For me, 'small meals' are basically all my meals. I try to keep my three 'main' meals at 300 - 400 calories and then I add in at least two other meals that are in the 200 - 300 range. Total calories for the day is 1300 - 1600 depending on my activity level. For me, the biggest factor is WHAT I am eating. Right now, with active weight loss actually happening, I am sticking to 40% of my calories from protien, 40% from carbs (mostly veggies/fruit and 1 whole grain serving per day) and 20% from healthy fats. All food is as unprocessed as possible and 95% of it is cooked at home.

I log my food religiously for 5 days (weekdays) and then on the weekends, I aim to eat the same types of meals but I give myself a break from logging. I didn't intend to start this way, but I do feel like it keeps me from feeling like this way of eating is unsustainable. Balance is key for me.

So far, this is working (it's been three weeks). I've got plenty of energy for my workouts (training for a tri) and I'm not starving nor am I thinking about food all day. The best part is that I am steadily losing...something that I haven't been able to do effectively in the past 4 years.

You could try something similiar but just increase your calories by either adding an extra small meal or increasing them all a bit in size until you get to your 1800/day that your trainer recommends.