Weight Loss: Comparing LowCarbohydrate, Mediterranean, and LowFat Diets

1
Weight Loss Comparing Low-Carbohydrate,
Mediterranean, and Low-Fat Diets

• Kate Neuhausen, MD
• Family and Community Medicine
• Resident at UCSF/SFGH
• September 3, 2008

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Intro Low-Fat Diet

• American Heart Association guidelines
• Energy intake 1500 kcal per day for women and
  1800 kcal per day for men
• Distribution of calories 30 from fat, 10 from
  saturated fat
• Intake of 300 mg cholesterol per day
• Dietary recommendations
• Consume low-fat grains, vegetables, fruits, and
  legumes
• Limit additional fats, sweets, high-fat snacks

3
Source http//www.vpul.upenn.edu/ohe/library/fitn
ess/foodpyramid.htm
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Intro Mediterranean Diet

• Moderate-fat, restricted-calorie
• Energy intake 1500 kcal per day for women and
  1800 kcal per day for men
• Goal distribution less than 35 calories from fat
• Dietary recommendations
• Consume vegetables, fish, and poultry
• Limit red meat in diet
• Consume 30 to 45 g of olive oil and handful of
  nuts (5-7 nuts) per day

5
http//www.revolutionhealth.com/healthy-living/foo
d-nutrition/food-groups-pyramids-overviews.com
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Intro Low-Carbohydrate Diet

• Non-restricted calorie diet (Atkins diet)
• Goal consumption 20 g of carbohydrates per day
  for 2-month induction phase with gradual increase
  to max of 120 g per day to maintain weight loss
• No limit on intake of total calories, protein,
  and fat
• Dietary recommendations
• Choose vegetarian sources of fat and protein
• Avoid trans fat

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Source http//thedivinelowcarb.blogspot.com/2007/
07/anti-food-dilemma.html
8
Source http//www.revolutionhealth.com/healthy-li
ving/food-nutrition/food-groups-pyramids-overview
9
Source http//www.revolutionhealth.com/healthy-li
ving/food-nutrition/food-groups-pyramids-overviews
.com
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Methods - Patients

• July 2005 July 2007
• On-site workplace medical clinic in Dimona,
  Isreal
• Men and women ages 40-65
• BMI at least 27 or presence of Type 2 DM or
  coronary heart disease
• Exclusion Criteria
• Pregnancy or breastfeeding
• Cr gt 2
• Liver dysfunction (greater 2x increase AST/ALT)
• GI problems preventing adherence to test diet
• Cancer

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Methods Study Design

• Two-year Randomized Controlled Trial
• Efficacy trial optimal circumstances
• Participants randomly assigned to three diet
  groups low-fat, low-carbohydrate, and
  Mediterranean
• Block randomization by sex, age, BMI, history of
  coronary heart disease, history of Type 2 DM, and
  current use of statins

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Methods Study Design

• Intensive dietary counseling with nutritionists
  for total of 18 session of 90 minutes each
• Motivational phone calls lasting 10-15 min by
  dietitians six times during 2-year interval with
  participants having difficulties adhering to diet
• Labeling of all meals in cafeteria with number of
  calories, grams of carbs, fat, and saturated fat
  with color coding according to diet group
• Adherence evaluated by validated electronic
  food-frequency questionnaires self-administered
  at workplace at baseline, 6, 12, 24 months of
  follow-up

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Methods Study Design

• Participants were weighed without shoes every
  month
• BMI was calculated, and waist circumference
  measured monthly
• BP was measured every 3 months with automated
  system after 5 minutes of rest
• Blood samples obtained at 8 AM after 12-hour fast
  at baseline, 6, 12, and 25 months

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Methods - Outcomes

• Weight Loss
• BMI
• Waist circumference
• BP
• HbA1c
• Fasting lipids LDL, HLD, triglycerides,
  cholesterol
• Fasting plasma glucose and plasma insulin
• Biomarkers CRP, adiponectin, leptin

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Results Adherence

• Baseline characteristics
• Mean age 52 years
• Mean BMI 31
• 86 men
• Rates of adherence
• Overall 95.4 at 12 months 84.6 at 24 months
• Low-fat 90.4 at 24 months
• Mediterranean 85.3 at 24 months
• Low-carbohydrate 78.0 at 24 months
• Medication changes during study not significantly
  different among groups
• 20 participants initiated BP treatment
• 5 initiated meds for glycemic control 1 reduced
  dosage
• 4 started and 3 stopped cholesterol-lowering
  therapy

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Results Dietary Intake at 24 months

• Low-fat group lower intake of saturated fat
• Energy change-572.5 kcal/day from baseline
• Carbs 50.7 (-82.8 g/day)
• Protein 19.0 (-19.8 g/day)
• Fat 30.0 (-18.9 g/day)
• Saturated fat 9.6 (-6.2 g/day)
• Change in monounsaturated saturated fat ratio
  0.02
• Change in cholesterol -94.2 mg/day
• Change in dietary fiber -4.7 g/day
• Level of physical activity 21.4 MET/wk
• Detectable urine ketone bodies 4.8 participants

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Results Dietary Intake at 24 months

• Mediterranean group higher ratio of
  mono-saturated to saturated fat and higher intake
  of dietary fiber
• Energy change-371.9 kcal/day from baseline
• Carbs 50.2 (-50.5 g/day)
• Protein 18.8 (-17.5 g/day)
• Fat 33.1 (-10.5 g/day)
• Saturated fat 9.6 (4.6 g/day)
• Change in monounsaturated saturated fat ratio
  0.11
• Change in cholesterol -94.6 kg/day
• Change in dietary fiber 0.29 g/day
• Level of physical activity 15.6 MET/wk
• Detectable urine ketone bodies 2.8 participants

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Results Dietary Intake at 24 months

• Low-Carb group lower intake of carbs, higher
  intakes of protein, total fat, saturated fat, and
  total cholesterol
• Energy change -550 kcal/day from baseline
• Carbs 40.4 (-129.8 g/day)
• Protein 21.8 (-6.9 g/day)
• Fat 39.1 (-1.7 g/day)
• Saturated Fat 12.2 (0.56 g/day)
• Change in monounsaturated saturated fat ratio
  -0.01
• Change in cholesterol 6.51 kg/day
• Change in dietary fiber - 10.o g/day
• Level of physical activity 16.3 MET/wk
• Detectable urine ketone bodies 8.3 participants

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Results Weight Loss at 24 months

• Phase of maximum weight loss from 1-6 months
• Maintenance phase from 7-24 months
• Overall weight loss among 322 participants at 24
  months
• Low-fat group -2.9 /- 4.2 kg
• Mediterranean -4.4 /- 6.0 kg
• Low-carb group -4.7 /- 6.5 kg
• Weight loss among 277 male participants at 24
  months
• Low-fat group -3.4 kg
• Mediterranean -4.0 kg
• Low-carb group -4.9 kg
• Weight loss among 45 female participants at 24
  months
• Low-fat group -0.1 kg
• Mediterranean -6.2 kg
• Low carb group - 2.4 kg

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Weight Change during 2 years according to diet
group
Source Shai I et al. N Engl J Med
2008359229-241
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Results - BMI, Waist Circumference, BP at 24
months

• Mean BMI changes
• Low-fat group -1.0 /- 1.4
• Mediterranean -1.5 /- 2.2
• Low-carb group -1.5 /- 2.1
• Mean Waist Circumference Changes
• Low-fat group -2.8 /- 4.3 cm
• Mediterranean -3.5 /- 5.1 cm
• Low-carb group -3.8 /- 5.2 cm
• Mean BP Decrease
• Low-fat group -4.3/0.9
• Mediterranean -5.5/2.2
• Low-carb group -3.9/0.8

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Results - Fasting Lipid Profile at 24 months

• HDL Cholesterol increased in all groups with
  greatest increase in low-carb group
• Low-fat group 6.4 mg/dl
• Mediterranean 6.3 mg/dl
• Low-carb group 8.4 mg/dl
• Triglycerides decreased significantly in low-carb
  and Mediterranean groups compared to low-fat
  group
• Low-fat group -2.8 mg/dl
• Mediterranean -21.8 mg/dl
• Low-carb group -23.7 mg/dl

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Results Fasting Lipid Profile at 24 months

• LDL Cholesterol no significant changes within or
  between groups
• Low-fat group -0.05 mg/dl
• Mediterranean -5.6 mg/dl
• Low-carb group -3.0 mg/dl
• Ratio of Total Cholesterol HDL decreased in all
  groups with greatest improvement in low carb
  group
• Low-fat group -0.6 mg/dl
• Mediterranean -0.9 mg/dl
• Low-carb group -1.1 mg/dl

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Change in Fasting Lipid Profile over 2 yrs
Low-fat group -2.8 /- 4.3 cm Mediterranean
-3.5 /- 5.1 cm Low-carb group -3.8 /- 5.2 cm
Source Shai I et al. N Engl J Med
2008359229-241
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Discussion

• Low-fat, Mediterranean and low-carb (Atkins)
  diets produced weight loss in a group of
  moderately obese participants
• Women lost significantly more weight with
  Mediterranean diet vs. low-fat and low-carb diets
• Mediterranean and low-carb diets had beneficial
  metabolic effects
• Similar caloric deficit achieved in all diet
  groups
• No decrease in need for medications among
  participants
• Continued improvement of biomarkers over 24
  months despite achievement of maximum weight loss
  by 5 months suggests that healthy diet has
  benefits beyond weight reduction

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JAMA Weight Loss Study

• Randomized control trial conducted over 12
  months of 311 overwight/obese (BMI 27-40)
  non-diabetic, premenopausal women recruited from
  community
• Compared Atkins (very low-carb), Zone (low carb),
  LEARN (low-fat, high carb), Ornish (very high
  carb)
• Results Women in Atkins diet group lost more
  weight and had more favorable metabolic effects
  (higher HDL and lower triglycerides) after 12
  months than women in Zone, LEARN, and Ornish diet
  groups

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Key Similarities

• Studies compared different, limited diets with
  different compositions of fat, carbs, and protein
  
• All diets (low-fat, low-carb, etc) helped
  participants lose weight but Atkins worked best
  and resulted in greatest weight loss
• Atkins has favorable metabolic effects, resulting
  in greatest increase in HDL and greatest decrease
  in triglycerides in both studies

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Key Differences

• In NEJM article, women lost most weight with
  Mediterranean diet while in JAMA article, women
  lost most weight with Atkins diet
• JAMA article did not include Mediterranean diet
• NEJM article measured more sustained weight loss
  over two years vs. one year in JAMA article
• JAMA article statistically adjusted for weight
  loss differences among groups and found a
  combined effect of benefit for Atkins diet
  attributable to both increased weight loss and
  dietary composition

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Strengths

• Long duration of study (follow-up over 2 years)
• One-phase design all participants started
  simultaneously
• Excellent adherence to diets
• Consistent data, participants successfully
  changed dietary intake
• No missing data used intention to treat for
  patients lost to follow-up
• Multiple measurements over time
• Frequency matched for effect possible effect
  modifiers during randomization (BMI, CAD, Type II
  DM, statin use)

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Limitations

• Unclear primary vs. secondary outcomes
• Homogenous population of Israelis
• Limited number of women enrolled in study
• Intense intervention extremely difficult to
  replicate 24 hours counseling by nutritionist
• Workplace environment difficult to generalize
  results to other outpatient settings
• Difficult to control for effect of different
  amounts of exercise between different groups

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Bottom Line

• Significant weight loss over 2-years with all
  three diets
• low fat, Mediterranean, and low-carb
• Low-carb and Mediterranean diets could be
  discussed w/ patients in clinical practice as
  options if they are more consistent w/ cultural
  or personal dietary practices
• Diets should be individualized according to
  personal preferences and metabolic needs
• Mediterranean diet shows high efficacy in weight
  loss for women and should be discussed w/ female
  patients
• Key may be encouraging patients to decrease
  calorie consumption (smaller portions, etc)
• Low-carb, non-restricted calorie diet is an
  option for patients who wont follow low-fat or
  restricted calorie diet

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Citations

• Shia, I., et al. Weight Loss with a
  Low-Carbohydrate, Mediterranean, or Low-Fat Diet.
  N Engl J Med 2008359220-41.
• Gardner, C.D., et al. Comparison of the Atkins,
  Zone, Ornish, and LEARN Diets for Change in
  Weight and Related Risk Factors Among Overweight
  Menopausal Women. JAMA. 2007297969-77.