If you want to lose weight, cutting calories is a good place to start. This does not mean you have to stop eating your favorite foods. It does mean eating less.
“Portion control” means:
See how much you eat
Decide how much to eat
Cut back on portion size
Start by seeing how much you eat. Find out by writing down everything you eat each day. Be sure to write down what you eat and how much. Do this for at least three days. You can use our Food & Activity Tracker or just keep a list on a piece of paper. Many people find that they eat more than they thought!
Look at your list and compare to the serving size guide below. How does your list compare?
Here are some serving size guidelines:
Meat, fish, poultry – 3 oz. (about the size of the palm of your hand)
Cheese – 1 oz. (about the size of your thumb)
Milk, yogurt, fresh vegetables – 1 cup (about the size of a tennis ball)
Bread – one slice
Rice or cooked pasta – 1/3 cup
Potato or corn – 1/2 cup
Dry cereal – 3/4 cup
You may find that your serving sizes are much bigger. If so, it’s time to make a change! Get started by using measuring cups and spoons to serve your food. After a while, you’ll be able to “eyeball” the amount.
Compare your list to the Food Pyramid below. Use it as a guide to how many servings to choose each day from each group. Here are some questions to ask:
Are your portion sizes too large?
Are you eating enough vegetables?
Are you eating too much meat?
Don't feel bad and think you have to lose a lot of weight. You only have to lose 5-10 lbs. to lower your chances for diabetes. If you have diabetes, losing 5-10 lbs. could help you manage it.
from:
http://www.diabetes.org/weightloss-and-exercise/weightloss/portion-size.jsp