Why limit non-natural low carb foods to 300 calories a day?

A reader, Kathryn, wrote the following:

Hello! I have been on the low carb band wagon for about a year now. I had never heard about limiting your intake of non-natural low carb products to 300 calories a day until I found your site. I have searched all over the internet to find more information on this, but the only mentionings I can find are all on your site. Please explain this idea to me. I have been relying on bars and shakes quite a lot lately, being a busy working mom, and I have hit a serious plateau in the weight loss area. Maybe this would help explain my problem!!! Thanks for any advice you can give me!!!

She wrote this while I was in California, and I'm still catching up on things! Anyhow, here goes. (Disclaimer: I am not a doctor or a nutritionist, but I'll share my reasoning with you.) First, I looked at the research, specifically this low carb study out of Harvard which found the following:

A Harvard School of Public Health study may stand dieting wisdom on its head, after low-carbohydrate dieters lost more weight than low-fat dieters despite eating 25,000 extra calories over a 12-week study period.

The findings generated national attention after Penelope Greene, a visiting scholar in the School of Public Health's Nutrition Department, presented her research last week (Oct. 13) at the annual meeting of the North American Association for the Study of Obesity in Fort Lauderdale, Fla.

The study, conducted with Nutrition Department Chair and Frederick Stare Professor of Epidemiology and Nutrition Walter Willett, put three groups of dieters on different regimens. They included a low-fat group, a low-carbohydrate group that ate the same number of calories, and a third group on a similar low-carbohydrate plan that included 300 extra calories a day.

Participants in all three groups lost weight, Greene said, with the low-fat group losing an average of 17 pounds and the low-carbohydrate group that ate the same number of calories losing 23 pounds. The biggest surprise, however, was that the low-carbohydrate dieters eating extra calories lost more than those on the low-fat diet. Participants in that low-carbohydrate group lost an average of 20 pounds...

Subjects were randomly divided into three groups. The low-fat group ate diets that consisted of 55 percent carbohydrate, 30 percent fat, and 15 percent protein. The two low-carbohydrate groups ate diets of 5 percent carbohydrate, 30 percent protein, and 65 percent fat.

The low-fat group and one low-carbohydrate group ate diets limited to 1,500 calories for women and 1,800 calories for men. The second low-carbohydrate group ate diets of 1,800 calories for women and 2,100 calories for men.

Now, if you ate 300 calories more a day, you still lost more weight than the low fat group. Atkins calls this the metabolic advantage. The study's author doesn't go so far:

Though Greene's study didn't allow low-carbohydrate dieters to eat all they wanted, it still provided extra calories that, somehow, didn't translate into extra weight.

While some have said her results defy laws of thermodynamics - since more calories should equal more weight, whatever the calories' source - Greene said the explanation is obviously more mundane.

It has already been shown that it takes more energy to metabolize protein than carbohydrate, Greene said, and that may provide a small part of the answer. Other possibilities are that the body may absorb less of what's eaten in a low-carbohydrate diet, which is high in protein and in fat. Whatever the answer, she said, she's sure the laws of physics still apply.

If you add in pasta or ice cream or cookies to your diet, you are also adding calories, and most of the time you are adding more carbohydrates and more sugar alcohols, etc. While sugar alcohol is absorbed more slowly than regular sugar, it is still absorbed, and how it is absorbed may be a very individual process. In other words, it could mess up this process, whatever it is. (More on that here. And some sugar alcohols like maltitol should be avoided entirely for most people.)

I used to eat all the time because I was hungry! Carbohydrates made me hungry! More carbohydrates, in whatever form (especially Entenmann's that has white flour as an ingredient) really kicks up the old, "I have to eat more" routine. Most low carb food is very high in calories, so if you eat a lot of it and then add more carbohydrates with sugar alcohols, you are eating more calories than the "metabolic advantage" or whatever you call it can handle. Hence, you are likely to not lose weight. Atkins usually does cut calories from the diet because it excludes certain foods, but with low carb versions, these foods are added back in. Atkins is great, but it isn't magic. You have to be sensible.

This isn't based on any scientific study except the above, and it is a huge extrapolation. I'm sure many in the low carb industry might take issue with it -- that is why you won't find it on any other site. But in the Harvard study, they were able to eat 300 calories more and still lose more weight than the low fat dieters. I still call that a win. (Please note though, in the Harvard case, the study participants ate all "real" low carbohydrate food.)

Now, as a long-term regimen, these low carb foods are a lifesaver! They are also a lifesaver in the short term -- in moderation.

I'd love to hear from others regarding this!

To hear more about this on a consistent basis, sign up for the free weekly newsletter!

And don't forget to check out:

Low Carb Kids
Low Carb Recipes
Low Carb Food and Drink Reviews

And Low Carb Shopping Lists (and compare prices) for the Following Chains:

Low Carb Trader Joe's
Low Carb BJ's
Low Carb Costco
Low Carb Stop & Shop
Low Carb Shaw's
Low Carb Market Basket
Low Carb Netrition.com
Surgery: Gastric Bypass & Lap Band

Comments

[Ginger Gower]

I am enjoying your blog. This thing about limiting intake of non-natural low carb foods is something more low carbers need to be aware of. My husband and I figured it a few months ago. When I gave up daily bars and shakes, I began to lose weight again. I do keep bars handy and have a bite or two here and there. I recently read that it is likely that you should only deduct about half the sugar alcohols from your carb count, confirmimg my suspicions that the bars are less benign (for weight loss) than advertised. Also, what is all that stuff in the ingredients lists of these bars and shakes? It doesn't sound like something you should ingest a lot of! But as you say, they can be a lifesaver, and keep you from feeling deprived.
Thanks, and please keep it up!

[Dana]

Sorry for a comment on a three-year-old blog entry, but your remark about "Atkins taking calories out of the diet" just doesn't make any sense. If you take 200 pasta calories out of a daily menu but add in 200 fat calories, you haven't taken out any calories. You've just taken out a food category.

I've been on-again, off-again about my low-carbing this year, something I'd like to seriously clamp down on the next time I go back to a low-carb WOE, but the one thing I did make note of was that I could eat between 2000 and 3000 calories a day, a greater proportion of which was fat, and still lose five pounds in a week. I know this because I kept track in SparkPeople. The U.S. government's Food Pyramid tells me I should be eating 1800 calories a day! But Dr. Atkins predicted this. He also did the math in NDR to demonstrate why calorie theory doesn't make as much sense if you change the composition of your diet.

I think there are several factors in play when low-carb substitute foods are overeaten, and that calories only play a partial role. As you said, sugar alcohols are often the culprit. Another factor is that LC foods often contain wheat gluten and soy, both of which have *weird* effects on some people's metabolisms: soy is goitrogenic, wheat gluten is said to behave like insulin in some people, and both contain phytic acid which inhibits mineral absorption.

So there could be a heck of a lot more going on here than just calories. And I'm personally getting kind of tired of people who cling to calorie dogma like it's a life preserver, when any student of human metabolism knows we metabolize the different macronutrients in different ways and we are not ovens with little flames in our tummies. Laws of thermodynamics, indeed!