescribe us a placebo. We crave carbs when we are feeling down, and eating carbs can be an effective means of elevating our mood. The problem is that the effect only lasts for a little while, and then the patient comes crashing down, in need of an even higher dose of carbs.
This is from a website that has even more details and explanations if you are interested.
Essentially, try to avoid and if possible completely remove these foods from your diet. There are plenty of substitutes for them, not to mention once you have stopped eating them for a certain amount of time, your body will stop craving them. Incorporate exercise to increase endorphins and happy hormones!! Your body will react!