They lead to unwanted breath and body odour as the food takes longer than their healthier counterparts to get digested. Junk Food is high in hydrogenated oil, sugar, flour, salt and so are not good when consumed in excess.
The amino acids in meat leave a residue in your intestines during digestion. Intestinal enzymes break down that residue, which then mixes with bacteria on your skin during perspiration and intensifies your odor. It’s an effect that’s hard to avoid since meat is harder to digest than other foods.