Food should be given to children when they're hungry
Giving food to children just because they're crying is not a great idea. Offering food seems like an easy solution because often it will pacify a crying child, but using food for reasons other than hunger is a habit that's hard to break. Many adults aren't able to break the habit. More than half of Australian adults are overweight and this is sure to be a contributor.
Usually we know when children are hungry. We know whether or not they have had breakfast, what percentage of their bottle they drank, how long since they last ate and how filling their last meal or snack would have been. We also usually know why they're crying. When you know children well you can differentiate between their behaviours. We usually know their typical sleep patterns. I have a rule that I use with babies. If they're under 6 months they will be tired within 2 hours of waking and if they're between 8 and 12 months they will usually need three hours awake between daytime sleeps. If they're over 12 months they will probably be transitioning to one sleep during the day.
Other reasons that children cry could be having a wet or soiled nappy, feeling scared or insecure, craving attention or physical contact (maybe they just want a cuddle with you), teething or feeling other types of physical discomfort, or feeling bored. The best way to deal with crying is to address the child's specific need in the most appropriate way.
If children are hungry offer them healthy, satisfying food and let them have as much as they want. Usually children instinctively know to stop when they are full. If food is low in sugar and salt children won't be tempted to eat more than is right for them. Remember children's eating patterns will change over time dependent on whether they are teething or experiencing faster or slower periods of growth.