Take a pair of scissors and cut your food helpings into small pieces. The food will stretch further plus the more you chew the faster your brain tells you are full and you will not over eat.
I fed my husband and myself by cutting "one chicken breast" into small bite size pieces (with a pair of kitchen shears) and then added a cup of fried rice to it and we were full at the end of the meal and satisfied with the portions that we had. At the cost of one boiled chicken breast and 2 cups of rice we were full at the cost of nearly nothing spent for two to eat.
At this time of year, we all do need all the suggestions we can get to keep the "extra pounds" off of our thighs, hips and back ends! Good luck, I personally know that this does work, it saves us money and helps control our weight at the same time.
When my children were small, I decided to cut food into bitesize pieces right away, like in Beef Stroganoff, so I wouldn't have to search for the pieces and then cut, once we started eating. The smaller pieces are distributed easier throughout the dish. You actually end up with more of the meat taste, getting lots of small pieces instead of just a few larger ones. I agree with you, you can make food last longer by using much less.