The article is incorrect in assuming all single parent families are poorer than all two-parent families. A family with two parents working fast food jobs could easily make less income than a family with one parent working as a doctor. A better title for the article would be Low-Income Families have Fat Kids.
Regardless, I disagree with claiming low-income families have fat kids. The families have less money for food. As such, children in low-income families are more likely to be skinny and malnourished than fat.
Also, claiming a parent's inability to pay for school sport fees as an excuse for having fat kids is absurd. How much does it cost to go out for a walk? Last I checked, walking was free and the only cost involved was a pair of shoes.