Eating slow does not help in weight lost. The communication between your stomach and your brain takes some time. On average it take about 25 to 30 minutes for your brain to get the signal that the stomach is full, if you eat fast then you might eat more food than what you need to before your brain gets the signal.
If you server yourself a healthy portion of food and make sure to not go for seconds then you can eat your food as fast as you want or as slow as you want and you will still get the same results. It's not the speed and amount of time it takes to chew the food that will make you lose or gain weight, it's the total amount of food you consume in each sitting.