OBESITY: WHICH DIET IS BEST? Ronen Gurfinkel, PGY4 May 30, 2012

Objectives Review the background of commonly used diets in overweight and obese patients Review the literature behind commonly used diets

Background Obesity Risk factor for: Cardiovascular disease Hypertension Type 2 diabetes Cancer Associated with Sleep apnea Osteoarthritis Reduced quality of life

CMAJ 2007

Background Epidemiology Second most preventable cause of death 66% of adults in U.S. are either overweight or obese

Background Benefits of weight-loss Decreased risk of obesity-related diseases Decreased risk of mortality

Weight-loss Done by creating a negative energy balance Reduction of 500 kcal per day less than what is required to maintain current body weight Should lead to loss of 0.45 kg (1 lb) per week Successful weight-loss 5% reduction in initial body weight Maintained for at least 1 year

Weight-loss Weight-loss therapies Dietary intervention Exercise programs Psychotherapy Pharmacotherapy Surgery

Diets Commonly used dietary interventions: Low-carbohydrate Low-fat Low-calorie Other diets: Glycemic index diet

Low-carbohydrate Diets Restrict caloric intake by reducing consumption of carbohydrates 300 g/day  g/day Rationale: carb restriction causes liver to convert fat into fatty acids and ketones (ketosis)  decreases hunger Popular Low-carb diets Atkins Diet Carbohydrate Addict’s Diet Zone Diet South Beach Diet

Low-carb Diets Sherer EL and Sherer JA. JAAPA 2008

Low-fat Diets Usually restrict fat consumption to less than 10% of total caloric intake Encourage consumption of fruits, vegetables, and complex carbohydrates Rely on complex carbohydrates and fiber to induce satiety Rationale: reduced fat leads to reduced calories and thus a negative energy balance Popular low-fat diets: Ornish Diet Pritikin Diet

Low-fat Diets Sherer EL and Sherer JA. JAAPA 2008

Low-calorie Diets Encourage lower caloric intake through portion control Rationale: decreased caloric intake leads to negative energy balance Programs may provide nutritional/behavioral counseling and physical activity recommendations Popular low-calorie diets Weight Watchers Jenny Craig

Low-calorie Diets Sherer EL and Sherer JA. JAAPA 2008

Weight Watchers

Which Diet is Best? High-protein/low-carb vs high-carb/low-fat Some studies show high-protein/low-carb better Other studies show no difference Very-high-carb/very-low-fat vegetarian diet Better than conventional high-carb/low-fat Low-carb vs low-fat Low-carb better in one study (Shai et al, 2008) High-protein vs low-protein No difference in one study (Due et al, 2004)

Dansinger et al, JAMA 2005 Objective: Assess adherence rates and effectiveness of 4 popular diets for weight loss and cardiac risk factor reduction

Dansinger et al, JAMA 2005 Design: Single-center (academic) Randomized trial Single blinded Power: 40 participants in each group needed to achieve 80% power to detect weight change 2% from baseline or 3% between diets Analysis: Intent-to-treat: missing data replaced with baseline data Completers analysis: Missing data excluded Participants: Adults age Overweight or obese (BMI 27-42) Known hypertension, dyslipidemia, or fasting hyperglycemia

Dansinger et al, JAMA 2005 Intervention: Randomly assigned to one of four diets Atkins Diet (carb restriction) Carb restriction to < 20 g/day with gradual increase to 50 g/day Zone Diet (macronutrient balance) 40%-30%-30% balance of calories from carb-fat-protein Weight Watchers Diet (calorie restriction) Point system aiming for points/day (1 point = 50 kcal) Ornish Diet (fat restriction) Vegetarian diet with 10% of calories from fat After 2 months of maximum effort, participants selected own levels of adherence 4 one-hour sessions with MD & RD over first 2 months

Dansinger et al, JAMA 2005 Other recommendations: Multivitamin 60 minutes of exercise weekly Avoid commercial support services

Dansinger et al, JAMA 2005 Main Outcome: One-year changes in baseline weight and cardiac risk factors Measured at baseline, 2, 6, and 12 months Self-selected dietary adherence rates per self-report 3-day food records at 1, 2, 6, and 12-months Monthly telephone contact for self-rated adherence over past 30 days using 10 point scale

Dansinger et al, JAMA 2005 Results No difference between calories or macronutrients at baseline Mean total energy intake 2059 calories

Dansinger et al, JAMA 2005 Results Calorie reduction from baseline at 1 year: (P< 0.05 for each, P= 0.70 between diets) Atkins: -138 Zone: -251 Weight Watchers: -244 Ornish: -192

Dansinger et al, JAMA 2005 Results Weight loss at 1 year Modest weight loss was statistically significant for each diet 25% had weight loss of 5% of initial body weight 10% had weight loss of 10% of initial body weight Similar weight loss across all 4 diets (P=0.40) Results by gender Women: weight loss 2.4 kg, waist circumference 2.3 cm Men: weight loss 3.3 kg, waist circumference 3.1 cm Self-reported adherence strongly associated with weight loss Top tertile of adherence lost 7% of initial body weight

Dansinger et al, JAMA 2005 Results All diets lead to some improvement in cardiac risk factors at 1 year (intent-to-treat) Reduced LDL cholesterol (except Atkins) Increased HDL cholesterol (except Ornish) No change in triglycerides, BP, fasting glucose Reduced CRP (except Zone) Similar (but larger changes) seen in completers analysis Amount of weight loss predicted the amount of improvement in some of the cardiac risk factors

Dansinger et al, JAMA 2005 Results Adherence decreased with time, to similar extent in all groups At 1 year, 25% of participants in each group had self-reported adherence 6/10

Dansinger et al, JAMA 2005 Discontinuation rates at 1 year: Ornish – 50% Atkins – 48% Zone – 35% Weight Watchers – 35% Reasons for discontinuation: Diet too hard to follow Diet not yielding enough weight loss

Dansinger et al, JAMA 2005 Conclusions Each popular diet modestly reduced body weight and several cardiac risk factors at 1 year Overall dietary adherence rates were low, although increased adherence was associated with greater weight loss and cardiac risk factor reductions for each diet group

Sacks et al, NEJM 2009 Objective: Compare effects of 3 principal dietary macronutrients over longer period (and with fewer limitations) than previous trials

Sacks et al, NEJM 2009 Design: 2 centers Randomized trial Double blinded Power: Powered to detect 1.67 kg weight loss Analysis: Intent-to-treat: withdrawals after 6 months included, assumed weight re-gain 0.3kg/month, waist circumference regain 0.3cm/month Participants: Age Overweight or obese (BMI 25-40) Excluded DM, unstable CV disease, medications causing weight gain, insufficient motivation

Sacks et al, NEJM 2009 Intervention Randomized to 1 of 4 diets Diet% Fat% Protein% Carb Low-fat, Average-protein Low-fat, High-protein High-fat, Average-protein High-fat, High-protein

Sacks et al, NEJM 2009 Intervention Randomized to 1 of 4 diets Diet% Fat% Protein% Carb Low-fat, Average-protein Low-fat, High-protein High-fat, Average-protein High-fat, High-protein Low-fat High-fat

Sacks et al, NEJM 2009 Intervention Randomized to 1 of 4 diets Diet% Fat% Protein% Carb Low-fat, Average-protein Low-fat, High-protein High-fat, Average-protein High-fat, High-protein Low-fat High-fat High-protein Average-protein

Sacks et al, NEJM 2009 Intervention Randomized to 1 of 4 diets Diet% Fat% Protein% Carb Low-fat, Average-protein Low-fat, High-protein High-fat, Average-protein High-fat, High-protein Low-fat High-fat High-protein Average-protein High-carb Low-carb

Sacks et al, NEJM 2009 Intervention Randomized to 1 of 4 diets Diet% Fat% Protein% Carb Low-fat, Average-protein Low-fat, High-protein High-fat, Average-protein High-fat, High-protein Low-fat High-fat High-protein Average-protein

Sacks et al, NEJM 2009 Primary outcome: Change in body weight after 2 years Secondary outcome: Change in waist circumference after 2 years

Sacks et al, NEJM 2009 Other recommendations: Saturated fat < 8% Dietary fiber 20 g/day Cholesterol < 150 mg per 1000 kcal Low glycemic index foods Caloric deficit 750 kcal from baseline Moderate exercise 90 mins/week

Sacks et al, NEJM 2009 Follow-up Group sessions: First 6 months: weekly, 3 of 4 weeks After 6 months: weekly, 2 of 4 weeks Individual sessions: every 8 weeks Body weight and weight circumference measured at baseline and every 6 months

Sacks et al, NEJM 2009 Results 1638 participants screened 811 randomized (50%) 645 completed the study (80%)

Sacks et al, NEJM 2009 NEJM 2009

Figure 1NEJM 2009

Figure 2NEJM 2009

Sacks et al, NEJM 2009 Results Weight loss 5% at 2 years: 31-37% Weight loss 10% at 2 years: 14-15% All diets reduced CV risk factors at 6 months and at 2 years

NEJM 2009

Sacks et al, NEJM 2009 Results (for completers) Best LDL decrease Low-fat diets (5% vs 1%) Highest-carb diets (6% vs 1%) Best HDL increase Lowest-carb diets (9% vs 6%) Triglyceride decrease Similar in all groups (12-17%)

Sacks et al, NEJM 2009 Results (for completers) Fasting insulin decrease Not seen with highest-carb diet High-protein diet better (10% vs 4%, p=0.07) Blood pressure decrease Similar in all groups (1-2 mm Hg) Metabolic syndrome presence Similar in all groups (32%  19-22%)

Sacks et al, NEJM 2009 Results (intention-to-treat) Effect was about 30-40% smaller Mean macronutrient intake did not reach target levels in all groups Serious adverse events in 7%

Sacks et al, NEJM 2009 Conclusion: Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize

Glycemic Index - Background Glycemic index (GI) reflects type/quality of carbs in food, and how this food reacts metabolically Ranks how much a carb-rich foods will increase blood sugar levels Equals to additional area under the blood glucose response curve expressed as percent of response to a standard food (glucose or white bread)

Glycemic Index - Background

Low GI diet may have benefit on: Body weight and composition CV risk factors * Evidence is controversial Thomas TE, Elliott EJ, Baur J. Cochrane Database Syst Rev 2007

Larsen et al, NEJM 2010 Objective: Assess efficacy of moderate-fat diets that vary in protein content and glycemic index for preventing weight gain and obesity risk factors after weight loss Diogenes (Diet, Obesity, and Genes) study

Larsen et al, NEJM 2010 Design: Pan-European, multi-centre Randomized trial Analysis: Intention-to-treat and completers Participants: Families with 1+ adult age and 1+ children age 5-17 Overweight and obese (BMI 27-45)

Larsen et al, NEJM 2010 Intervention: 8-week low-calorie diet (800 kcal/day) If achieved weight loss >8%, randomly assigned to 1 of 5 diets (maintenance) for 26 weeks Low-protein (13%) + low GI Low-protein (13%) + high GI High-protein (25%) + low GI High-protein (25%) + high GI Control diet

Larsen et al, NEJM 2010 Follow-up Dietary counseling weekly x 6, then monthly

Larsen et al, NEJM 2010 Mean initial weight loss: 11 kg GI 4.7 units lower in low-GI vs high-GI Weight regain Lower in high-protein diets vs low-protein diets (0.93 kg difference) Lower in low-GI diets vs high-GI diets (0.95 kg difference) Further weight loss (> 5%) More likely in high-protein groups (OR 1.92) More likely in low-GI groups (OR 2.54)

Larsen et al, NEJM 2010 Completion/Drop-outs Overall completion rate 71% Lower rate in the high-protein diets and low-GI diets (26.4% and 25.6%) vs low-protein/high-GI diet (37.4%) Adverse events (serious, n=4) Abdominal pain Cholecystectomy

Larsen et al, NEJM 2010 Conclusion: Increase in protein and decrease in GI helped maintain weight loss, and was more likely associated with adherence

Take Home Messages No specific macronutrient regimen has been proven to be superior Diets can be tailored to individual preferences Low glycemic index foods may have Any type of diet leading to calorie reduction will lead to weight loss

References Sherer EL, Sherer JA. Examining the most popular weight loss diets: How effective are they? JAAPA 2008; Dansinger et al. Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction. JAMA 2005; Sacks et al. Comparison of Weight-loss Diets with Different Compositions of Fat, Protein, and Carbohydrates. N Engl J Med 2009; Larsen TM, Dalskov S-M, van Baak M, et al. Diets with high or low protein content and glycemic index for weight- loss maintenance. N Engl J Med 2010; 363:2102–2113

Questions?