The imbalance of the microbes in your intestine might effect your metabolism. This can have an effect on your weight and overall health. Studies done by Dr. Paresh Dandona show that eating fast food causes inflammation in your body. Chronic, low-grade inflammation can lead to diseases such as: diabetes, heart disease, stroke and certain cancers. Eating foods rich in vitamin C provide an anti-inflamatory effect, so eating foods rich in vitamin C can shield your metabolism and provide an anti-inflammatory effect.
This is a very interesting article that I highly recommend.
Click here to read the article in Mother Jones.