Potatoes or Bacon: Which is better for weight loss? Laura Zakowski, MD

Objectives n Compare various low carbohydrate diets n Review risks of low carbohydrate diets n Define net carbohydrates n Define glycemic index n Review year long weight loss studies

Copyright restrictions may apply. Mokdad, A. H. et al. JAMA 2003;289: Prevalence of Obesity and Diagnosed Diabetes Among US Adults, 1991 and 2001

55 year old female interested in weight loss n Wants to take medications or use the Atkin’s diet n PMH: u Diabetes u Hypercholesterolemia u Hypertension u Obesity

YearWeightHgbA1cTx Diet and exercise Phen-fen % 11/13/ %

Atkin’s diet

Atkin’s Diet atkins.com n Phase 1: Induction u 20 gm carbs n Phase 2: On going weight loss u Add 5 gms carbs per week n Phase 3: Premaintenance u Add 10 gms per week n Phase 4: Lifetime Maintenance u Usually about gms per day

“Net Carbs” Net carbs = Total carbs – (Fiber + “carbs not turned in blood glucose”) u Maltitol u Sucralose u Glycerin u Polydextrose

Zone diet zoneperfect.com

Zone diet

Glycemic index n The rate at which a carbohydrate enters the blood stream as glucose n Low glycemic index: fruits and vegetables n High glycemic index: breads, pasta, grains, starches

Unfavorable carbohydrates n Breads, Rice, Pasta, Potatoes n Bananas n Carrots n Corn n Peas n Pineapple n Watermelon

South Beach Diet southbeachdiet.com n Phase 1 u Limit carbs u No: Breads, rice, potatoes, pasta, baked goods, fruit n Phase 2 u Add back carbs in moderation u Based on glycemic index n Phase 3 u “A diet for life”

Risks of low carbohydrate diets n Bone loss: u Protein affects how calcium is handled in the kidney u Study over 9 weeks showed no change in: F Urinary calcium excretion F 25OH Vit D, PTH u Evidence of less bone turnover in high protein group u Conclusion: no negative effect on Ca Dawson-Hughes, et al. J Clin Endocrinol Metab 2004; 89:

Risks of low carbohydrate diets n Hypercholesterolemia n Impaired hepatic and renal function n Accumulation of ketones n Salt and water depletion n Constipation

Systematic review n Randomized controlled and cross over studies: u 7 low carb diets and 75 higher carb n OK studies u 34 low carb and 130 higher carb n None longer than 90 days n Very limited studies of patients u Over 50 u With co-morbid illnesses Bravata, et al. JAMA2003;289:

Systematic review n No evidence of adverse effects on u Serum lipids u Serum glucose u Blood pressure n Areas for further study: u Long-term outcomes u Ethnic groups u Exercise u Intention to treat analyses

What about longer studies? n 6 month and 12 month outcome studies n Evaluating u Weight loss u Diabetes outcomes u Cholesterol values

Low carb vs Conventional Diet: One year outcome n Philadelphia VA outpatient practice n BMI > 35 kg/m2 n N = 132 n All: weekly then monthly counseling n Randomized: Low carbohydrate or Low fat Stern, L. et. al. Ann Intern Med 2004;140:

Study subjects n 60% African American n 80% Male n 40% diabetic n 50% hyperlipidemic n 60% hypertensive

Are the results likely to be valid? n Patients randomized and similar n Follow-up long and complete?? u 1 year study u Continued in entire study 66% u Final weight: 96% n Patients analyzed in their group n Patients not blind; Researchers?? n Groups treated equally

Stern, L. et. al. Ann Intern Med 2004;140:

Dietary results Baseline 1 Year CALORIES Not sig Low calorie Low carb CARBS p = 0.01 Low calorie Low carb

Blood test results Baseline 1 year TGs p = Low cal Low carb HDL p = Low cal 4136 Low carb 4140 HgbA1c Not sig Low cal Low carb

Conclusions n Needed 284 persons to show a difference n Is the low carb diet less sustainable? n What are the long term outcomes?

A second Study: One year outcome n N = 63 n 68% female n Excluded patients with diabetes n Randomized to Atkins or low fat u 60% carbs, 25% fat, 15% protein n No counseling sessions Foster, et al. NEJM 2003;348:

A second Study: One year outcome n 37 subjects completed the study n HDL increased significantly u P = 0.04 u 11% change n TGs decreased significantly u P = 0.04 u 17% change n Diastolic BP and insulin sensitivity better in both groups

Foster, et al. NEJM 2003;348:

Conclusions n Similar findings to other weight loss treatments n High attrition n How safe is it?

DateWeightHgbA1cTx 11/13/ % Zone diet 2/09/ % 5/20/ %