They have certainly misunderstood this recommendation. They satisfy their hunger pangs but stuffing themselves with readily available commercial food, rich in calories but poor in nutrition. At times they also over eat to keep hunger at bay. This type of indiscretion increases the bulk of their body. This is harmful.
Blood oxygenation is impaired.
This also makes the heart work harder due to which breathing becomes laborious. Discouraging even the minimum of essential movements. This called degenerative arthritis or osteoarthritis. One of the most common complications of obesity is hypertension. Or high blood pressure.