Soft policy "nudges" will not on their own solve the obesity problem, a top scientist and politician says.
Incentives and encouragement cannot be relied upon to alter deeply-entrenched lifestyle choices affecting diet, according to Lord Krebs.
Tougher approaches that may involve restrictions on marketing and advertising are needed, he argued.
The Government has set up a behavioural insights team - also known as the "Nudge Unit" - to find ways of discreetly altering human behaviour by persuasion, said Lord Krebs, chairman of the House of Lords Science and Technology Committee and incoming president of the British Science Association.
One example of "nudging" strategy was getting people to re-tax their car by sending them a personalised letter including a photo of the vehicle.
Another was sending text messages instead of letters reminding people to pay court fines.
But evidence suggested that this kind of policy was not strong enough to address major problems such as obesity or unsustainable consumption.
In a speech to be delivered at the British Science Festival at the University of Aberdeen, Lord Krebs said: "Can we tackle these with nudges alone? The short answer is no.
"Last year the House of Lords Science and Technology Committee investigated the topic of behaviour change, with particular focus on two examples, obesity and travel, (how to persuade people to overcome their addiction to cars and switch to more sustainable transport).
"In both cases the evidence was compelling: soft approaches of encouraging behaviour change will not work on their own. In the words of one expert, what is needed is a massive shove rather than a gentle nudge."