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Is there a parasympathetic response to caloric restriction
Low Carbohydrate Diet
low carb low down
Re: Calorie intake with Low Carb group
Calorie intake with Low Carb group
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MARTIN CAICOYA, MD, MPH, PhD Hospital Monte Naranco
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mcaicoya{at}hmn.es MARTIN CAICOYA
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Knowing that this response is a late response, I should like to pose a question to the authors. In both regimes the blood pressure and the heart rate diminishes. Can it be a parasympathetic effect?. If so, can it explain why the caloric restriction has no effect in the long term as it is compensated by a decreased energy expenditure?. Thank you Martín Caicoya Conflict of Interest:None declared |
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Dean Ornish, MD University of California at San Francisco
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Dean.Ornish{at}pmri.org Dean Ornish
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Although purporting to show that a low-carbohydrate ‘Atkins’ diet is more beneficial than a conventional "low-fat" AHA/NCEP diet, these two studies really documented that neither diet is very effective in lowering weight or LDL-cholesterol (LDL-C). In both studies, LDL-C did not change significantly and there were no significant differences in weight after one year (only about 3% weight loss), which was also seen in an earlier study. The conventional AHA/NCEP ‘low-fat’ diet is not very low in fat or cholesterol and reduces LDL-C by only 5% in most patients, if at all. Since this diet is often high in refined carbohydrates (which increase triglycerides), an Atkins diet often shows greater reductions in triglycerides, especially when taking fish oil. In contrast, a diet containing 10% of calories from fat with little saturated fat and dietary cholesterol decreased LDL C by an average of 40% after one year in patients not taking lipid-lowering drugs. Also, they lost 24 pounds during the first year and kept off more than one-half of that weight five years later, whereas randomized control group patients on an AHA/NCEP diet did not lose weight. Exercise levels were not significantly different. It is important to distinguish between risk factors such as lipoproteins from direct measures of disease. Studies using serial coronary arteriography to assess patients consuming an AHA/NCEP diet revealed that the majority showed worsening of coronary atherosclerosis.4 In contrast, patients who followed a 10% fat unrefined foods diet demonstrated significant regression of coronary atherosclerosis after one year as measured by quantitative coronary arteriography and even more regression after five years.5 In addition, they had 2.5 times fewer cardiac events than randomized control group patients following an AHA/NCEP diet, who showed more progression of atherosclerosis after five years than after one year. There was a direct correlation between the intake of dietary cholesterol and total fat and changes in coronary atherosclerosis. Similar results were found by others. Also, 99% of experimental group patients stopped or reversed the progression of CHD as measured by cardiac PET scans. Only one peer-reviewed study examined the effects of an Atkins diet on cardiovascular disease rather than only risk factors. Myocardial perfusion improved on a very low-fat whole foods diet but worsened on an Atkins diet. The burden of proof is on advocates of low carbohydrate diets to show otherwise in randomized controlled trials using direct measures of cardiovascular disease, not just risk factors or epidemiological studies, especially given data linking diets high in saturated fat and red meat with the incidence of heart disease, cancer, osteoporosis, and renal disease. The harmful effects of a high fat diet may be mediated through other mechanisms than traditional risk factors. For example, dietary fat intake increases plasma levels of factor VII coagulant activity (VIIc).4 Indeed, one man in the low-carbohydrate group developed angina and CAD near the end of the study even though his risk factors had improved,1 and another died of ischemic cardiomyopathy.2 We need to move beyond simplistic notions that anything which raises HDL-C is beneficial and anything that lowers HDL-C is harmful. Reducing dietary fat and cholesterol may cause a decrease in HDL-C because there is less need for it. There are no data showing that the physiologic reduction of HDL-C levels with a low fat diet is detrimental. The debate should not be ‘low carbohydrate’ versus ‘low fat.’ Patients have a spectrum of dietary choices. To the degree they reduce their intake of refined carbohydrates and excessive fats and increase their intake of unrefined carbohydrates (fruits, vegetables, whole grains, legumes) and sufficient omega 3 fatty acids, they may feel better, lose weight, and gain health. Dean Ornish, M.D. Preventive Medicine Research Institute Clinical Professor of Medicine, University of California, San Francisco Yancy WS, Olsen MK, Guyton JR, Bakst RP, Westman EC. A low- carbohydrate, ketogenic diet versus a low-fat diet to treat obesity and hyperlipidemia. Ann Intern Med. 2004; 140:769-777. Stern L, Nayyar I, Seshadri P, Chicano KL, Daily DA, McGrory JM, et al. The effects of low-carbohydrate versus conventional weight loss diets in severely obese adults: one-year follow-up of a randomized trial. Ann Intern Med. 2004; 140:778-785. Foster GD, Wyatt HR, Hill JO, McGuckin BG, Brill C, Mohammed BS, et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med. 2003; 348:2082-90. Ornish D. Concise Review: Intensive lifestyle changes in the management of coronary heart disease. In: Harrison s Principles of Internal Medicine (online), edited by Eugene Braunwald et al., 1999, and In: Braunwald E. Harrison s Advances in Cardiology. New York: McGraw Hill, 2002. Ornish D, Scherwitz L, Billings J, et al. Intensive lifestyle changes for reversal of coronary heart disease Five-year follow-up of the Lifestyle Heart Trial. JAMA. 1998;280:2001-2007. Ornish D. Was Dr. Atkins right? Journal of the American Dietetic Association. 2004;104(4):537-542. Esselstyn CB Jr. Updating a 12-year experience with arrest and reversal therapy for coronary heart disease. Am J Cardiol. 1999 Aug 1;84(3):339-41, A8. Gould KL, Ornish D, Scherwitz L, et al. Changes in myocardial perfusion abnormalities by positron emission tomography after long-term, intense risk factor modification. JAMA. 1995;274:894-901. Fleming R, Boyd LB. The effect of high-protein diets on coronary blood flow. Angiology. 2000;51: 817-826. Connor WE, Connor SL. The case for a low-fat, high-carbohydrate diet. N Engl J Med. 1997;337(8):562-563. Conflict of Interest:None declared |
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Maryam Fotouhinia, R.D. M.Sc Medisys Health Group
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maryam.fotouhinia{at}medisys.ca Maryam Fotouhinia
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The low carb diet may be more effective in rapid weight loss, however the improved triglycerides levels and the weight loss may be temporarily. In this study, subjects in low carb group were given chromium picolinate which is compound that interacts with insulin and helps maintain regular blood sugar levels and it is commonly used for diabetic patients. Chromium which serves as an appetite suppressant was used only in the low carb group. Would the result have been as significant without such supplements? Also as seen in my own practice as a dietitian, the low carb diets can not be maintained for extended periods of time. Generally the cravings for sweets and simple carbs are increased once the chromium is stoped and the allowed carbohydrate intake level is increased. Therefore the weight loss is temporarily and the triglycerides are also increased again depending on the level simple carbohydrate intake. And finally, the increased HDL level, could it simply be due to higher cholesterol intake? Could the HDL be simply used to circulate the extra load of dietary cholesterol? To determine the fate of low carb diets, all these and many other factors, some mentioned here some elsewhere, need to be evaluated in a different study and preferably one that is not funded by the Atkins foundation. |
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Michele E McAlister, M.S.,R.D.L.D., M.S. in Food & Nutrition Endocrinology Associates
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michelem{at}endo.wtxcoxmail.com Michele E McAlister, M.S.,R.D.L.D.
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I just have to wonder if the improvement in the triglycerides and HDL were as a result of the nutritional supplementation and less by the actual diet. We currently treat our patients with high triglycerides with omega 3 fish oil supplements. To really assess whether the effects were from the low carb diet or the nutritional supplementation, the low fat diet should be supplemented with the same supplements. I also would like to know how the patients were monitored as far as if they were truly following the low fat diet. In working with patients for over 14 years I find that many people do not know how to translate the recommendations for 30% fat in to real people terms. They often mistakenly think they are to limit fat grams to 30 grams. Were they instructed to use more MUFA? I also would like to know if the patients were instructed to limit white flour products because that would also affect the triglyceride levels. My last question is regarding to the method of analyzing fat loss versus muscle loss. How was this determined? My biggest concern is when people lose weight too fast they seem to lose more muscle mass which in turn slows the metabolism dowm. Your consideration in this regard is certainly appreciated. Conflict of Interest:None declared |
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thomas Mango, MD SUNY Stonybrook
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fracture{at}aol.com thomas Mango
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Having lost 90 lbs using a low carbohydrate diet while counting calories as well, I noticed that my calorie count went down substantially while on a low carb diet. In fact without realizing it my calorie intake dropped significanly more than 500 to 1000 cals. Could the weight loss effect simply be from this effect combined with a satiety level obtained by eating more fat. PS It would be helpful if you qualified for the scientific community if the 20 gram carb restriction included fiber or if fiber was subtracted. I ask this because two cups of salad vegetables and one cup of acceptable vegetable is well under 20 grams if you subtract fiber. Conflict of Interest:None declared |
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