Hundreds of obese Falkirk children may be among more than 1,500 in Forth Valley, Tayside and Fife referred to specialists over the last three years.
The claim is made by the Scottish Conservatives, who say figures they have uncovered show thousands of adults - 2,406 in Forth Valley - have the same problem.
A spokesperson said: “Scotland’s obesity epidemic shows no signs of abating and some health boards now provide gym memberships in order to improve activity levels”.
The Scottish Government’s official consultation on obesity closed at the end of January.
Mid-Scotland and Fife list MSP Liz Smith said: “These figures show that thousands of people across Tayside, Fife and Forth Valley are struggling to keep their weight under control and are now at the point where doctors are stepping in to provide support.
“The offer of free gym passes is a good one and its vital that people who are struggling with weight issues are given support to lead healthier lifestyles.
“However, exercise is only one side of the coin and more focus must be taken on helping people make healthier eating choices.
“The financial burden of supporting those with weight-related health issues is set to increase and its vital that the NHS invests in preventative healthcare solutions”.
She added: “However, it’s also important that parents take responsibility and ensure that they provide their children with the healthiest possible environment to grow up in.
“Obesity will be one of the great public health challenges of our time and it’s important that the Scottish Government makes the right decisions now to lay the groundwork for better future health.”