Atkins’Diet_DoesitREALLYWork_

1、Atkins Diet: Does it REALLY Work?Dr. Christine Simpson, MD FRCPCGeneral Internal MedicineCHIP Director, EdmontonWho? Dr. Atkins, cardiologistSold 10 million copies of his book, “Diet Revolution”, copyrighted 1973 Other contemporaries:“The Zone”, by Sears“Protein Power”, by EadesWhy?Obesity epidemic

2、began in the late 70sContinual spiral upwards, despite the low-fat dietary messages promotedby the medical profession60% Americans overweight (BMI 25), 30% are obese (BMI 30)What?During the 1970s, new concepts about fat * primary nutritional evil * especially saturated fat of meat & dairyAtkins coun

3、tered this by promising weight loss while eating steak, eggs and butter to our hearts content BECAUSE:* carbs cause obesity and heart diseaseAtkins motto:FAT IS HARMLESS!One follower says of the diet:Atkins allowed his readers to eat “truly luxurious foods without limit,” as he put it, “l(fā)obster with

4、 butter sauce, steak with bearnaise saucebacon cheeseburgers,” but allowed no starches or refined carbohydrates, which means no sugars or anything made from flour. Atkins banned even fruit juices, and permitted only a modicum of vegetables, although the latter were negotiable, as diet progressed. Ga

5、rry TaubesHow? High glycemic index foods (carbs that areabsorbed quickly) promote hyperglycemia.an insulin surge.then hypoglycemiaThis leads to hunger and MORE carbscarvings; hence, increased caloric intakeDuring the insulin surge, sugar is transformed into FAT and muscleThe hypothesis:With a carb-d

6、epleted diet, there are NOinsulin surgesWhen cellular glucose is depleted, fat and muscle metabolism (break-down) beginsThis is the process called “ketosis”, which is identical to that seen in starvationIs there any scientific evidence?Up until 2002, virtually nothingMost “evidence” was anecdotalThe

7、 best scientific evidence requires:* a randomized, controlled trial testing two groups of subjects:a) Atkins diet versusb) high carb diet* Must look for benefits AND harm over time!Two recent scientific studies:July 2002, American Journal of MedicineMay 2003, New England Journal of MedicineFunded by

8、 the National Institute of HealthThe Details:132 people, average weight 286 pounds63 people, average weight 217 poundsLow carb (25-30 g/day, 100-120 Cal)High carb (200-300 g/day, 1200 Cal,25% fat)Followed for ONLY one year!The Results:Low carb:1) in 6 months, lost13 pounds- 2) in 6 months, lost15 po

9、unds;regained 1/3- HDL increased by 18%-Trigs decreased by 28%No diff in LDL or BPHigh carb1) in 6 months, lost4 pounds- 2) in 6 months, lost7 pounds;regained 1/5- HDL increased by 3%Trigs increased by 1%No diff in LDL or BPThe Conclusion:A carb-depleted diet results in greater weight loss in 6 mont

10、hs, and does not cause significant harm to the lipid profile (perhaps even a benefit?).ie. “A healthy, short-term method forweight loss!”?Does that really make sense?Studies are inherently flawed!Flawed in design and interpretationVery low sample size, very short-term40% drop-out rate (same in both

11、groups)What we were NOT told:Carb-eaters caught up with weight loss during the 2nd 6 monthsDiet compositions were actually NOTdrastically different:* 41% (Atkins) fat versus 33%* Dean Ornish says: “they have compared two diets, neither of which is very effective” An even closer look:Most of the weig

12、ht lost in the Atkins dietgroup was due to a decreased total amount of consumed calories!The initial weight loss is water, followed by fat AND muscle; is ketosis dangerous?The lipid profile changes can not be considered secondary to diet compositionsOne more point:Ketosis theory and blood sugar/insu

13、linsurge mechanism:- NOT true when whole grains, legumes,and high-fiber fruits and vegetablesare consumed“Foods as grown, simply prepared!”The REAL scientific conclusion:“l(fā)onger and larger studies are requiredto determine the long-term safety and efficacy of low-carbohydrate, high-protein, high-fat diets.”The debate continues, but the studies to date do NOT prove superiority of an Atkins-style diet over a high COMPLEX carbohydrate diet;Rather, they simply re-emphasize that calorie restrict