New figures which reveal that obesity levels in Scotland are second only to the US have been described as "horrific".
The Conservative health spokeswoman Mary Scanlon made the claim, adding: "This sends a clear message that we need to start educating people about the dangers of an unhealthy lifestyle, starting with mothers in antenatal classes.
"There needs to be an awareness of the damaging effects created by a poor diet, and insufficient exercise, and incentives to provide balanced, nutritional meals and to encourage an active lifestyle."
Her comments come as an official report described Scotland's "obesity epidemic" as "a major health problem" that must be addressed.
It added the cost of treating obesity-related diseases in Scotland reached an estimated £171m in 2001.
Meanwhile, the Scottish government has set out new nutritional guidelines in a bid to remove sweets and fizzy drinks from schools.
Minister for children Adam Ingram said: "By targeting our youngest citizens, we can make a lasting difference."
Ms Scanlon said that schools have a role to play, but pointed out obesity is apparent in some youngsters not old enough for school.
"There has to be a greater drive in educating those who are responsible for them, and from the earliest possible opportunity," she said.