Kashou is a meal replacement product. When to eat depends on whether you feel hungry at that time. It is low in calories and can be eaten at any time. As long as you don't eat it for half a year, it will last for a month or two, and there is basically no side effect, but people with hypoglycemia or anemia should not eat it when they are malnourished.
To put it bluntly, this card is to let you eat less and eat this card instead. Feeling full makes your stomach feel full, but it's just cheating your stomach. There is no essential difference with other meal replacement products.