Comfort eaters who claim to never feel full may be telling the truth.

Junk food eaters who eat burgers and milkshakes may never feel full because fatty palmitic acids found in beef and dairy products reverses the brain's alarm system which tells people that they feel full.

This may mean that junk food eaters brains tell them to keep eating rather than stop when the body has eaten enough. Of cause there is also the issue that burgers from McDonalds and Burger King et al never really feel like a good meal as they are low in complex carbs and fibre - the two elements in food that normally fill the stomach and make the eater feel like they have had a hearty meal.