Using insights from behavioural sciences to change society's ways should not be regarded as a "get out of jail free" card by governments, says Prof Lord John Krebs.
In an address, Lord Krebs questioned whether persuasion alone is sufficient to alter behaviour on matters such as obesity.
The cross-bench peer spoke at the British Science Festival in Aberdeen.
He argued that some changes may need regulation or taxation.
Lord Krebs also called for better interaction between previously disparate disciplines to help understand motivations and behaviour.
Insights from behavioural sciences are often touted by politicians as a powerful way to try to persuade society to change behaviour.
Lord Krebs used his address to highlight those areas where such an approach has been successful.
However, he also argued that "they are not a 'get out of jail free card' for governments if government wants to avoid tougher approaches like regulation or taxation".
Prof Krebs questioned current scientific priorities. Referring to the recent Mars exploration effort, he said: "There are urgent problems on this planet that will only be dealt with by understanding human behaviour, what motivates people and how to change those motivations in quite radical ways.
"That understanding will only be achieved in my view by bringing together disciplines that haven't necessarily worked together like neuroscience, sociology, behaviour economics and evolutionary biology.
"To be controversial, [this is] a higher priority than spending many billions of dollars putting a vehicle roving around on Mars."
Successes in behavioural change that will be highlighted by Prof Lord Krebs include the reduction in smoking.
In the 1950s, around three quarters of the adult male population were smokers and this has now reduced to less than a quarter.
However, his address will also flag that most successful changes - for example attitudes towards drink-driving or the wearing of seatbelts - have required a mixed line of attack.
He will argue that a combination of approaches - social nudging, regulation, taxation and investment - will be most relevant for those "hard problems", such as tackling obesity and increasing consumption.
His speech will also consider the issue of monitoring the effectiveness of different methodologies and the need for an evidence base to identify the most successful measures.
Prof Lord Krebs is the current president of the British Science Association, which is holding the festival in Aberdeen.