RESULTS. A total of 872 children, 11.1% overweight and 82.8% white, were included in the analysis. Children of authoritarian mothers (n = 298) had an increased risk of being overweight, compared with children of authoritative mothers (n = 179). Children of permissive (n = 132) and neglectful (n = 263) mothers were twice as likely to be overweight, compared with children of authoritative mothers. Of the covariates, only income/needs ratio was significant and did not alter the relationship between parenting style and overweight risk.
Here's an article that explains the parenting styles.
The effects seem pretty large to me, but I don't know whether the study had enough people to be statistically significant.
The culture generally seems to believe that people are fat because they aren't treated harshly enough, and I collect every clue I can find that the culture is generally composed of cruelty addicts.
Info about the story found at The Agitator. I hunted down the abstract myself. The Agitator is mostly about government outrageousness, with a recent emphasis on evil SWAT teams, but there's also some fat acceptance.