Peyton Manning, LeBron James and Serena Williams are the highest contributors among the most influential athletes in marketing unhealthy food.

Fans often want to follow what their favorite stars do. The clothes celebrities wear; the food they eat, the beverages they drink and the music they listen to are often found to grow in popularity. The everyday life of a common man is highly influenced by celebrities.

In a study conducted on similar lines, researchers found that Peyton Manning, LeBron James and Serena Williams were the top contributors in promoting and marketing unhealthy food. These athletes are very fit and healthy themselves and when they advertise junk food or an unhealthy product, it sends out mixed messages about the product. People tend to attribute a sense of "healthiness" to this unhealthy product.

"We see these people - they've obviously (reached the top) of sports achievement, they're obviously living a healthy lifestyle - and they're endorsing these foods. And that kind of lends an aura of healthfulness to these foods and beverages that they don't deserve," said Emma Boyland, from the University of Liverpool in the UK.

Marie Bragg from the Rudd Center for Food Policy and Obesity at Yale University in New Haven, Connecticut led the study. She and her team compiled a list of advertising deals for 100 top athletes. Together, these athletes endorsed over 512 brands, of which almost half were food and beverage products.

Out of the 62 food products that were advertised including burgers, pizzas, cereals and cookies, 49 were low in nutritional value but high in calories. Similarly, among the 46 beverage brands that were endorsed by these athletes, 43 of them contained high levels of added sugar, which again is unhealthy.

"What stood out to us was the striking irony of the practice of having the world's most physically fit athletes endorsing these products," Bragg said.

What made these statistics all the more disturbing was the fact that most of these advertisements were viewed and followed by children and teenagers rather than adults.

"We know that children and (teens) are really affected by this type of thing," Boyland told Reuters Health. "We know that influences the type of foods they choose and they eat."

Boyland recommends that parents should be extra vigilant while choosing products that are advertised for children. Just because they are endorsed by athletes doesn't make them healthy.

Getting celebrities to endorse brands is a decade old selling tactic that continues to work even today. Manufacturers continue to pay celebrities, sportspersons and stars millions of dollars to endorse their brands and attract customers.

Kathleen Keller from The Pennsylvania State University in University Park claims that getting children to stop watching such ads on television is not enough to stop them from buying such food products. Parents should explain to children how advertisements work.

"Within your home you can really teach your kids from a young age about what the purpose of marketing is, what the purpose of advertising is," Keller said.

This is not the first time an athlete has been slammed for promoting unhealthy food. Earlier this year, in June, tennis superstar Maria Sharapova was accused of exploiting her stardom to sell her line of sugar candy named "Sugarpova."

Last year, the Academy of Royal Medical Colleges sounded the alarm over the London Olympics Committee selling the exclusive rights to peddle brand-name food and non-alcoholic beverages at the Games to McDonald's and Coca-Cola.

"Athletes, of all people, should know better than to promote these products," said Julie Greenstein, deputy director for health-promotion policy at the Center for Science in the Public Interest in Washington. "Athletes are heroes to most children and it's a shame that they're using their bully pulpit to sell obesity."

Peyton Manning and LeBron James earn at least $5 million annually from product endorsements. While Manning is popularly known for endorsing Papa John, James has been promoting brands like McDonalds and Coca-Cola.