[A you couldn't make it up story. Be easier to ban aspartame and MSG the real causes of Obesity] Formula milk is what keeps babies at the doctors which is why they like it so much.]
Formula milk designed to give babies life-long protection against obesity is being developed by scientists.
The product would be supplemented with leptin, a hormone which has been shown to control hunger.
A commercial launch would be highly controversial because it might encourage mothers to switch from breast feeding, which repeated studies have shown to be best for babies.
Critics said using a hormone to programme children's brains was "scary" and they accused the scientists behind the idea of trying to cash in on fears about obesity.
But scientists at Buckingham University said their studies of leptin showed it could help confront the nation's weight crisis and prevent life illnesses such as heart diseaseand diabetes.
Produced in the body by fat cells, and a natural component of breast milk, leptin turns off hunger in the brain.
Attempts to use it to control eating in adults have failed so far, with patients quickly resisting its appetite- quenching affect. But, given early in life, when the brain is still developing, it could prove much more effective, the scientists said.
When the hormone was fed to pregnant rats, their pups remained lean for life - even when fed a fatladen diet.
The creatures also remained free of type 2 diabetes. Linked to obesity, type 2 diabetes is the most common form of the condition and affects more than a million Britons.
Rats fed the same rich diet without leptin gained weight and developed diabetes, this week's Chemistry & Industry magazine reports.
It is thought that in early life leptin can programme the brain to instruct the body to burn off more energy from food than it would otherwise.
This means that the rats given leptin as pups stored less fat than usual and stayed thin.
The scientists believe that adding the hormone to formula milk could have the same effect on humans - allowing people to remain permanently slim.
Lead Buckingham researcher Michael Cawthorne said: "These babies might be programmed so that they resist the development of obesity and type 2 diabetes. It could be life-long protection.
"The supplemented milks are simply adding back something that was originally present: breast milk contains leptin and formula feeds don't."
It is thought the presence of leptin in breast milk could partly explain why breastfed babies are less likely to become obese in later life than their bottle-fed counterparts.
Pregnant women could be given leptin in supplement form.
Professor Cawthorne said the pet market might also be interested because "fat and diabetic cats and dogs are a major problem".
The scientists, who are seeking funding for human experiments, believe formula products could be on the market within a decade. Prolaterfessor John Speakman, an Aberdeen University obesity expert who contributed to the research, said: "Anything that will influence the obesity epidemic is going to be a major breakthrough.
"Diets have been failing for years and we haven't come up with anything better. So, anything else we can do is going to be of benefit."
Others experts were more cautious. Belinda Phipps, chief executive of the National Childbirth Trust, said leptin was just one of many ingredients in breast milk which made it a healthier choice for mothers and babies.
"Lots of things are missing from formula," she added.
'The difference between breast milk and formula is a bit like comparing a carefully-driven Rolls-Royce with an uninsured old banger."
Dr Ian Campbell, medical director of Weight Concern, said: "The whole principle is questionable.
"It is based on spurious evidence and going for a market of children is both exploiting the current situation and potentially harmful because we don't know the effect it will have.
"Products like this raise false hope and expectation."
Dr Nick Finer, an obesity expert from Addenbrooke's Hospital in Cambridge, said: "The concept that adding something to a food that could permanently alter brain development is exciting but at the same time is so scary that it would mean a wholly new approach about how such treatments can be tested and approved for use."