February 13, 2005

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What Are Good Carbs?

We're hearing a lot these days about "good carbs," and there's no question that some carbohydrate foods are better than others. But what is a "good carb," really?

To me, there are two factors that determine whether a carb is good or bad. One is the blood sugar impact - does the food have a high or a low glycemic index? Will it spike your blood sugar, leading to a big insulin release, with its subsequent blood sugar crash with its familiar symptoms - irritability, fatigue, and gnawing hunger? Or will it be absorbed fairly slowly?

For about a decade, from the mid-'80s to the mid-'90s, we were told that "simple carbs are bad, complex carbs are good." There was, however, a lot of confusion as to what "simple" and "complex" carbs were. I've often seen these terms misused; a lot of writers use "simple carbs" to mean refined, process carbs, and "complex carbs" to mean unrefined, unprocessed carbs. That's actually incorrect. Simple carbohydrates are sugars, whether found in a can of Coke or in an apple. Complex carbohydrates are starches, whether found in a slice of squishy white bread, or in a bowl of homemade bean soup.

The reason for the push toward complex carbohydrates was the belief that starches were digested and absorbed more slowly than sugars, and therefore would have a more modest impact on blood sugar levels. This turns out to be simplistic. There are simple carb foods - most fruit, for example - that have a modest blood sugar impact, while there are starchy foods like potatoes that have a whopping high blood sugar impact.

Many things affect glycemic index. Fiber lowers glycemic index by physically slowing the absorption of the digestible carbohydrate. It sits like a sponge in your gut, time-releasing the carbohydrate into your system. For this reason, most fruit has a low glycemic index, while the index for juices is higher. Texture makes a difference - an apple will have a lower glycemic index than unsweetened applesauce, and dense, flat pita bread has a lower glycemic index than loaf bread. Coarsely ground flour has a higher glycemic index than unground grains, but a lower glycemic index than finely milled flour.

Cooking methods can make a difference - potatoes always have a very high glycemic index, but boiling them lowers it a bit, while baking them raises it. Processing makes a difference - simple steamed brown rice has a moderate glycemic index, while those styrofoam-y rice cakes, made from puffed brown rice, might as well be pure glucose. And eating low glycemic index foods like proteins and fats along with higher glycemic index foods will result in a blood sugar impact between the two. (This means that, contrary to popular food-combining diets, carbohydrate-rich foods will be easier on your blood sugar if eaten with a meal that includes protein and fat.)

The second factor we need to concern ourselves with is the nutrient density of the carbohydrate food - how many vitamins and minerals will it add to your day? How many antioxidants? Does it come with a substantial whack of protein, too? Maybe some healthy fats? Good carbohydrates offer plenty of nutritional value along with a modest blood sugar impact.

The very best carbohydrate foods are vegetables. I trust this doesn't come as a big surprise! For many of us, there would be no problem with eating 50 - 60 grams of carbohydrate per day, or even more - so long as we ate it all in the form of lettuce, spinach, broccoli, cauliflower, mushrooms, cabbage, sprouts, etc, etc, etc. I eat unlimited quantities of these foods, and most of you should be able to as well - it's hard to overeat on leaves!

Most fruit has a low glycemic index, and of course it contributes vitamins, minerals, and antioxidants to our diet. Happily, many of the fruits highest in antioxidants are among those lowest in sugar - berries are little antioxidant powerhouses, and cantaloupe is wonderful as well. But there's no question that an apple or an orange, while higher in carbohydrate than, say, strawberries, falls into the "good carbs" category.

We don't tend to think of milk as a carb food, but it actually has 50% more carbohydrate than protein - 12 grams of carbohydrate, 8 grams of protein in a cup. That carbohydrate is in the form of lactose, aka milk sugar. If you're lactose intolerant, milk won't be a good carb for you, of course. But if you can consume lactose without problems, milk has a low glycemic index, and certainly makes a strong nutritional contribution to your diet - among other things, getting enough calcium seems to encourage healthy body weight, and of course we know about protein. Depending on the milk you get, the fat in it may also be a good source of conjugated linoleic acid or CLA, a very healthy fat thought to prevent cancer and help burn fat.

(If you are lactose intolerant, I'm afraid the "Lactaid" milk has a considerably higher glycemic index than regular milk. You might try Carb Countdown carb-reduced milk instead, but then, of course, it won't be a carbohydrate food.)

Vegetables, fruits, and milk all have something else in common: They're high in water. This means that they're less concentrated than whole grains and beans. A six-and-a-half inch whole wheat pita has about 31 grams of usable carb. A half a cup of hummus (chick pea dip) has about 20 grams of usable carb. A whole head of romaine lettuce has only about 17 grams of usable carb, 1 cup of milk, as mentioned, has 12 grams, and a navel orange has about 14 grams of usable carb. Clearly, the more concentrated your sources of carbohydrate, the smaller your portions will need to be. Personally, I'd usually rather have a great big huge pile of salad than one slice of bread, but there are moments when one slice of 100% whole grain rye toast is just exactly what I want. So let's move on to the more concentrated carb foods.

Legumes - dried beans, split peas, lentils, chick peas, and the like - all have a low glycemic index and substantial nutritional value. If you like them, a cup of split pea, lentil, or bean soup would be a good carb - just watch your portions.

While potatoes have a high glycemic index, sweet potatoes are somewhat lower, and offer far more nutritional value. Better yet, true yams have an even lower impact. Yes, these are two different foods, though the terms have often been used interchangeably. Please, no sweet potatoes or yams with Karo Syrup or marshmallows! But a small baked sweet potato or yam with a little butter, salt, and pepper would fall into the "good carbs" catagory.

How about whole grains? They're better than refined grains, there's no question about it; they have more fiber (some is more than none!) and a wider variety of vitamins and minerals. Still, to my mind, they're the least valuable and most problematic of the bunch. They are very dense in carbohydrate, so it's easy to overshoot your limit. They're also the source of a lot of allergies and food sensitivities.

I remain convinced that grains are completely inessential for human nutrition. They, along with legumes, have only been a significant part of the human diet for the roughly 10,000 years since humankind invented farming, and were virtually non-existent in hunter-gatherer diets people ate for 2 million years. Doesn't sound terribly essential to me.

However, I'm well-aware that grains are the carbohydrate that many people miss the most. I'm not entirely immune to their allure myself - at this moment I have low carb tortillas, low carb bread, and Finn Crisp rye crackers in the house. And I've been known to indulge in a slice of whole grain rye toast from time to time. So it's vitally important that we sort out the better from the worse, where whole grains are concerned.

Since processing increases blood sugar impact, virtually all cold cereals have a high glycemic index, even whole grain, unsweetened varieties like Cheerios. They're a poor choice. (The exception is the spaghetti-shaped bran cereals like All-Bran, which have a low blood sugar impact - all that fiber!) As mentioned, whole wheat pita will have a lower glycemic index than whole wheat loaf bread. Whole wheat pasta and brown rice have moderate glycemic indices, but they're both higher than barley, which is the lowest-impact whole grain there is. Dense, coarse-grained bread has a lower impact than softer breads. Whole grain rye bread - a favorite of mine - has a lower impact that whole wheat bread.

Many people think of oatmeal as the best of all possible grains. It's true that old fashioned rolled oats have a moderate glycemic index, but "steel cut" oats, traditional in Scotland, have a lower impact. They also take longer to cook! If you want to try them, but are in a hurry in the morning, try this: Scald a Thermos with boiling water, to pre-heat it. Then combine steel cut oats and boiling water in the Thermos, using the proportions listed on the label. Cover, and let sit overnight. You'll have cooked oatmeal when you get up. Eat some protein with it, will you? You don't want to be hungry by 10:00.

Quick cooking oats have a higher glycemic index than rolled oats - more processing, remember? - and instant oatmeal is the worst of all. Further, it nearly always has sugar added, and sometimes hydrogenated vegetable oil. These cannot be considered "good carbs."

Another grain I give in to at least once or twice every summer is sweet corn. It has a moderate impact, and comes in conveniently limited portions!

There are low glycemic index foods that don't have much nutritional value - for instance, Snickers bars have a fairly low impact for a candy bar; so do Peanut M&Ms. Both fall short in the vitamins-and-minerals department. Conversely, those highly advertised "diet shakes" have a bunch of vitamins added, but the carbs in them are of the cheapest and most damaging kind.

Along with blood sugar impact and nutrient density, it's important to keep an eye on the actual number of grams of carbohydrate in a portion. Your total carb intake still matters. For example, the South Beach Diet allows 1/2 cup of oatmeal one day, then two days later you get 1 slice of whole grain toast - hardly an orgy of whole grains. I worry that all this talk about "good carbohydrates" will lead people to believe that all they need to do is switch from white bread to whole wheat, and white rice to brown, and everything will be fine. If you're carbohydrate intolerant, this is unlikely to work. Before I went low carb, I hadn't bought white bread or white rice in almost twenty years - it was a steady diet of whole grains that got me up to 190 pounds at 5'2", and drove my nagging, constant hunger.

I can't tell you how many grams of carbohydrate you can eat each day and still lose weight. That's something you'll have to work out for yourself, through trial and error. I know that I have to stay under 60 grams of non-fiber carbs per day, regardless of how good the source, or my weight starts to creep up - but that's me. It's entirely possible that your limit is 100 grams per day - or that it's 20. Only experimentation can tell you that. Pay attention to your body, and remember that if you're hungry again within 90 minutes of eating any particular carb food, it's probably not for you.

For reference purposes, here's a link to the most extensive list of glycemic indices on the 'net: http://www.mendosa.com/gilists.htm Also includes glycemic load, which is wonderful. Keep in mind if a particular food you're interested in isn't here, a quick google on "glycemic index" will turn up other lists.

Posted by HoldTheToast at February 13, 2005 12:55 PM