Interesting article about carb cutting vs calories

janejellyroll wrote: »

"These findings show that all calories are not alike to the body, and that restricting carbohydrates may be a better strategy for long-term weight loss than restricting calories," said study co-author Dr. David Ludwig, co-director of the New Balance Foundation Obesity Prevention Center at Boston Children's Hospital."

I would be cautious.

Also, the article states that the low carbohydrate group exercised more than the other groups. It's not a mystery to figure out how they burned more calories, is it?

For those interested in the study itself, I think this is it: https://www.bmj.com/content/363/bmj.k4583

lemurcat2 wrote: »

Apparently the study was only 20 weeks, which doesn't say much about long-term maintenance.

One comment on the study that I thought raised some good points (from Hana Kahleova):

"...Unfortunately, several methodological issues make the interpretation of the results problematic and the conclusions not well justified.

First of all, the main study objective was to find out if carbohydrate quantity had any significant effect on energy expenditure. In order to answer this question, it is necessary to keep the carbohydrate quality constant across the diets. This may be easily accomplished by standardizing the relative contribution of dietary fiber to total carbohydrates. However, the authors were not only changing carbohydrate quantity, but also carbohydrate quality. More specifically, glycemic index was increasing with the increasing carbohydrate content (GI=30 for low, GI=46 for moderate, and GI=49 for high carbohydrate content). In other words, the higher the carbohydrate quantity, the poorer the carbohydrate quality. This was also mirrored by an increase in serum triglycerides in the high-carbohydrate group, which is another marker of poor carbohydrate quality. Changing carbohydrate quality together with carbohydrate quantity has introduced a serious confounder into the pursuit of the stated research objective."

My note: this is significant because if the carbs in the lower carb diets were more from fiber, calories were not constant.

"Another significant confounding factor was the repeated manipulation of caloric intake when the researchers were adjusting the participants’ energy intake periodically to maintain weight loss within 2 kg of the level achieved before randomization. Even though this study is claiming to have looked explicitly at the metabolic effects of carbohydrates, the changes in caloric intake may have significantly confounded the findings.

Interestingly, the authors admit that “total physical activity, and moderate to vigorous intensity physical activity, were marginally higher in the group assigned to the low carbohydrate diet,” but do not report the exercise in detail. The difference in exercise may well explain, at least partially, the difference in energy expenditure between the diet groups...."

"Finally, the practical implications of the study’s findings are questionable. Long-term adherence to low-carbohydrate diets has been shown to be fairly low (3), plus these diets do not provide any benefits for weight management compared with other diets, particularly in studies with a duration of at least 12 months (4)...."

Note: This was something that struck me too, based on prior studies I've seen.

I'll also note that Ludwig has a big dog in this hunt, so I'm skeptical unless it's shown that the results can be replicated, and over a truly long-term period. The claims are certainly contrary to my own experiences.

Cited references:

3. Dansinger ML, Gleason JA, Griffith JL, Selker HP, Schaefer EJ. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA. 2005 Jan 5;293(1):43–53.
4. Snorgaard O, Poulsen GM, Andersen HK, Astrup A. Systematic review and meta-analysis of dietary carbohydrate restriction in patients with type 2 diabetes. BMJ Open Diabetes Res Care. 2017;5(1):e000354.

janejellyroll wrote: »

lemurcat2 wrote: »

Apparently the study was only 20 weeks, which doesn't say much about long-term maintenance.

One comment on the study that I thought raised some good points (from Hana Kahleova):

"...Unfortunately, several methodological issues make the interpretation of the results problematic and the conclusions not well justified.

First of all, the main study objective was to find out if carbohydrate quantity had any significant effect on energy expenditure. In order to answer this question, it is necessary to keep the carbohydrate quality constant across the diets. This may be easily accomplished by standardizing the relative contribution of dietary fiber to total carbohydrates. However, the authors were not only changing carbohydrate quantity, but also carbohydrate quality. More specifically, glycemic index was increasing with the increasing carbohydrate content (GI=30 for low, GI=46 for moderate, and GI=49 for high carbohydrate content). In other words, the higher the carbohydrate quantity, the poorer the carbohydrate quality. This was also mirrored by an increase in serum triglycerides in the high-carbohydrate group, which is another marker of poor carbohydrate quality. Changing carbohydrate quality together with carbohydrate quantity has introduced a serious confounder into the pursuit of the stated research objective."

My note: this is significant because if the carbs in the lower carb diets were more from fiber, calories were not constant.

"Another significant confounding factor was the repeated manipulation of caloric intake when the researchers were adjusting the participants’ energy intake periodically to maintain weight loss within 2 kg of the level achieved before randomization. Even though this study is claiming to have looked explicitly at the metabolic effects of carbohydrates, the changes in caloric intake may have significantly confounded the findings.

Interestingly, the authors admit that “total physical activity, and moderate to vigorous intensity physical activity, were marginally higher in the group assigned to the low carbohydrate diet,” but do not report the exercise in detail. The difference in exercise may well explain, at least partially, the difference in energy expenditure between the diet groups...."

"Finally, the practical implications of the study’s findings are questionable. Long-term adherence to low-carbohydrate diets has been shown to be fairly low (3), plus these diets do not provide any benefits for weight management compared with other diets, particularly in studies with a duration of at least 12 months (4)...."

Note: This was something that struck me too, based on prior studies I've seen.

I'll also note that Ludwig has a big dog in this hunt, so I'm skeptical unless it's shown that the results can be replicated, and over a truly long-term period. The claims are certainly contrary to my own experiences.

Cited references:

3. Dansinger ML, Gleason JA, Griffith JL, Selker HP, Schaefer EJ. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA. 2005 Jan 5;293(1):43–53.
4. Snorgaard O, Poulsen GM, Andersen HK, Astrup A. Systematic review and meta-analysis of dietary carbohydrate restriction in patients with type 2 diabetes. BMJ Open Diabetes Res Care. 2017;5(1):e000354.

I think it's really irresponsible for Ludwig to specifically spin this as somehow showing low carbohydrate diets are better for keeping weight off long-term. A twenty week study isn't sufficient to conclude that.

Not that I'm surprised . . .

cartersmom06 wrote: »

janejellyroll wrote: »

cartersmom06 wrote: »

I also think in the study the participants were eating mostly processed manufactured carbs and not the good carbs that come from nature like oats and fruit.

Where are you seeing that? I don't see any specific details about the foods provided or limiting foods like oats or fruit in favor of "processed" carbohydrates.

In the study I read it said processed carbs.