Ask an Expert: Protein vs. carbohydrates

Q: What role do proteins and carbohydrates play in the diet?  Should I be avoiding carbohydrates altogether if I’m trying to lose weight?

Answer from Kimra Hawk, R.D., L.D., outpatient dietitian, and Terese Scollard, R.D., L.D., M.B.A., regional clinical nutrition manager: 

Carbohydrates and proteins are both vital for good health. Each of these nutrients plays a unique role in building and maintaining a healthy body, so any diet that deprives you of one or the other over an extended period of time can put your health at risk.

Let’s begin by looking at protein. Protein is the raw material your body uses to make and maintain healthy muscles, bones, skin and hair. Without an ongoing supply of this nutrient you would gradually lose muscle mass, become weak and forfeit your ability to fight disease and infection. 

The average adult needs about 60 to 80 grams of protein each day. That may sound like a lot, but not when you consider threes ounces of meat (about the size of a deck of cards) provides 21 grams of protein. The best sources of protein include meat, fish, eggs, milk, cheese and legumes (beans, peanuts, peas and soybean-derived foods).  Some vegetables and grains contain protein, though not of the same quality as the primary sources I mentioned.

Now let’s look at carbohydrates. Your brain, heart and kidneys depend on carbohydrates for energy to function properly. If your diet does not include enough carbohydrates your body will take extreme measures to get the energy it needs; it will feed on carbohydrates stored in muscles and attempt to chemically break down the proteins you eat until those proteins look and act like carbohydrates. Such reactions can produce muscle loss and put extra strain on the kidneys as the body works to dispose of unused protein by-products. 

Many people have the false impression that carbohydrates are fattening, perhaps because carbohydrates are often associated with those low-fat cookies, crackers and chips that can add pounds if not eaten in moderation. Low-fat snacks are usually high in calories; it is those calories – not carbohydrates themselves – that cause weight gain when such snacks are consumed often or in large portions.

Many low-calorie, carbohydrate-rich foods are available for those who wish to lose weight or maintain a healthy, balanced diet. As a general guideline, adults should get about 40 percent to 60 percent of their daily calories from carbohydrates. Good choices include minimally processed products such as oatmeal, brown rice and whole-grain bread. Look for the words "whole grain" among the primary ingredients on bread packages. Breads that do not carry this label are highly processed and do not provide your body with the same quality of nutrition.

When it comes to weight loss, your body cannot tell the difference between calories consumed as carbohydrates and calories consumed as proteins. If you eat fewer calories than you burn through your daily activities, you will lose weight regardless of the type of foods you eat. Following a weight loss plan that promotes balanced nutrition and a variety of food choices will allow you to stay healthy and energized as you diet and prevent you from becoming bored and giving up before your reach your goal.

September 2003