I always manage to break food scales because I move fairly often and they tend to get shaken and not function properly after a bumpy car journey. Because of this I have a pet hate for recipes that define the quantity of ingredients by weight.
I try to follow portion size advice like a portion of cheese should be the size of a matchbox and a portion of protein the size of a deck of cards. Here's a pretty interesting link http://www.prlog.org/10376002-dallas...be-simple.html
It states that:
"A fist or cupped hand = 1 cup
1 serving = 1/2 cup cereal, cooked pasta, or rice
OR 1 cup of raw, leafy green vegetables
OR 1/2 cup of chopped fruits or vegetables
A thumb = 1 ounce of cheese
Handful = 1-2 ounces of snack food
Remember, 1 handful = 1 ounce of nuts and small candies. For chips and pretzels, 2 handfuls = 1 ounce
Palm = 3 ounces of meat
Thumb Tip = 1 teaspoon
Keep high fat foods like mayonnaise to a minimum by measuring the serving with your thumb. One teaspoon is equal to the end of your thumb, from the knuckle up. Three teaspoons equals one tablespoon.
1 tennis ball = 1 serving of fruit
Healthy diets should include 2-4 servings of fruit each day. "
So I'd say it's not necessary to own a food scale to lose weight if you are aware of portion control. If I find out what I'm doing is not working, then I'd buy a food scale (again...) but for now I don't see a need.