Presentation on theme: "Popular Weight Loss Diets: What’s The Evidence?"— Presentation transcript:
1 Popular Weight Loss Diets: What’s The Evidence? Low Carbohydrate DietsCJ Segal-Isaacson, EdD, RDHigh Protein DietsManny Noakes, PhDLow Fat DietsKeith Ayoob, EdD, RDApplication for CME credit has been filed with the American Academy of Family Physicians. Determination of credit is pending The AAFP is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor Continuing Medical Education.
2 Focus of Each Talk: Define Diet Present The Evidence for It’s Weight Loss EffectsPresent The Evidence for Cardiovascular and Insulin Sensitivity EffectsConclusions
3 Low Carbohydrate Weight Loss Diets CJ Segal-Isaacson, EdD RDAssistant ProfessorDivision of Nutrition and Health BehaviorDepartment of Epidemiology and Population HealthAlbert Einstein College of Medicine, Yeshiva University
4 Cathy... On Low Carbohydrate Diets by Cathy Guisewite Over the past couple of years there has been a revival in public interest about low carbohydrate diets...
5 Different Strokes For Different Folks One size does not fit all with weight loss diets --- we need a variety of approaches to combat the obesity epidemic.It is possible that lower carbohydrate diets may be more effective for people with Metabolic Syndrome.1-2Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. May ; 348 (21):Eckel RH, Drazin B. J. Investigative Med. 51:Suppl ; S383.
6 Popular Low Carbohydrate Diets The Dr. Atkins Diet (Has four levels):Induction (<20 g of carbs)Ongoing Weight Loss (Typically grams carbs)Premaintenance (Typically grams carbs)Maintenance (Typically grams carbs)Carbohydrate Addicts’ DietProtein PowerCyclic KetogenicThe Zone Diet ( )Neanderthin
7 2001 International Low Carbohydrate Weight Loss Survey* Internet-based questionnaire.Data collected June-July 2001.6,088 low carbohydrate dieters responded.*Segal-Isaacson CJ, Segal-Isaacson AE, Wylie-Rosett, J. The Journalof The American Dietetic Association : S45.
8 Who Responded To The Survey? Questionnaire Was Web-based, With Online Consent FormSAMPLE SIZE: 6,088 “Low Carbers” Responded, June-July 2001GENDER: 75.4% Women % MenRACE: 90.5% White 3.5% Hispanic % Black 3.3% OtherMAIN GEOGRAPHIC LOCATIONS: 87.5% USA 0.5% CanadaHIGHEST EDUCATIONAL DEGREE ATTAINED:0.5% Elementary School29.4% High School21.3% Associates Degree31.5% Bachelors Degree13.0% Masters Degree4.4% Doctoral Degree
9 The Three Most Common Low Carb Diets 2001 Low Carbohydrate Weight Loss Diet Survey)* N= 5177 *Segal-Isaacson CJ, Segal-Isaacson AE, Wylie-Rosett, J. The Journal of The American Dietetic Association : S45.
10 Typical Macronutrient Profile of Low Carbohydrate Diets Nutrient Percentage of CaloriesCarbohydrate: 5-25%Protein: %Fat: %Alcohol: <5% (metabolized mostly as fat)Macronutrient percentages may distort what actually occurs in low carbohydrate dieting.Due to increased satiety, less food may be eaten. Carbohydrate intake is reduced while fat and protein intake may only moderately increase. Calories are often substantially reduced.
11 Typical Low Carbohydrate Dinner FoodPortion SizeCaloriesCarbs (g)Fat (g)Protein (g)Roast Chicken1/4 Chicken3061931Green Beans with Sunflower Seeds and Olive Oil3/4 Cup10293Green Salad with Italian Dressing2 Cups with1 Tablespoons7442Diet Gelatin with Whipped Cream1 Cup with1 Tablespoon706TOTALS :550153839
13 Micronutrient IntakeGenerally adequate for most vitamins and minerals.If carbohydrates are severely restricted (<20 grams):Diet may be low in Vitamin C, Beta Carotene and Fiber.Potassium and sodium levels should be monitored and may need to be supplemented during the first month of the diet, as they are additionally excreted in urine.
14 And Talk About Ketogenic, Very Low Carbohydrate Diets Let’s Switch Gears…..And Talk About Ketogenic,Very Low Carbohydrate Diets
15 The Role of Ketones In Human Physiology Diets containing less than 10-15% carbohydrates usually cause modest amounts of urinary ketosis.Ketones are produced as fuel from metabolized fats (acetyl-CoA) when carbohydrate-dervived pyruvate is low.Enzymes are present within all cells to convert ketones into fuel except in erythrocytes, cornea, lens and retina.Adapted from a slide by Eric Westman, MD.
16 The Role of Ketones (continued) Serum ketone levels are relatively low during low carbohydrate diets:Fed State mmol/L*Overnight Fast mmol/LLow Carb Ketogenic Diet 1-3 mmol/L**>20 Days Fasting 10 mmol/LDiabetic Ketoacidosis >25 mmol/L*Meckling et al. Can J Physiol Pharmacol 2002;80: ** Sharman MJ et al. J Nutr 2002;132:Adapted from a slide by Eric Westman, MD.
17 Short-Term Weight Loss Studies Early studies comparing low carb to low fat diets often used caloric levels of <1000 cal/day. These very low calorie studies did not show a weight loss difference between diets.*Most comparison studies today are using diets with moderate calorie deficits of kcal/day.The carbohydrate intake in current studies is usually about that of the Atkins “Induction” Diet (most strict level) and is generally 30 g/day.*Yang MU, Van Itallie TB. J Clin Invest. Sep 1976;58(3):
18 Foster GD, Wyatt HR, Hill JO, et al. N Engl J Med Foster GD, Wyatt HR, Hill JO, et al. N Engl J Med. May 22, 2003;348(21):First published RCT. Six month trial with follow-up to one year. Average baseline BMI of 34 kg/m2.Atkins Diet (all 4 levels) with ad lib kcal but controlled carbohydrate intake.Low cal diet kcal for women and kcal for men. Energy intake was 60% carb, 25% fat and 15% protein.N = 63; 43 women and 20 men. Low carb arm=33 and Low Cal arm=30. Average age is 44 years.No type 2 diabetes, lipid-lowering meds or other serious illness.
19 Weight Loss Results of Foster et al. Better participant retention in low carb arm at all measurement points -- 3,6 & 12 months, p<0.05.Did not report on actual calorie intakes of subjects.Weight loss significantly better in low carb group at 3 and 6 months but not at 12 months:3 Month Wt Loss:Low Carb ±5.0% Low Cal ± 3.7% (p<0.001).6 Month Wt Loss:Low Carb ± 6.5% Low Cal ± 5.6% (p<0.02).12 Month Wt Loss:Low Carb ± 6.7% Low Cal ± 6.3% (p<0.26).
20 Weight Loss Results of Foster et al. From p of Foster et al., 2003 NEJM.
21 From p. 2088 of Foster et al., 2003 NEJM. Lipid Results of Foster et al.From p of Foster et al., 2003 NEJM.
22 Blood Pressure and Insulin Sensitivity Results of Foster et al. Equivalent improvements for both groups at 3,6 and 12 months for:Systolic and diastolic blood pressure.Area under the glucose curve (OGT).Area under the insulin curve (OGT).Insulin sensitivity.
23 Summary Of Results From Short-Term Studies Low carb diets consistently produced more weight loss in RCTs that did not control the calorie levels between diets.Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DA. J Clin Endocrinol Metab. Apr 2003;88(4):Foster GD, Wyatt HR, Hill JO, et al. N Engl J Med. May 22, 2003;348(21):Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. May ;348(21):Westman EC, Yancy WS, Guyton JS. AHA. Nutrition Abstracts. Circulation (Supplement II). 2002;106(19).
24 Summary Of Results From Short-Term Studies cont. In a recent study where the calories were kept the same, the weight loss was fairly comparable between the Atkins Diet and the DASH Diet although there was a trend for greater weight loss by 1.3 kg in the Atkins group.Due to the small sample size in each group (n=13) in the Atkins group and (n=12) in the DASH group, and the short time the results are not definitive.Stadler D, Burden V, McMurry M, Gerhard G, Connor W, Karanja N. Presentation at Experimental Biology annual conference, April, 2003.Current RCT trials at the Albert Einstein College of Medicine and Harvard University are also trying to answer the question of diet composition per se affects weight loss rates.
25 Summary Of Results From Short-Term Studies cont. Low carbohydrate diets may produce more satiety and reduced appetite …. leading to decreased caloric intake.Increased satiety may explain generally lower drop- out rates in low carbohydrate groups. If there is increased satiety, is it due to protein?Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DA. J Clin Endocrinol Metab. Apr 2003;88(4):Foster GD, Wyatt HR, Hill JO, et al. N Engl J Med. May 22, 2003;348(21):Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. May ;348(21):Westman EC, Yancy WS, Guyton JS. AHA. Nutrition Abstracts. Circulation (Supplement II). 2002;106(19).
26 Summary Of Results From Short-Term Studies cont. A low carbohydrate weight loss diet produced a greater reduction than a low fat weight loss diet in the inflammatory markers C-reactive protein and serum amyloid A. Both markers are associated with cardiovascular risk.Unclear whether the better reduction in inflammatory markers with the low carb diet was related to greater weight loss in the low carb group or was independent of this effect.O’Brien KD, Brehm BJ, Seeley RJ, Werner M, Daneils, D,D’Alessio DA. AHA. Nutrition Abstracts. Circulation .(Supplement II) ;106(19).
27 Summary Of Results From Short-Term Studies cont. Preliminary evidence from 1 month study showed greater urinary acid and calcium excretion among overweight volunteers (BMI = 29.4 kg/m2) on a very low carbohydrate diet compared to their normal diet.Study found no metabolic acidosis. It did find increased urinary acid excretion that was due to the increase in sulfur-containing amino acids from protein foods and acidic ketone bodies. This may increase the risk of renal stones.Reddy ST, Wang CY, Sakhaee K, Brinkley L, Pak CY. Am J Kidney Dis. Aug 2002;40(2):
28 Summary Of Results From Short-Term Studies cont. Increased calcium excretion without compensatory increase in intestinal calcium absorption may lead to bone loss.However, it’s unclear whether if a low carb diet was used for a longer time period, whether there might be physiological adaptation to it. Longer term studies are needed.Do populations such as the Eskimos who have survived on very low carb diets show such adaptations?Reddy ST, Wang CY, Sakhaee K, Brinkley L, Pak CY. Am J Kidney Dis. Aug 2002;40(2):
29 Summary Of Results From Short-Term Studies cont. Low Carbohydrate Weight Loss Diets may work better for people with Metabolic Syndrome -- better weight loss, and greater improvements in triglyceride levels. Better weight loss tracks with insulin sensitivity improvements.Insulin sensitive participants lost more weight on the LF/HC diet compared to the HC/LC diet (13.56 ± kg compared to 6.12 ± 1.13 kg, p<0.01). Also there was a trend for improvements in insulin sensitvity in already IS participants on the LF/HC diet.
30 Summary Of Results From Short-Term Studies cont. Insulin resistant participants lost more weight on the HF/LC diet compared to the LF/HC diet (11.46 ± kg compared to 6.52 ± 0.98 kg, p<0.05). Also there was a trend for improvements in insulin sensitvity in insulin resistant participants on the HF/LC diet.Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. May ;348(21):Eckel RH, Drazin B. J. Investigative Med. 51:Suppl ; S383.
31 Summary Of Results From 2001 Low Carbohydrate Weight Loss Survey, N=6,088 Segal-Isaacson CJ, Segal-Isaacson AE, Wylie-Rosett, J. The Journal of The American Dietetic Association : S45.More than half of the respondents (55.9%) were currently dieting to lose weight and their BMI was higher than those who were not trying (31.2 7.8 compared to 7.6; p < ).Those who were not currently dieting to lose weight reported they had lost an average of 36.2 25.6 lbs but had wanted to lose 56.3 41.3 lbs.The amount of weight these respondents reported they kept off for at least one year was at least lbs for 53.2% of the respondents and at least lbs for 37.4% of the respondents.
32 Summary Of Results From 2001 Low Carbohydrate Weight Loss Survey cont. Most respondents modified the diet they chose (60.2%). The most common modifications were adding more vegetables (29.0%), fruit (12.4%) or occasionally going off the diet (32.7%).The three most common diet likes were not feeling hungry (87.5%) or deprived (85.6%) and losing weight easily (74.1%).The three most common diet dislikes were bad breath (30.9%), light headedness (15.0%) and nausea (8.3%).
33 Current Low Carbohydrate Research At The Albert Einstein College of Medicine The CCARB Study: First long-term study on low carbohydrate dieters. Internet-based -- will follow each participant for at least three years. More than 50% of participants have objectively documented their weight and height through their healthcare provider. Will also assess lipid values in a subset. Website address is:The Metabolic Impact Study: Pilot controlled feeding study that uses isocaloric-isonitrogenous diets to determine whether a very low carbohydrate diet burns body fat more quickly than a moderate low fat diet. Uses stable isotopes to trace whether ingested fats are oxidized or stored; indirect calorimetry to measure energy expenditure and and MRI to measure body fat distribution.
34 Current Low Carbohydrate Research At The Albert Einstein College of Medicine cont. The Diabetes Dietary Study: Study on 74 adults with type 2 diabetes who also take insulin. Study will compare a one year trial of an Atkins-style low carbohydrate diet to the low fat diet used in the Diabetes Prevention Project.Call for more information on any of the three studies or at .
36 Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DA. J Clin Endocrinol Metab. Apr 2003;88(4):Six month RCT with 53 obese women comparing a low carb (<20 g/day for first two weeks then g/day) to a low calorie- 30% fat diet with calories at an estimate of resting energy expenditure.Weight loss was greater in the low carb group: 8.5 ± 1.0 kg compared to 3.9 ±1.0 kg.Blood pressure was normal in both groups and remained so during the trial.Lipids were normal in both groups but improved with weight loss in both groups.Fasting insulin and glucose decreased similarily in both groups.
37 Eckel RH, Drazin B. J. Investigative Med.51:Suppl 2.2003; S383. Controlled 16 week feeding trial with 24 obese adults who were randomized to either a low fat/high carb or a high fat/low carb diet. Participants were also stratified by insulin levels: <10 U/ml = insulin sensitive; >15 U/ml = insulin resistant.Diets were matched for energy with a 400 kcal deficit. The composition of the low fat/high carb diet (LF/LC) was 60% CHO, 20% fat, 20% protein. The composition of the high fat/low carb diet (HF/LC) was 40% CHO, 40% fat, 20% protein.All participants lost at least 5.82 kg.Insulin sensitive participants lost more weight on the LF/HC diet compared to the HC/LC diet (13.56 ± 1.60 kg compared to 6.12 ± kg, p<0.01). Also there was a trend for improvements in insulin sensitvity in already IS participants on the LF/HC diet.
38 Eckel RH, Drazin B. J. Investigative Med.51:Suppl 2.2003; S383 cont. Insulin resistant participants lost more weight on the HF/LC diet compared to the LF/HC diet (11.46 ± 1.37 kg compared to 6.52 ± kg, p<0.05). Also there was a trend for improvements in insulin sensitvity in insulin resistant participants on the HF/LC diet.There was no relationship between baseline fasting insulin levels and weight loss.The improvement in insulin sensitivity predicted the amount of weight loss, r=0.71.No significant changes in LDL or HDL. Triglycerides decreased in everyone but insulin resistant participants on the LF/HC diet.A high fat, low carbohydrate diet may be a more effective weight loss diet for insulin resistant obese people.
39 O’Brien KD, Brehm BJ, Seeley RJ, Werner M, Daneils, D,D’Alessio DA. AHA. Nutrition Abstracts. Circulation(Supplement II). 2002;106(19).RCT of 43 obese adults comparing effects of low fat diet versus low carbohydrate diet on the inflammatory markers C-reactive protein and serum amyloid A.Six month trial with adlib diet.Low fat diet: n=22, Energy distribution = CHO 55%; Fat 30%; Protein 15%Low carb diet: n=21, Energy distribution = CHO <10%; no other restriction.
40 O’Brien KD, Brehm BJ, Seeley RJ, Werner M, Daneils, D,D’Alessio DA. AHA. Nutrition Abstracts. Circulation(Supplement II). 2002;106(19). Continued.More weight loss in low carb group 6 months: -7.3 ± 4.7kg versus -2.8 ± 4.4 kg in low fat group.No reduction in inflammatory markers in low fat group but significant reduction in low carb group at 6 months: -33% reduction in CRP and -21% in serum amyloid A at 3 months.Unclear from abstract to what extent reduction in inflammatory markers was related to weight loss.
41 Reddy ST, Wang CY, Sakhaee K, Brinkley L, Pak CY. Am J Kidney Dis. Aug 2002;40(2):Purpose of study was to evaluate the effect low carb, high protein diets on acid-base balance, calcium metabolism and stone formation.10 volunteers with an average BMI of 29.4 kg/m2.Eight week trial: 2 weeks normal diet, 2 weeks at <20 g/day of carbs and 4 weeks at <35 g/day.No metabolic acidosis.Increased urinary acid excretion due to sulfer-containing amino acids from protein foods as well as acidic ketone bodies.
42 Reddy ST, Wang CY, Sakhaee K, Brinkley L, Pak CY. Am J Kidney Dis. Aug 2002;40(2): Continued.Also Increased urinary calcium excretion without compensatory increases in intestinal calcium absorption.No changes in serum potassium, chloride, CO2, calcium or phosporus but slightly lower sodium levels.No change in urinary uric acid, oxalate, sodium, potassium or total volume of urine.Authors conclude the net increase in acid (50 mEq/d) through the combined effects of a high protein-low carbohydrate diet may increase risk for renal stones and bone loss.
43 Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. May ;348(21):132 severely obese adults with an average BMI of 43 kg/m2.39% participants had diabetes and 43% metabolic syndrome.Six month RCT at a Phil. V.A. hospital.Low Carb: <30 g/day of carbs with no calorie restriction.Low Fat / LowCal: 30% dietary fat with 500 calorie deficit.Dietary compliance evaluated with 24 recalls.
44 Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. May ;348(21): Continued.More weight lost on low carb diet: 5.8 ± 8.6 kg compared to 1.9 ± 4.2 kg; p=0.002.Triglycerides decreased more in the low carb group.No other lipid differences.Fasting glucose decreased more in low carb group among its diabetic subjects with concommittant reductions in DM meds.Insulin sensititivity improved more in low carb group (this was only measured in non-diabetic participants of both groups).
45 Stadler D, Burden V, McMurry M, Gerhard G, Connor W, Karanja N. Presentation at ExperimentalBiology annual conference, April, 2003.Trial matched the caloric levels of 13 participants on the Atkins diet with another 12 participants on the DASH diet.The average ad lib calorie reduction on the Atkins diet was 68% of usual and the calorie intake of participants on the DASH diet was matched at 67% of usual.The participants were given meals prepared in a metabolic kitchen for 42 days.Although weight loss was not significantly different between the two diet groups, there was a trend for greater weight loss in the Atkins group by 1.3 kg.
46 Westman EC, Yancy WS, Edman JS, Tomlin KF, Perkins CE. Am J Med. Jul 2002;113(1):30-36.One-armed trial.41 of 51 adults (80%) completed six month study.Atkins Diet (adlib) with initially <25 g carbs + Atkins MVI suppl. Carbs increased to 50 g if 40% of wt loss achieved.Average weight loss 10.3 ± 5.9% p<0.001.Average fat loss of 2.9 ± 3.2% p<0.01 (skinfolds).Significant improvements in: systolic and diastolic BP, total cholesterol, LDL, triglycerides and HDL.Increases in urinary calcium and uric acid.
47 Westman EC, Yancy WS, Guyton JS. AHA. Nutrition Abstracts Westman EC, Yancy WS, Guyton JS. AHA. Nutrition Abstracts. Circulation (Supplement II). 2002;106(19).Six month RCT comparing Atkins Diet (<20 g/day Carbs) to Low Fat/Low Cal Diet (no composition given in abstract).MVI, Borage, Flaxseed and Fish Oils supplements given to low carb group.Mean BMI of 34.5 kg/m2 at baseline.Low Carb Group, n= 36; Low Fat Group n = 27.Greater weight loss in low carb group: 13.8% to 8.8%.Reduction in VLDL greater in low carb group.Both groups had a 73% reduction in small LDL and an overall increase in LDL particle size.The low carb group had a larger increase in large LDL particles.
48 Popular Weight Loss Diets: What’s The Evidence?Moderately High Protein Lower Carbohydrate(30% protein; <30% fat; 40% carbohydrate)Dr Manny NoakesSenior Research DietitianCSIRO Clinical Research UnitAustraliaHealth Sciences and Nutrition
49 Rationale for Moderately High Protein Intakes in Weight Loss? Emerging scientific evidence for effects on satietyDietary pattern that is nutritionally adequate
50 Emerging Scientific Evidence Lean body mass spared - glucose tolerant women(Piatti et al,1994)Increased satiety - glucose tolerant women(Latner & Schwartz, 1999)Thermic effects - obese, hyperinsulinaemic men(Hwalla Baba et al,1999)High protein/Low GI -25% decrease in ad libitum intake – obese men(Dumesnil et al 2001)Thermic effect of HP meal 28% greater – no change in REE - Type 2 diabetes (Luscombe et al 2002)Endocrine and metabolic improvements - women with PCOS(Moran et al 2003)
51 Zone vs Atkins vs Conventional Mean weight loss was 5.1 kg for those who completed the 12-week program.No significant differences in total weight, fat, or lean body mass loss by diet group.91 commenced study and 49 completed the 12 weeks. Attrition was substantial for all plansAtkins 43%,Zone 60%,Conventional 36%Landers P J Okla State Med Assoc. 2002
52 Protein vs Carbohydrate in ad libitum Fat Reduced Diet Skov et al 1999High-carbohydrate(HC, protein 12% energy) n=25High-protein(HP, protein 25% energy) n=25RESULTS AFTER 6 MONTHS5.1 kg in the HC group8.9 kg in the HP group (P < 0.001)More subjects lost > 10 kg in the HP group (35% vs 9%).HP diet decreased fasting plasma triglycerides significantly.
53 Increased Protein/Carb ratio in overweight women CHO/protein ratio3.5 (CHO Group)68g protein1.4 (Protein group)125g proteinLayman et al J Nutr. 2003
54 Increased Protein/Carb ratio in overweight women CHO/protein ratio3.5 (CHO Group)68g protein1.4 (Protein group)125g proteinLayman et al J Nutr. 2003
55 Weight Loss Weight Loss Weight LossMaintenanceHPWeight LossMaintenanceLPInterventions: Fat <30%, sat fat <10% 6500kJHigh Protein (HP) - 28% E Protein, 42% E CHOLow Protein (LP) - 16% E Protein, 55% E CHOParker B, Noakes M, Luscombe N, Clifton P.Diabetes Care. 2002
57 Dietary Protein Effects in Type 2 Diabetes Total fat mass significantly decreased in women on HP diet (12.4%)Abdominal fat mass significantly decreased in women on HP diet (12%)Significant decrease in LDL cholesterol levels on HP diet (5.7%)Parker B, Noakes M, Luscombe N, Clifton P.Diabetes Care. 2002
58 High Protein Diets and Renal Function in D2 Urinary albumin excretion was not affected by dietary protein during weight loss:n=19 with microalbuminuriaHP diet: 24.2 to 19.8 mg/l (n=12)LP diet: 4.3 to 3.5 mg/l (n=7)Parker B, Noakes M, Luscombe N, Clifton P.Diabetes Care. 2002
59 High Protein Diets In Subjects With High Insulin Diet effect p < 0.05126.96.36.199.82481216WeekTriglycerides (mMol/L)High carbHighProtein9.6%22.8%Farnsworth et al AJCN 2003
60 Insulin Response to Test Meals Diet effect p < 0.052040608010012014030180Time (min)Insulin (mU/l)High ProteinHigh CarbFarnsworth et al AJCN 2003
61 Glucose Response to Test Meals Diet effect p = 0.0204567893060120180Time (min)Glucose (mMol/l)High ProteinHigh carbFarnsworth et al AJCN 2003
62 Aim:To compare a high protein weight loss diet with a high carbohydrate diet onweight loss and body compositionnutrient statusbone turnover markersmeasures of heart disease riskin women over 12 weeks… ..and subsequently follow up for 1 yearDiets:1. High carbohydrate2. High protein, high red meat
66 Weight Loss by Triglyceride Status Sig diet effectP=0.023HighproteinHighcarb
67 Total And Midriff Fat Loss Dexa Data* Sig diet effectHighproteinHighcarb
68 Triglycerides by TG status HIGH TGDiet X TG interaction P=0.0110%28%LOW TG
69 (Effect of diet P=0.07, with overall ANOVA p=0.019) after accounting for TG status
70 Significant effect of diet P=0.005 suggesting lower energy intake on high protein diet
71 Calcium Excretion Calcium excretion decreased on both diets reference rangemmol/24hrCalcium excretion mmol/24hrweek 0week12High proteinHigh carb
72 Women with type 2 diabetes Subjects with elevated insulin levels CONCLUSIONThere is emerging evidence that moderately high protein lower carbohydrate diets for weight loss are advantageous to conventional high carbohydrate diets for:Women with high TGWomen with type 2 diabetesSubjects with elevated insulin levelsThere is no evidence that such moderate dietary patterns pose any health risks although more extended studies in overweight subjects with mild renal impairment are necessary to confirm safety in this group
73 Popular Weight Loss Diets: What’s the Evidence Popular Weight Loss Diets: What’s the Evidence? Low-fat and Very Low-fat DietsKeith-Thomas Ayoob, EdD, RD, FADAAlbert Einstein College of MedicineJuly 17, 2003
74 Macronutrient distribution American Heart Association-style< 30% fat15% protein55% CHOVery low-fat diet10-15% fat12-15% protein72-75% CHO
75 Typical dinner--AHA-style 3-oz. Broiled salmon2/3 cup rice1/2 cup mixed vegetables1 cup salad greens, 2 tsp. Vinaigrette1 slice whole wheat bread1 tsp. butter1/4 cantaloupe
76 Typical dinner--very low-fat 3-oz. baked whitefish1-1/2 cups sauteed collard greensbaked sweet potato1/2 cup wild rice pilafbaked apple
77 Low-fat Diets: Weight Loss 2003 review by Pirozzo, et alCriteria for inclusionRandomized Ccontrolled Trial (RCT) ofLow- Fat vs. other wt loss dietsprimary purpose was wt. LossAge > 18 years & BMI > 25 at baselineFollowed for at least 6 months“Low fat diet” = < 30% of calories from fatPirozzo, S. et al. Cochrane Database of Systematic Reviews. 1, 2003.
78 Low-fat Diets: Weight Loss Four 6-months studiesFive 12-month studiesThree 18-months studiesResult:No significant differences compared to other weight loss diets
79 Low-fat Diets: Weight Loss Meta-analysis of 34 studies,2-12 months durationad lib low-fat diets vs. controlsResult:3.3 kg loss in low-fat groups (sig.)Main factors:degree of dietary fat reductionpre-treatment body weightAstrup A, et al. Int J Obes Relat Met Dis Dec; 24(12):1545
80 Low-fat Diets: Long-term Success Review by Ayyad & Anderson, 2000Criteria for inclusion:adultsFollow up of > 3 yearsFollow up of > 50% of original study groupCriteria for long-term success:Maintain > 9-11 kg or all weight initially lostAyyad C and Anderson T. Obesity Reviews, 2000; 1:113-9
81 Low-fat Diets: Long-term Success Overall, 15% of followed-up subjects met criteria for successDiet alone = 15% met follow-up successDiet + group therapy = 27% met successDiet & behavior mod. = 14% met successActive follow-up better than passive for long term success (19% vs. 10%)
83 RESULTS: Low-fat vs moderate & high-fat diets % body weight lost at 12 monthsNSWt loss associated with calories ONLY
84 Low-fat diets and satiety Review of low-energy diets, glycemic index (GI), and obesityLow-GI foods = Increased satietylow-fat, low-GI-based diets = promote satiety and may therefore promote weight losshigh-GI diets = weight gain and lower satietySimilar in animal studiesBrand-Miller et al. Am J Clin Nutr. 76(1):281S, 2002 July
85 Long-term Compliance/Maintenance McGuire et alrandom digit phone surveymaintainers = lost > 10% of wt. , maintained for > 1 yr.69 Maintainers, 56 regainers, 113 wt-stable controlsMcGuire et al. Int J of Ob & Rel Metab Disord:J of the Int Assoc Study of Ob. 23(12):1314, 1999 Dec
86 Long-term Compliance/Maintenance Common factors for success:lower-fat intake than regainers/controlsbehavior strategies used more than regainersmore physically active, esp. strenuous activity
87 National Weight Control Registry Maintained a loss of > 25 lb. for > 1 yearlost weight by different methodsMaintainers:low fat, modest calorie intakePhysically active 4-5 days/week
88 LF Diets and Drop-outs Problem in many studies Most studies are 6 months or lessOnly count those who completed studyLonger studies self-selectSeveral studies do show compliance after 1 yearDrop-out rate: 11-40% (Pirozzi, et al)
90 C-reactive protein (CRP) & low-fat diets CRP strongly associated with BMILF diet (15% fat, 62% CHO) wksCRP significantly with Low-Fat/low- calorie diet and wt lossOther dietary composition not investigatedHeilbron et al. Arterioscl, Thromb & Vasc Biol. 21(6):968, 2001 June
91 LDL & low-fat diets 2001 review by Krauss LDL-A = desirable large, fluffy LDLLDL-B = small, dense LDL (atherogenic)Conclusion:genes play a roleLDL-B: benefits from a low-fat dietLDL-A: no benefits from low-fat diet IF isocaloric, & may convert to LDL-B profileCAVEAT: studies are often short-term, not all hi-CHO diets are alikeKrauss. J of Nutr. 131(2) 340S; 2001 Feb
92 HDL & low-fat diets Meta-analysis of studies > 2months LF diet lowered HDL, less so when fed ad lib than isoenergeticallyEpi studies consistently show populations with LF diets and low-HDL have LOW atherosclerosisDiets high in fruits, vegetables and grain fiber promote less atherosclerosis, cancerJequier E and Bray G. Am J of Med. 113(9) supp. 2: Dec
93 Effect of type and amount of fat on HDL/lipids Meta-analysis of 60 studies, Mensink et alConclusion:Replacing fat with CHO isoenergetically may increase total/HDL ratioReplacing fat with CHO and reducing calories could have same effect as replacing SFA with MUFA and PUFAReplacing trans-fat with MUFA/PUFA had best effect on blood lipidsCaveat: Results are general but the need is individualMensink, RP et al. AM J Clin Nutr. 77(5); 1146, 2003 May
94 LF diets and insulin Review by Brand-Miller, et al Low-fat, hi-CHO, hi-GI diets may increase insulin responseBUT low-fat, low glycemic diets may promote wt loss via increased satiety, lowered insulin responseExercise improves insulin responseBrand-Miller et al. Am J Clin Nutr. 76(1):281S, 2002 July
95 CONCLUSIONSCalories count more than fat: Low energy diets are more effective at producing weight loss than low-fat dietsBUT low-fat diets may make it easier to reduce total energy intake
96 CONCLUSIONS Risks of Low-fat diets Benefits Difficult long-term compliance on very low-fat dietincreases with close follow-up and group supporttype of CHO may affect outcome, possibly by altering satietyBenefitsStrong association with long-term maintenanceLF, hi-CHO, hi-fiber diet reduces other health risks and is usually rich in vitamins, minerals, and phytonutrients
97 UNANSWERED QUESTIONS LONGER STUDIES NEEDED! Do metabolic parameters show adaptation over time? Is long-term adaptation different?Should physical activity and/or metabolic profile affect recommendation of diet type?