Standard Serving Sizes are shown on food products. Nutrients are listed in grams and percentage of the Daily Recommended Intake (DRI). Be careful to read the serving size on the food packet. If the size if 10 potato chips for 50 grams of carbohydrates, and you eat 30 potatoe chips, you will be eating more carbohydrates than you think. Doing this several times a day may lead to an imbalanced nutrient intake or calories in excess of what you want to ingest.
Here is another example: The standard serving size for a bagel is 1 ounce. If you eat a delicatessen "super bagel", you may be ingesting about 600 calories without knowing it. Your health and workout intentions may not be adversely affected. But if you want to ingest those calroies from a protein or fat source for your dietary and workout intentions, the "super bagel" would cramp those eforts.
Some of this information was taken from Winning Sports Nutrition by Linda Houtkooper, PhD, RD, FACSM, Jaclyn Maurer Abbot, PhD, RD and Veronica Mullins, MS, RD, CSCS.
Disclaimer: None of the above information can be taken as a substitute for advice from a medical professional, such as a physician.
My third book, Pocket Guide to Fitness, is available on www.louizapatsis.com, http://www.authorhouse.com, www.bn.com and http://www.amazon.com. If you look up my name on those Web sites, you will find my other books The Boy in a Wheelchair and Life, Work and Play: Poems and Short Stories.