Why do we not crave healthy foods?Watch
All that sweet glucose gives us energy, since healthy food is relatively light on carbs it isn't as appealing to our bodies.
Foods high in fats and simple carbohydrates have the highest calorific intake which are most conducive to survival. We've evolved to make this rewarding through the release of hormones such as serotonin when consuming foods high in macronutrients. There are other factors such as the specific makeup of the microbiome in your gut; the more junk food you eat, the more you crave it in the future as bacteria best adapted to breaking these foods down outcompete others.
A sack of fried popcorn, or a huge sack of salad.
More often than not the rather large sack of salad is the winners choice.
If you eat foods too high in saturated fats and salt, your body is more likely to form multiple atheromas in the arteries. This is through a combination of two factors: high blood pressure (caused by a high concentration of salts in the blood so the body holds onto water to maintain homeostasis by dilution, called osmoregulation), which increases the likelihood of damage to the endothelium; and more rapid build-up of fatty streaks due to the increased concentration of lipids in the blood, which later hardens to form fibrous plaque. Fibrous plaque restricts blood flow by narrowing the lumen, raising blood pressure even further which creates a domino effect. Eventually, the blood pressure increases to a point where an atheroma bursts causing thrombosis - the formation of a blood clot by the action of platelets and fibrin. This can cause a total or near-total block of the coronary artery specifically, either through direct thrombosis in the coronary artery or the dislodging of a thrombus somewhere else in the body, which may travel to the coronary artery causing a blockage. The heart receives the oxygen it needs as a muscle (for respiration) from the coronary arteries, so when they're blocked, the heart cannot receive oxygen which causes myocardial infarction (a heart attack).