It is all about observation, assessment and developing a greater understanding, before you change the schedule

If you are concerned your child may not be eating enough, keep a food diary over a whole week so that you can see what their total food intake looks like. Biscuits, juice and other snacks may be filling your child up and suppressing their appetite at mealtimes. 
Observe your child’s appetite at different times of the day. They may just be less hungry at certain times. Also remember that their growth and hunger will go in phases. 

Pay attention to how your child behaves around mealtimes to get more of an understanding of what may be affecting their eating. For example, are mealtimes stressful for them? Are they too busy trying to chat and have fun to eat, or are they attention-seeking? If your child is a fussy eater, mealtimes can become very stressful. Step back and look at how much stress occurs at mealtimes. It is entirely normal to feel stressed if your child is not eating enough, as nutrition and growth are clearly very important. However, children can easily start developing associations with food, leading them to avoid or dislike eating particular foods, or worse, food generally. Stress can also suppress digestion and appetite and thus be detrimental to your efforts. Catch your own stressed or worried thoughts – are you worried that you are failing as a parent somehow by your child not eating well? Are you stressed and frustrated by making lots of different meals to tempt your child to eat more? Making mealtimes feel more relaxed and enjoyable for everyone is going to be a key part of this plan, so we will be giving you lots of tips to help with this.