Quite a number of nutritional gurus advocate "portion control" as part of a weight loss strategy. While this may make sense on the surface, it does not delve deeply enough into the problem to produce a legitimate solution.
The object of portion control is to control total calorie intake. However, calorie intake can be controlled naturally with two steps, 1) eating the proper foods, and 2) using one's appetitie as a guide.
Consuming too many calories is usually the result of consuming the wrong foods, i.e. calorie-dense junk foods. Fast food/junk food can provide a sizeable amount of calories in a small amount of food volume. So if a person eats McDonald's 3 times a day, they would indeed consume too many calories. But the solution here is not "portion control", but to instead switch to nautral foods that are much less energy-dense: lean meat, fruits, vegetables, etc.
Second, if a person eats natural foods their appetite is a quite suitable guide to the correct calorie intake (given a minimum level of physical activity). After all, appetities successfully guided hunter-gatherers through millions of years of evolution. And this is not because hunter-gatherers lacked food, and hence went hungry. This research shows that food shortages were quite rare among hunter-gatherer tribes.
I never practice portion control - I eat until I'm full. Some days I'm hungrier than others, some days I eat more, some days I eat less. This is all a natural process as my body signals its needs and tries to get the needed calories and macronutrients. I'll take my chances with this method versus any type of artificial restriction.