MPs have demanded that the new public health body for England must be independent of government while saying nudges to encourage better personal health will not work.
The British Medical Association (BMA) has welcomed the Health Select Committee's findings after raising the issues previously and called for a minimum alcohol price to be introduced.
In its report, the Committee concluded that Public Health England (PHE) "must be - and, just as importantly, must be perceived as being - independent of the government."
The MPs also warned of the need for more clarity about who will be in charge in a public health emergency - such as a flu pandemic.
And they insisted that the Secretary of State for Health to be given (under the Health and Social Care Bill) an explicit statutory duty to reduce inequalities in public health as well as to protect the public from dangers to health.
Rt Hon Stephen Dorrell MP, chair of the Health Select Committee, said: "Public Health England (PHE) must be visibly and operationally independent of Ministers. It must demonstrate that it is able to, and regularly does, speak 'truth unto power'.
"Successive governments have spoken of the importance of improving health protection, reducing health inequalities, and raising levels of health and wellbeing across the nation.
"It is an aspiration which we all share, but delivering the aspiration often involves facing uncomfortable questions which it is easier to avoid.
"Those questions are likely to become even more difficult at a time when the NHS faces an unprecedented financial challenge," he added.
The BMA applauded many aspects of the report but was particularly pleased with the call for independence.
Dr Richard Jarvis, co-chair of the Public Health Committee at the BMA, said: "We are very pleased that the Health Select Committee has taken on board the BMA's views.
"We have stressed to the Committee, and to the government, that in order to protect public health, it is essential that Public Health England has genuine independence and the resources to make decisions free from the constraints of central government.
"At a time when the NHS faces unprecedented financial challenges, it is also vital that funding for public health is protected so that doctors and specialists in this area can work towards improving the health of the nation and reducing health inequalities," he added.
Dr Vivienne Nathanson, director of professional activities at the BMA, agreed with the Committee's findings that the government's policy of nudging is unlikely to resolve key public health issues such as obesity and alcohol abuse.
"Responsibility deals that allow the food and alcohol industry to dictate public health policy are not the answer to either the obesity epidemic or the alcohol misuse crisis that the country is facing.
"These issues are complex but the government needs to have the courage to make tough decisions like introducing a minimum price on alcohol and mandatory food labelling," she said.