Shorter individuals have to be careful while eating, because they tend to put on weight faster.
Compared to taller individuals of the same age, gender, shorter individuals usually will have less muscles, and their body will use up less calories, they will have a lower metabolic rate.
So if their diet has the same number of calories as a person who is taller, and they lead a similar lifestyle, the shorter person is more likely to put on weight, especially when the excess calories are stored in the body as fat.
Hence a shorter person will have to exercise more and lead a more active lifestyle to prevent weight gain, compared to a taller person.