The Government has not written off a "sugar tax" as a way of driving down childhood obesity, celebrity chef Jamie Oliver has said.
Oliver told MPs at the Commons health committee that Prime Minister David Cameron was reviewing all the evidence, adding there was a need to "maker sure he's brave".
He said his main role in front of the committee was "as a dad".
Of the need for a "sugar tax" and the Government's view, he said: "The discussions that I've had have not implied that that is written off.
"The discussions I've had are robust...Mr Cameron is reviewing everything.
"I think where he is positioned for the next five years...we need to make sure that he's brave."
He added that public polls on the need for a "sugar tax are favouring it quite strongly".
Asked what he would like to see in the Government's forthcoming obesity strategy, Oliver said: "I think my passion having worked with the British and international public for 17 years and having daily communications and monthly communication with millions of parents out there - is clarity.
"Honesty and clarity would be a really good balance.
"I don't believe the industry, particularly the food and drink industry, I don't think that utter clarity is their main objective because when you inform the British public with good, clear information they make good choices.
"They are not making good choices at the moment largely. I think it's a major problem."
Oliver said that before the general election there had been "no conversation" about the possibility of a tax.
He added: "I deeply feel passionate that parents of Britain and people involved in public health need to hold Mr Cameron to be brave and strong and support him otherwise the easiest thing, like minimum pricing on alcohol that had all the signs behind it, turns into a big old fight, they get burnt, they back off, they retreat when actually they were trying to do the right thing for public health."
Oliver said one of the most important thing was a government "that's willing to fight tooth and nail for public health and child health."
He added: "I do believe we need one strong hard action to be made, that is the sugar tax, and everything else will cascade off that beautifully."
Oliver said he believed the Government was still open to a tax and that Mr Cameron sees the issue of childhood obesity as "very important".
On industry, he said: "A tax does remind them who's boss, and that is child health and the Government."
Cereals, sugar-sweetened drinks and highly-processed foods "are major contributors in the excess" in people's diets, Oliver said.
He said there was a need for "something radical" to slow the rising rates of childhood obesity.
Sugar-sweetened drinks are the biggest source of sugar in children's diets, he said.
Oliver said "doing nothing is inappropriate" and that manufacturers of sugar-sweetened drinks had "hijacked" the Olympics and football matches.
He said there was a need to be "big and bold" adding: "Who is it that's running the country?
"Is it businesses who are profiting from ill health in our children, or is it us?"
Oliver said he had suggested that a three-year sugar tax should be introduced to see how it worked.
"My suggestion to the Government is that we should implement a three-year sugary drink tax of 20% per litre, which is seven pence on a regular can of soda, and that we should absolutely interrogate it and put a sunset clause on it."
He said the tax would then be removed if it had not been shown it was "symbolic" and resulted in a drop-off in sales.
"I'm fully confident that the narrative of benefit to British children would be clear as as bell. But I also realise that if it wasn't, it would be removed."
He said obesity was also putting a huge strain on the NHS, adding: "Being gentle, being polite is not a way to have a progressive obesity strategy.
"We need to be big, bold brave and frankly, act like a parent."
Oliver said having the industry voluntarily reduce sugar was "not working".
During the session, Oliver handed out sugary drinks that he had doctored to make sugar levels much more clear.
He said he had worked out how many teaspoons were in each of the drinks, which included 14 teaspoons of sugar in a bottle of Pepsi and 13 in a bottle of Ribena.
He said he wanted to empower British parents to see what their children were drinking.
"The reason industry do not want you to have that is that the impact is visceral."
Oliver said online was a "minefield" for advertising junk food to children, and was a "bigger problem" than TV.
"It's open territory," he said, adding that online was "not policed".
Setting out his shopping list of demands for action, he said TV adverts for junk food should be banned before 9pm to stop them appearing during major family shows.
He said: "We should not be advertising junk food before 9pm, end of story.
"You can watch Britain's Got Talent and there will be up to 13 advertisement for unhealthy food within that time. Under the circumstances it's inappropriate."
Oliver added that one of the things that upset him was energy drinks in lunchboxes.
"There is no standard for lunchboxes," he said.
Earlier, Oliver accused successive Governments of failing children.
The TV star has been campaigning for a levy of sugary drinks, amassing almost 150,000 signatures of a petition demanding a Commons debate.
He told the committee: "The Government over the last 30 years has done an incredible disservice to children with regards to creating an environment where making a better choice is easy or easier."
Last week, Oliver added his voice to criticism of Health Secretary Jeremy Hunt over his refusal to release a Public Health England review of evidence before the publication of a Government strategy on the issue.
Committee chairman Dr Sarah Wollaston also summonsed Duncan Selbie, chief executive of Public Health England, to explain why he will not defy Mr Hunt and publish the review.
Mr Selbie said there was "no conspiracy" adding that an agreement was reached with Mr Hunt "some time ago".
He said: "I am not in a position to break that agreement" adding "if there is a disconnect between the strategy and what our advice says, I expect to be before you again".