That's the advice from researchers who say parents who lead by example can help cut the childhood obesity epidemic.
In a piece of research that would well be entitled 'Stating the beeping obvious' scientists said that children copy their parents' lifestyle habits.
And they found that obese youngsters were far more successful at shedding the excess pounds if their parents got in shape with them.
"We looked at things such as parenting skills and styles, or changing the home food environment, and how they impacted a child's weight," said study author Dr Kerri N. Boutelle at UC San Diego.
"The number one way in which parents can help an obese child lose weight? Lose weight themselves. In this study, it was the most important predictor of child weight loss."
Researchers from UC San Diego and the University of Minnesota looked at 80 parent-child groups with an 8 to 12-year-old overweight or obese child.
They participated in a parent-only or parent and child treatment programme for five months. The study focused on evaluating the impact of three types of parenting skills taught in family-based behavioral treatment for childhood obesity, and the impact of each on the child's body weight.
These were: Behaviours to help the parents lose weight and act as a role model, changes in the home food environment and parenting techniques (such as the ability to limit the child's intake).
The researchers found it was only when the parents slimmed down that the children consistently did likewise.
They concluded in the journal Obesity that doctors should focus on encouraging parents to lose weight to help their overweight or obese child in weight management.
"Parents are the most significant people in a child's environment, serving as the first and most important teachers," said Dr Boutelle.
"They play a significant role in any weight-loss program for children, and this study confirms the importance of their example in establishing healthy eating and exercise behaviors for their kids."
Recent figures suggests that around a third of children in the US and the UK are overweight or obese.