tag:blogger.com,1999:blog-7721098568390636553.post415895015084423054..comments2023-06-06T07:02:56.002-07:00Comments on The Spark of Reason: Even More DissonanceDavehttp://www.blogger.com/profile/18290594860469294453noreply@blogger.comBlogger9125tag:blogger.com,1999:blog-7721098568390636553.post-2821198782184347732008-08-05T07:47:00.000-07:002008-08-05T07:47:00.000-07:00Dave, I really enjoy reading your blog. I recentl...Dave, I really enjoy reading your blog. I recently stumbled accross this study, and wondered if you had a take on it:<BR/><BR/>http://jama.ama-assn.org/cgi/content/abstract/298/3/309<BR/><BR/>MichaelAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-7721098568390636553.post-51221530971840641162008-07-20T08:47:00.000-07:002008-07-20T08:47:00.000-07:00Hi Steve. I agree that this study has some design ...Hi Steve. I agree that this study has some design flaws. They certainly should have attempted to have greater differentiation between the diets. The other problem is in the reporting. The errors on some of the quantities in Table 2, like Energy Change, are very large. I doubt the data are normally distributed, though. Outliers probably occur mostly on the high side due to those individuals who did not comply with the diet. The "+/-" numbers are standard deviation. If taken as implying normal distribution, we would interpret them to mean that something like 15% of the people on the low-fat and low-carb diets reduced their energy intake by over 2000 kCal, which seems unlikely, unless the authors included people who dropped dead. We need to push the authors to release their raw data, if they haven't already.<BR/><BR/>So I don't think we can draw much conclusion from a lot of the published numbers, because they're almost certainly derived from non-normal data. The mean is a crummy statistic in such cases, the median would have been more useful. Their P-values are also probably polluted by non-normality, and of course P-value answers the wrong scientific question, telling you about your data rather than your hypothesis.<BR/><BR/>It's dangerous to assume that caloric intake is the only variable. Energy output consists of three components: base metabolic rate, physical activity, and thermogenesis. These are clearly variable and change in an effort to maintain energy homeostasis. Consider the following from <A HREF="http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1642696" REL="nofollow">this paper</A>: "In a study on lean and obese ob/ob mice, the lean animals increased their energy intake by approximately 70% on the cafeteria diet. Nevertheless, there was no significant difference in energy deposition, because of the hyperphagia-induced stimulation of energy expenditure in the form of diet-induced thermogenesis (Trayhurn et al. 1982). In this particular experiment the lean animals receiving the cafeteria diet serendipitously had the same energy intake as ob/ob mice consuming the normal diet; in other words, they were ‘pair-fed’ on an energy basis (isocaloric intakes). However, the ob/ob mutants deposited considerably more energy than their lean wild type counterparts, indicating that diet-induced thermogenesis was substantially reduced in the absence of functional leptin (Trayhurn et al. 1982)."<BR/><BR/>There's also evidence that physical activity is modulated by dietary intake, see e.g. <A HREF="http://jn.nutrition.org/cgi/reprint/102/11/1543.pdf" REL="nofollow">this paper</A>. From the standpoint of comprehensive energy regulation, it makes sense that energy output would be regulated along with energy input. Food availability and macronutrient content can vary considerably, so there should be a mechanism for "dumping" extra calories, just like there's one for dumping excess water, salt, etc. Except in disease states, there's no way to excrete this calories in an unused chemical form (e.g. you can't pee out excess fat), so it needs to be lost as energy, either heat or metabolic activity.Davehttps://www.blogger.com/profile/18290594860469294453noreply@blogger.comtag:blogger.com,1999:blog-7721098568390636553.post-20236768824347294662008-07-20T07:30:00.000-07:002008-07-20T07:30:00.000-07:00It's funny how Dr. Ornish always refers to his die...It's funny how Dr. Ornish always refers to his diet program as "plant-based" rather than vegetarian, which it is. That's how I got snookered into buying his "Eat More, Weigh Less" book years ago. Great title! You don't find out until half-way through that it's vegetarian. "Plant-based" is good marketing. Casual observers don't reject it as soon as they might "vegetarian." <BR/><BR/>Ornish makes a valid point that the low-fat group in the study was not particularly low-fat. The researchers guidelines for the low-fat cohort aimed for 30% of calories from fat, 10% of calories from saturated fat. If you look at the baseline diet compositions of all three diet groups, before they ever started the intervention, you see percentage of caloric intake from fat being 31.4 to 32.1%, and saturated fat percentage between 9.7 and 9.9%. So the "low-fat" intervention group didn't really make any significant change from baseline fat intake percentage. The main intervention for the "low-fat" group was to reduce caloric intake, which would reduce fat gram intake as well carb and protein gram intake.<BR/><BR/>[For those who haven't read the study: The low-fat group was also "counseled to consume low-fat grains, vegetables, fruits, and legumes and to limit their consumption of additional fats, sweets, and high-fat snacks."]<BR/><BR/>Ornish is also correct in pointing out the calorie deficit issue. The researchers, in Table 2, report that all three diet groups reduced their daily caloric intake (compared to baseline) by 254 to 591, for 24 months. Just eye-balling the nine numbers presented in Table 2, the average deficit is roughly 450 cals/day. If true, shouldn't they have been losing about 3/4 pound per week, on average, for 104 weeks? They could have avoided that weight loss if they drastically reduced their activity levels, but that's not likely. You can come up with other hypotheses. I agree with Ornish that the most likely explanation is a methodological flaw, and the data points are invalid. Just my gut feeling.<BR/><BR/>I just thought of something. Maybe the reported daily energy deficit refers to entire groups of dieters, not to individual deficits! <BR/><BR/>Sorry to be so long-winded. <BR/><BR/>-SteveAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-7721098568390636553.post-55830196481278958372008-07-19T13:46:00.000-07:002008-07-19T13:46:00.000-07:00Good catch, Joanna! WTG!OYBGood catch, Joanna! WTG!<BR/>OYBOhYeahBabehttps://www.blogger.com/profile/18233544200400642335noreply@blogger.comtag:blogger.com,1999:blog-7721098568390636553.post-1183376142862005722008-07-19T13:39:00.000-07:002008-07-19T13:39:00.000-07:00Hah! While claiming a "physiological impossibility...Hah! While claiming a "physiological impossibility", Ornish manufactured a mathematical impossibility!Davehttps://www.blogger.com/profile/18290594860469294453noreply@blogger.comtag:blogger.com,1999:blog-7721098568390636553.post-31026509231391169052008-07-19T12:19:00.000-07:002008-07-19T12:19:00.000-07:00Dean Ornish: "...those on the "low-fat" diet consu...Dean Ornish: "...those on the "low-fat" diet consumed 200 fewer calories per day—or 10,000 fewer calories per year—than those on the Mediterranean diet..."<BR/><BR/>200 fewer cal/day x 365 days = fewer 73,000 cal in a year, not 10,000, as Ornish stated. By Ornish's argument, those 73,000 fewer cal/yr / 3,500 cal/lb = 20.9 fewer lb/yr!! the low-fatters should have lost over 40 lbs in the two years of the study. No wonder Ornish didn't carry through on this line of reasoning. ;)Unknownhttps://www.blogger.com/profile/08462555203074889481noreply@blogger.comtag:blogger.com,1999:blog-7721098568390636553.post-28197651552197095912008-07-18T08:53:00.000-07:002008-07-18T08:53:00.000-07:00Bravo - I, too hope that we have reached the tippi...Bravo - I, too hope that we have reached the tipping point. It's about time!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-7721098568390636553.post-36901621864801730372008-07-18T06:55:00.000-07:002008-07-18T06:55:00.000-07:00Thank you.The widespread media coverage and ensuin...Thank you.<BR/><BR/>The widespread media coverage and ensuing discussion give me hope that we've hit the "tipping point" on this topic.Davehttps://www.blogger.com/profile/18290594860469294453noreply@blogger.comtag:blogger.com,1999:blog-7721098568390636553.post-49058792894224776252008-07-18T06:42:00.000-07:002008-07-18T06:42:00.000-07:00Great post! It's going to be interesting to see wh...Great post! It's going to be interesting to see where all this discussion leads. I'm looking forward to the next batch of studies that will attempt to discredit this one... and fail to show that high carbohydrates are healthy!<BR/>OYB<BR/>My blog: <A HREF="http://kimorexia.blogspot.com" REL="nofollow">Kimorexia</A><BR/>See <A HREF="http://abcnews.go.com/GMA/OnCall/story?id=4162053&page=1" REL="nofollow">Kimkins on Good Morning America</A>OhYeahBabehttps://www.blogger.com/profile/18233544200400642335noreply@blogger.com