Saturday, October 06, 2007

"Can I Eat A Low-Carb Diet, But Not Eat So Much Fat?"

This is another in my series of posts on low-carb diets. I've been reducing the amount and changing the type of carbohydrate I eat, which by default changes the amount of fat and protein I eat. I'm wondering what the long-term effect of this pattern of eating is.

Sherri (the other Sherri :) commented on a recent post, "I'd be interested in how an Atkins type diet affects health if it just included lean meats."

That's similar to a question I'm often asked: "Can I eat a low-carb diet, but not eat so much fat?" It's not exactly the same as Sherri's question, which just addresses fat in meat. In my case, people are asking if they can do an all-around low-fat version of Atkins.

I think you can make a trade off - eat less carbohydrate and more protein. But I don't think you'll achieve an Atkins' effect without reducing carbohydrate to Atkins' levels. Once you do that, you'll naturally be eating more fat.

In my exploration, I've tried to set aside judgment about low-fat/high-fat or low-carb/high-carb diets. I really don't know yet what macronutrient distribution is best. I like the following quotation. Some readers may recognize its source.1
"Men who have excessive faith in their theories or ideas are not only ill prepared for making discoveries; they also make very poor observations."
- Claude Bernard, An Introduction to the Study of Experimental Medicine, 1865
The following is a hypothetical case of attempting to eat a low-carb diet while moderating fat intake.

Carbohydrate Intake

Say you want to eat an Atkins-type, low-carb diet and you limit your carbohydrate intake to 50 grams a day. If you're eating 1800 calories a day, that amounts to 11% of your caloric intake.

In a recent study comparing low-carb and high-carb diets, the low-carb eaters were consuming 4% of their caloric intake as carbohydrate. So I think 11% is not extreme if low-carb is your goal. Naturally, you could go lower.

That leaves 89% of your calories to come from fat and protein.

Fat Intake

The USDA, American Heart Association, American Diabetes Association, etc. recommend a diet that provides about 30% of calories from fat. (I'm not saying whether I agree with that recommendation. I selected it as an example since many people have in their mind 30% fat as a recommended moderate intake. By contrast, Dr. Ornish's 10%-of-calories-from-fat would be considered a low-fat intake.)

So, say you want to shoot for 30% of your calories to come from fat. If you're eating 1800 calories a day, 540 calories would come from fat. That's about 60 grams of fat a day.

That leaves 59% of your calories to come from protein.

Protein Intake

If you're eating 1800 calories a day, the remaining 1062 calories would have to come from protein. That's about 266 grams of protein a day. (This is only an example.)

What foods provide that level of protein without infringing on your fat and carb limits?

Here are some foods I looked up on
  • White meat chicken breast (140g, 1 cup chopped = 43g protein, 5g fat)
  • White meat turkey breast (140g, 1 cup chopped = 40g protein, 1.5g fat)
  • Beef tenderloin, lean, all visible fat trimmed (85g, 3 oz steak = 24g protein, 7g fat)
  • Canned light tuna in water (165g, 6 oz can = 42g protein, 1g fat)
  • Pork chop, loin, lean, all visible fat trimmed (85g, 3 oz chop = 26g protein, 9g fat)
  • Tofu, lite, firm (85g, 3 oz slice = 5g protein, 1g fat, 1g carb)
  • Non-fat plain yogurt (245g, 8 oz = 14g protein, 0 fat, 19g carb)
Notice that if you want to eat a low-carb diet, but still limit your fat intake, you'll be eating large quantities of lean meats. From the foods above, you might want to eat 6 or 7 cups of chicken or turkey breast daily. Or maybe 5 beef tenderloin steaks for breakfast plus 3 cups of chicken/turkey breast for dinner. If you ate a pound of tofu a day, you'd only get 27g protein towards your 266 gram goal, so you'd need to add another 5 or 6 cans of tuna that day, or another 6 cups of turkey breast.

The pork chop doesn't work well because it's still pretty high in fat for its protein content. The yogurt, as is true with all low- and non-fat milk products, is still too high in carbs for the amount of protein it delivers.

The above example demonstrates, for me, the difficulty of trying to restrict both carbs and fats at the same time. There will need to be a substantially greater amount of lean protein consumed, probably in the form of lean meat, to meet caloric needs. If you eat less protein than what I outlined, then you will, by default, be eating either more than 50g carbohydrate or more than 30% fat.

So, if you choose to eat an Atkins-like low-carb meal plan, you'll likely be eating a high-fat diet.

Which brings me back to a question I've been researching since this summer. What is an optimum carbohydrate, fat, and protein intake for the average person?
1 Gary Taubes, Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control and Disease, Page 1.

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