Some disturbing stats^1,2:

    -81% of 10-year-olds are afraid of being fat

    ->50% of 10-year-old females feel better about themselves if dieting

    -Almost half of 9-year-olds have dieted

Sadly, parents need to be on the lookout in their young children for signs of negative body image, dieting and even eating disorders.  Empower yourself by taking the following steps:

• No "fat talk" at home.  This means no bashing your body or that of others.  It also means not commenting positively about the body of others.  Any type of comment, no matter how well-intended, places value on a person's appearance as part of their self-worth.  Focus on other qualities instead.
• Stop dieting.  Even if you aren't talking about your own body dissatisfaction or dieting behaviors, kids are perceptive.  They notice when mommy doesn't eat the same thing as the family for dinner or when you scrutinize your thighs in the mirror. 
• Don't restrict the types or amounts of food you let your child eat.  Provide structured eating opportunities at meals and snacks, and serve a variety of foods.  If there are forbidden foods in your household the child will likely seek out and overeat these foods when given the opportunity at a friend or relative's house or other places.
• Be mindful of the types of entertainment you allow your child to engage with.  Certain games, toys or TV shows contain overt and/or subtle undertones of promoting the thin ideal for girls and the muscular ideal for boys.  Children are also being exposed to sexualized messages earlier than ever.  You as a parent get to decide if a toy/show/activity is inappropriate for your child.  This could be a huge "teachable moment" as you explain it to them.

References:

1. Mellin, Scully and Irwin, 1991

2. Mellin, Scully and Irwin, ADA Annual Meeting, October 1986