Rule of Three in Label Reading

To find out if a food is a good source of fiber:
It should have at least 3 grams of fiber per serving.
Remember to shoot for at least 25-30 grams of fiber each day.

To find out if a food is a low sugar food:
For every 100 calories, it should have less than or equal to 3 grams of sugar.

Examples:
If the food has 200 calories per serving, it could have up to 6 grams of sugar per serving.
If the food has 300 calories per serving, it could have up to 9 grams of sugar per serving.
If the food has 500 calories per serving, it could have up to 15 grams of sugar per serving.

Also check out the ingredients listing and make sure that "sugar" doesn't fall in the first 3 ingredients. Sugar can also be listed as sucrose, high fructose corn syrup, fructose, honey, etc.

To find out if a food is a low fat food:
For every 100 calories, it should have less than or equal to 3 grams of fat.

Examples:
If the food has 200 calories per serving, it could have up to 6 grams of fat per serving.
If the food has 400 calories per serving, it could have up to 12 grams of fat per serving.

Also, remember that all fats are not created equally. Try to choose foods with monounsaturated fats such as canola oil and olive oil. Try to limit foods with saturated fats (butter) and trans fats (listed in the ingredients as "hydrogenated" oils).