Achondroplasia and other forms of dwarfism can lead to child obesity more easily than the average child. Also, if the gene is passed down by hereditary and both parents have the mutation, and the child has the double mutation genotype, the is a risk of death since the skeletal system is twice as weak.
In the photo above, the child on the left is a regular child and the one on the right has achondroplasia. You can visually see how it affects the body by looking at the difference.