Sarah Wollaston, a GP before she became the MP for Totnes, branded the document a “plan for inaction”.
Dr Wollaston, who chairs the Commons Health Committee, criticised the plan for failing to tackle the promotion of junk food or force manufacturers to produce healthier alternatives.
She wrote on her blog: “One in four of the most disadvantaged children now leaves primary school not just overweight but obese, more than twice the rate for those from the most advantaged families.
“This plan for inaction will be remembered for its wasted opportunities, delays and spin when it could and should have been the opportunity to show that government is serious about tackling the gap in life expectancy between rich and poor.
“We will all be picking up the tab in the future costs of obesity for the NHS, already more than the police, fire service and judicial system combined, but no one will be paying a heavier price than the individual children facing a lifetime blighted by the consequences.”
The plan, published last week, confirms the Government’s commitment to a tax on sugar in drinks but Dr Wollaston argued it needs to come into force sooner than 2018.
She wrote: “Big industry interests have been given free rein to continue to promote and advertise as they please including those that do so through online marketing masquerading as games or through the powerful use of cartoon characters on junk food aimed at children.”
Celebrity chef Jamie Oliver was among those to criticise the document last week.