Is it normal for a toddler to lose his or her appetite?
Frequent complaints some mothers  have when their toddlers  don’t eat as much as they used to.
According to  Claire Mccarthy ; a paediatrician she explained that it is very normal. Here’s why:
First, toddlers are busy people. Eating can seem low-priority to a kid who has a block tower to build, a doll to dress, and serious scribbling to do. Toddlers also become more discerning—okay, picky—about their food as their independence grows and they start to express their own likes and dislikes. They don’t like to be told what to do, eating included.
There’s biology involved, too. Children’s rate of growth is very rapid for about their first 12 months of life, and then it slows a little. It makes sense that they’d need less food to fuel them after that point.
So don’t push your  son  or  daughter to eat. It’s better if you let  them listen to their own hunger cues; this can help prevent obesity later on. Offer them healthy choices at various times of day (they won’t starve!).
Very rarely, a loss of appetite can be more of a problem. Call your doctor if you observe they’re:
losing weight
complains of a stomach ache or other pains
is vomiting or has diarrhea or blood in her stools
has fever, cough , or other signs of illness.
Otherwise allow them follow their  own pattern of growth
(Source:Claire McCarthy, M.D., director of pediatrics at the Martha Eliot Health Center.)