Popular Weight Loss Popular Weight Loss Diets: Diets:

What’s The Evidence? What’s The Evidence? • Low Carbohydrate DietsLow Carbohydrate Diets

CJ Segal-Isaacson, EdD, RDCJ Segal-Isaacson, EdD, RD

• High Protein DietsHigh Protein Diets

Manny Noakes, PhDManny Noakes, PhD

• Low Fat DietsLow Fat Diets

Keith Ayoob, EdD, RDKeith Ayoob, EdD, RD

Application 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.

Focus of Each Focus of Each Talk:Talk:• Define DietDefine Diet

• Present The Evidence for It’s Present The Evidence for It’s Weight Loss EffectsWeight Loss Effects

• Present The Evidence for Present The Evidence for Cardiovascular and Insulin Cardiovascular and Insulin Sensitivity EffectsSensitivity Effects

• ConclusionsConclusions

Low Carbohydrate Low Carbohydrate Weight Loss DietsWeight Loss Diets

CJ Segal-Isaacson, EdD RDCJ Segal-Isaacson, EdD RDAssistant ProfessorAssistant Professor

Division of Nutrition and Health BehaviorDivision of Nutrition and Health BehaviorDepartment of Epidemiology and Population HealthDepartment of Epidemiology and Population Health

Albert Einstein College of Medicine, Yeshiva UniversityAlbert Einstein College of Medicine, Yeshiva University

Cathy...Cathy...On Low Carbohydrate DietsOn Low Carbohydrate Diets

by Cathy Guisewiteby Cathy Guisewite

Different Strokes For Different Different Strokes For Different FolksFolks

• One size does not fit all with weight loss diets --- One size does not fit all with weight loss diets --- we need a variety of approaches to combat the we need a variety of approaches to combat the obesity epidemic.obesity epidemic.

• It is possible that lower carbohydrate diets may It is possible that lower carbohydrate diets may be more effective for people with Metabolic be more effective for people with Metabolic Syndrome.Syndrome.1-2

1.1. Samaha FF, Iqbal N, Seshadri P, et al. Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. N Engl J Med. May 22 2003; 348 May 22 2003; 348 (21): 2074-2081.(21): 2074-2081.

2.2. Eckel RH, Drazin B. Eckel RH, Drazin B. J. Investigative Med. 51:Suppl. J. Investigative Med. 51:Suppl. 2.2003; S383.2.2003; S383.

Popular Low Carbohydrate Popular Low Carbohydrate DietsDiets

•The Dr. Atkins Diet (Has four levels):The Dr. Atkins Diet (Has four levels):–Induction (<20 g of carbs) Induction (<20 g of carbs) –Ongoing Weight Loss (Typically 25-45 grams carbs)Ongoing Weight Loss (Typically 25-45 grams carbs)–Premaintenance (Typically 30-60 grams carbs)Premaintenance (Typically 30-60 grams carbs)–MMaintenance (Typically 40-100 grams carbs)aintenance (Typically 40-100 grams carbs)

•Carbohydrate Addicts’ DietCarbohydrate Addicts’ Diet

•Protein PowerProtein Power

•Cyclic KetogenicCyclic Ketogenic

•The Zone Diet (30-40-30)The Zone Diet (30-40-30)

•NeanderthinNeanderthin

2001 International2001 International Low Carbohydrate Weight Loss Low Carbohydrate Weight Loss

Survey*Survey*

• Internet-based questionnaire. Internet-based questionnaire.

• Data collected June-July 2001.Data collected June-July 2001.

• 6,088 low carbohydrate dieters 6,088 low carbohydrate dieters responded.responded.

*Segal-Isaacson CJ, Segal-Isaacson AE, Wylie-Rosett, J. *Segal-Isaacson CJ, Segal-Isaacson AE, Wylie-Rosett, J. The JournalThe Journalof The American Dietetic Associationof The American Dietetic Association. 2002. 102: S45.. 2002. 102: S45.

Who Responded To The Survey?Who Responded To The Survey?Questionnaire Was Web-based, With Online Consent

Form

•SAMPLE SIZE: 6,088 “Low Carbers” Responded, June-July 2001

•GENDER: 75.4% Women 24.6% Men

•RACE: 90.5% White 3.5% Hispanic 2.7% Black 3.3% Other

•MAIN GEOGRAPHIC LOCATIONS: 87.5% USA 0.5% Canada

•HIGHEST EDUCATIONAL DEGREE ATTAINED:

0.5% Elementary School

29.4% High School

21.3% Associates Degree

31.5% Bachelors Degree

13.0% Masters Degree

4.4% Doctoral Degree

The Three Most Common Low Carb The Three Most Common Low Carb Diets Diets

2001 Low Carbohydrate Weight Loss Diet 2001 Low Carbohydrate Weight Loss Diet Survey)*Survey)*N= 5177N= 5177

*Segal-Isaacson CJ, Segal-Isaacson AE, Wylie-Rosett, J. The Journal of The American Dietetic Association. 2002. 102: S45.

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

Dr. Atkins Protein Power Carb. Addicts

Typical Macronutrient Profile of Typical Macronutrient Profile of Low Carbohydrate DietsLow Carbohydrate Diets

NutrientNutrient Percentage of CaloriesPercentage of Calories

Carbohydrate:Carbohydrate: 5-25%5-25%

Protein:Protein: 25-35%25-35%

Fat:Fat: 55-65%55-65%

Alcohol:Alcohol: <5% (metabolized mostly as fat)<5% (metabolized mostly as fat)

• Macronutrient percentages may distort what Macronutrient percentages may distort what actually occurs in low carbohydrate dieting.actually occurs in low carbohydrate dieting.

• Due to increased satiety, less food may be Due to increased satiety, less food may be eaten. Carbohydrate intake is reduced while fat eaten. Carbohydrate intake is reduced while fat and protein intake may only moderately and protein intake may only moderately increase. Calories are often substantially increase. Calories are often substantially reduced.reduced.

Typical Low Carbohydrate Typical Low Carbohydrate DinnerDinner

Food Portion Size Calories

Carbs (g)

Fat (g)

Protein (g)

Roast Chicken

1/4 Chicken 306 0 19 31

Green Beans with Sunflower Seeds and Olive Oil

3/4 Cup 102 9 9 3

Green Salad with Italian Dressing

2 Cups with1 Tablespoons

74 4 4 2

Diet Gelatin with Whipped Cream

1 Cup with1 Tablespoon

70 2 6 3

TOTALS : 550 15 38 39

Foods On Low Carbohydrate Foods On Low Carbohydrate DietsDiets

• Unrestricted Foods:Unrestricted Foods: Poultry, fish, meat, Poultry, fish, meat, eggs, protein powders, low-starch vegetables, eggs, protein powders, low-starch vegetables, artificial sweeteners, diet gelatins, oils, butter.artificial sweeteners, diet gelatins, oils, butter.

• Mildly Restricted Foods:Mildly Restricted Foods: Cheeses, tofu, nuts, Cheeses, tofu, nuts, berries, yogurt, milk.berries, yogurt, milk.

• Moderately Restricted Foods:Moderately Restricted Foods: Other fruits, Other fruits, cream, legumes, carbohydrate-reduced soy and cream, legumes, carbohydrate-reduced soy and grain products.grain products.

• Excluded Foods:Excluded Foods: Grains, bread, rice, potatoes, Grains, bread, rice, potatoes, pasta, cereals, candies, pastries, cookies, pies.pasta, cereals, candies, pastries, cookies, pies.

Micronutrient IntakeMicronutrient Intake

• Generally adequate for most Generally adequate for most vitamins and minerals.vitamins and minerals.

• If carbohydrates are severely If carbohydrates are severely restricted (<20 grams):restricted (<20 grams):

– Diet may be low in Vitamin C, Beta Carotene Diet may be low in Vitamin C, Beta Carotene and Fiber.and Fiber.

– Potassium and sodium levels should be Potassium and sodium levels should be monitored and may need to be monitored and may need to be supplemented during the first month of the supplemented during the first month of the diet, as they are additionally excreted in diet, as they are additionally excreted in urine.urine.

Let’s Switch Let’s Switch Gears…..Gears…..

And Talk About Ketogenic, And Talk About Ketogenic,

Very Low Carbohydrate DietsVery Low Carbohydrate Diets

The Role of Ketones The Role of Ketones In Human PhysiologyIn Human Physiology

• Diets containing less than 10-15% Diets containing less than 10-15% carbohydrates usually cause modest carbohydrates usually cause modest amounts of urinary ketosis. amounts of urinary ketosis.

• Ketones are produced as fuel from Ketones are produced as fuel from metabolized fats (acetyl-CoA) when metabolized fats (acetyl-CoA) when carbohydrate-dervived pyruvate is low.carbohydrate-dervived pyruvate is low.

• Enzymes are present within all cells to Enzymes are present within all cells to convert ketones into fuel except in convert ketones into fuel except in erythrocytes, cornea, lens and retina.erythrocytes, cornea, lens and retina.

Adapted from a slide by Eric Westman, MD.Adapted from a slide by Eric Westman, MD.

Serum ketone levels are relatively low Serum ketone levels are relatively low during low carbohydrate diets:during low carbohydrate diets:

–Fed StateFed State 0.1 mmol/L*0.1 mmol/L*

–Overnight FastOvernight Fast 0.3 mmol/L0.3 mmol/L

–Low Carb Ketogenic DietLow Carb Ketogenic Diet 1-3 mmol/L**1-3 mmol/L**

–>20 Days Fasting>20 Days Fasting 10 mmol/L10 mmol/L

–Diabetic KetoacidosisDiabetic Ketoacidosis >25 mmol/L>25 mmol/L

*Meckling et al. Can J Physiol Pharmacol 2002;80:1095-1105.*Meckling et al. Can J Physiol Pharmacol 2002;80:1095-1105.** Sharman MJ et al. J Nutr 2002;132:1879-1885.** Sharman MJ et al. J Nutr 2002;132:1879-1885.

Adapted from a slide by Eric Westman, MD.Adapted from a slide by Eric Westman, MD.

The Role of Ketones The Role of Ketones (continued)(continued)

Short-Term Weight Loss Short-Term Weight Loss StudiesStudies

• Early studies comparing low carb to low fat diets Early studies comparing low carb to low fat diets often used caloric levels of <1000 cal/day. often used caloric levels of <1000 cal/day. These very low calorie studies did not show a These very low calorie studies did not show a weight loss difference between diets.* weight loss difference between diets.*

• Most comparison studies today are using diets Most comparison studies today are using diets with moderate calorie deficits of 500-700 with moderate calorie deficits of 500-700 kcal/day.kcal/day.

• The carbohydrate intake in current studies is The carbohydrate intake in current studies is usually about that of the Atkins “Induction” Diet usually about that of the Atkins “Induction” Diet (most strict level) and is generally (most strict level) and is generally 30 g/day.30 g/day.

*Yang MU, Van Itallie TB. *Yang MU, Van Itallie TB. J Clin Invest. J Clin Invest. Sep 1976;58(3):722-730.Sep 1976;58(3):722-730.

Foster GD, Wyatt HR, Hill JO, et al. Foster GD, Wyatt HR, Hill JO, et al. N Engl J N Engl J Med. Med. May 22, May 22, 22003;348(21): 2082-2090.003;348(21): 2082-2090.

• First published RCT. Six month trial with follow-up First published RCT. Six month trial with follow-up to one year. Average baseline BMI of 34to one year. Average baseline BMI of 34 kg/m kg/m22..

• Atkins Diet (all 4 levels) with ad lib kcal but Atkins Diet (all 4 levels) with ad lib kcal but controlled carbohydrate intake.controlled carbohydrate intake.

• Low cal diet 1200-1500 kcal for women and 1500-Low cal diet 1200-1500 kcal for women and 1500-1800 kcal for men. Energy intake was 60% carb, 1800 kcal for men. Energy intake was 60% carb, 25% fat and 15% protein.25% fat and 15% protein.

• N = 63; 43 women and 20 men. Low carb arm=33 N = 63; 43 women and 20 men. Low carb arm=33 and Low Cal arm=30. Average age is 44 years.and Low Cal arm=30. Average age is 44 years.

• No type 2 diabetes, lipid-lowering meds or other No type 2 diabetes, lipid-lowering meds or other serious illness. serious illness.

Weight Loss Results of Foster et al. Weight Loss Results of Foster et al.

• Better participant retention in low carb arm at all Better participant retention in low carb arm at all measurement points -- 3,6 & 12 months, p<0.05.measurement points -- 3,6 & 12 months, p<0.05.

• Did not report on actual calorie intakes of Did not report on actual calorie intakes of subjects.subjects.

• Weight loss significantly better in low carb group Weight loss significantly better in low carb group at 3 and 6 months but not at 12 months:at 3 and 6 months but not at 12 months:

3 Month Wt Loss: 3 Month Wt Loss: Low Carb -6.8 ±5.0% Low Cal -2.7 ± 3.7% (p<0.001).Low Carb -6.8 ±5.0% Low Cal -2.7 ± 3.7% (p<0.001).

6 Month Wt Loss: 6 Month Wt Loss: Low Carb -7.0 ± 6.5% Low Cal -3.2 ± 5.6% (p<0.02).Low Carb -7.0 ± 6.5% Low Cal -3.2 ± 5.6% (p<0.02).

12 Month Wt Loss: 12 Month Wt Loss: Low Carb -4.4 ± 6.7% Low Cal -2.5 ± 6.3% (p<0.26).Low Carb -4.4 ± 6.7% Low Cal -2.5 ± 6.3% (p<0.26).

Weight Loss Results of Foster et al.Weight Loss Results of Foster et al.

From p. 2085 of Foster et al., 2003 NEJM.

Lipid Results of Foster et al.Lipid Results of Foster et al.

From p. 2088 of Foster et al., 2003 NEJM.

Blood Pressure and Blood Pressure and Insulin Sensitivity Insulin Sensitivity

Results of Foster et al.Results of Foster et al.

Equivalent improvements for both Equivalent improvements for both groups at 3,6 and 12 months for:groups at 3,6 and 12 months for:

•Systolic and diastolic blood pressure.Systolic and diastolic blood pressure.

•Area under the glucose curve (OGT).Area under the glucose curve (OGT).

•Area under the insulin curve (OGT).Area under the insulin curve (OGT).

•Insulin sensitivity. Insulin sensitivity.

Summary Of Results From Short-Term Summary Of Results From Short-Term StudiesStudies

• Low carb diets consistently produced more Low carb diets consistently produced more weight loss in RCTs that did not control the weight loss in RCTs that did not control the calorie levels between diets.calorie levels between diets.

1.1. Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DA. Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DA. J Clin Endocrinol J Clin Endocrinol Metab. Metab. Apr 2003;88(4):1617-1623.Apr 2003;88(4):1617-1623.

2.2. Foster GD, Wyatt HR, Hill JO, et al. Foster GD, Wyatt HR, Hill JO, et al. N Engl J Med. N Engl J Med. May 22, May 22, 22003;348(21): 2082-2090.003;348(21): 2082-2090.

3.3. Samaha FF, Iqbal N, Seshadri P, et al. Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. N Engl J Med. May 22 May 22 2003;348(21):2074-2081.2003;348(21):2074-2081.

4.4. Westman EC, Yancy WS, Guyton JS. Westman EC, Yancy WS, Guyton JS. AHA. Nutrition Abstracts. AHA. Nutrition Abstracts. Circulation (Supplement II). Circulation (Supplement II). 2002;106(19).2002;106(19).

Summary Of Results From Short-Term Summary Of Results From Short-Term Studies cont.Studies cont.

• In a recent study where the calories were kept the In a recent study where the calories were kept the same, the weight loss was fairly comparable same, the weight loss was fairly comparable between the Atkins Diet and the DASH Diet between the Atkins Diet and the DASH Diet although there was a trend for greater weight loss although there was a trend for greater weight loss by 1.3 kg in the Atkins group. by 1.3 kg in the Atkins group.

• Due to the small sample size in each group (n=13) Due to the small sample size in each group (n=13) in the Atkins group and (n=12) in the DASH group, in the Atkins group and (n=12) in the DASH group, and the short time the results are not definitive. and the short time the results are not definitive.

1.1. Stadler D, Burden V, McMurry M, Gerhard G, Connor W, Karanja N. Stadler D, Burden V, McMurry M, Gerhard G, Connor W, Karanja N. Presentation at Experimental Biology annual conference, April, 2003.Presentation at Experimental Biology annual conference, April, 2003.

• Current RCT trials at the Albert Einstein College of Current RCT trials at the Albert Einstein College of Medicine and Harvard University are also trying to Medicine and Harvard University are also trying to answer the question of diet composition per se answer the question of diet composition per se affects weight loss rates.affects weight loss rates.

Summary Of Results From Short-Term Summary Of Results From Short-Term Studies cont.Studies cont.

• Low carbohydrate diets may produce more Low carbohydrate diets may produce more satiety and reduced appetite …. leading to satiety and reduced appetite …. leading to decreased caloric intake. decreased caloric intake.

• Increased satiety may explain generally lower Increased satiety may explain generally lower drop-out rates in low carbohydrate groups. If drop-out rates in low carbohydrate groups. If there is increased satiety, is it due to protein?there is increased satiety, is it due to protein?

1.1. Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DA. Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DA. J Clin Endocrinol J Clin Endocrinol Metab. Metab. Apr 2003;88(4):1617-1623.Apr 2003;88(4):1617-1623.

2.2. Foster GD, Wyatt HR, Hill JO, et al. Foster GD, Wyatt HR, Hill JO, et al. N Engl J Med. N Engl J Med. May 22, May 22, 22003;348(21): 2082-2090.003;348(21): 2082-2090.

3.3. Samaha FF, Iqbal N, Seshadri P, et al. Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. N Engl J Med. May 22 May 22 2003;348(21):2074-2081.2003;348(21):2074-2081.

4.4. Westman EC, Yancy WS, Guyton JS. Westman EC, Yancy WS, Guyton JS. AHA. Nutrition AHA. Nutrition Abstracts. Abstracts. Circulation (Supplement II). Circulation (Supplement II). 2002;106(19).2002;106(19).

Summary Of Results From Short-Term Summary Of Results From Short-Term Studies cont.Studies cont.

• A low carbohydrate weight loss diet produced a A low carbohydrate weight loss diet produced a greater reduction than a low fat weight loss greater reduction than a low fat weight loss diet in the inflammatory markers C-reactive diet in the inflammatory markers C-reactive protein and serum amyloid A. Both markers are protein and serum amyloid A. Both markers are associated with cardiovascular risk. associated with cardiovascular risk.

• Unclear whether the better reduction in Unclear whether the better reduction in inflammatory markers with the low carb diet inflammatory markers with the low carb diet was related to greater weight loss in the low was related to greater weight loss in the low carb group or was independent of this effect. carb group or was independent of this effect.

1.1. O’Brien KD, Brehm BJ, Seeley RJ, Werner M, Daneils, D,D’Alessio O’Brien KD, Brehm BJ, Seeley RJ, Werner M, Daneils, D,D’Alessio DA. DA. AHA. Nutrition Abstracts. AHA. Nutrition Abstracts. Circulation .(Supplement II). Circulation .(Supplement II). 2002;106(19).2002;106(19).

Summary Of Results From Short-Term Summary Of Results From Short-Term Studies cont.Studies cont.

• Preliminary evidence from 1 month study Preliminary evidence from 1 month study showed greater urinary acid and calcium showed greater urinary acid and calcium excretion among overweight volunteers (BMI = excretion among overweight volunteers (BMI = 29.4 kg/m29.4 kg/m2) 2) on a very low carbohydrate diet on a very low carbohydrate diet compared to their normal diet. compared to their normal diet.

• Study found no metabolic acidosis. It did find Study found no metabolic acidosis. It did find increased urinary acid excretion that was due increased urinary acid excretion that was due to the increase in sulfur-containing amino acids to the increase in sulfur-containing amino acids from protein foods and acidic ketone bodies. from protein foods and acidic ketone bodies. This may increase the risk of renal stones.This may increase the risk of renal stones.

1.1. Reddy ST, Wang CY, Sakhaee K, Brinkley L, Pak CY. Reddy ST, Wang CY, Sakhaee K, Brinkley L, Pak CY. Am J Kidney Dis. Am J Kidney Dis. Aug 2002;40(2):265-274.Aug 2002;40(2):265-274.

Summary Of Results From Short-Term Summary Of Results From Short-Term Studies cont.Studies cont.

• Increased calcium excretion without Increased calcium excretion without compensatory increase in intestinal calcium compensatory increase in intestinal calcium absorption may lead to bone loss.absorption may lead to bone loss.

• However, it’s unclear whether if a low carb diet However, it’s unclear whether if a low carb diet was used for a longer time period, whether was used for a longer time period, whether there might be physiological adaptation to it. there might be physiological adaptation to it. Longer term studies are needed.Longer term studies are needed.

• Do populations such as the Eskimos who have Do populations such as the Eskimos who have survived on very low carb diets show such survived on very low carb diets show such adaptations?adaptations?

1.1. Reddy ST, Wang CY, Sakhaee K, Brinkley L, Pak CY. Reddy ST, Wang CY, Sakhaee K, Brinkley L, Pak CY. Am J Kidney Dis. Am J Kidney Dis. Aug 2002;40(2):265-274.Aug 2002;40(2):265-274.

Summary Of Results From Short-Term Summary Of Results From Short-Term Studies cont.Studies cont.

• Low Carbohydrate Weight Loss Diets may work Low Carbohydrate Weight Loss Diets may work better for people with Metabolic Syndrome -- better for people with Metabolic Syndrome -- better weight loss, and greater improvements better weight loss, and greater improvements in triglyceride levels. Better weight loss tracks in triglyceride levels. Better weight loss tracks with insulin sensitivity improvements.with insulin sensitivity improvements.

• Insulin sensitive participants lost more weight Insulin sensitive participants lost more weight on the LF/HC diet compared to the HC/LC diet on the LF/HC diet compared to the HC/LC diet (13.56 ± 1.60 kg compared to 6.12 ± 1.13 kg, (13.56 ± 1.60 kg compared to 6.12 ± 1.13 kg, p<0.01). Also there was a trend for p<0.01). Also there was a trend for improvements in insulin sensitvity in already IS improvements in insulin sensitvity in already IS participants on the LF/HC diet. participants on the LF/HC diet.

Summary Of Results From Short-Term Summary Of Results From Short-Term Studies cont.Studies cont.

• Insulin resistant participants lost more weight Insulin resistant participants lost more weight on the HF/LC diet compared to the LF/HC diet on the HF/LC diet compared to the LF/HC diet (11.46 ± 1.37 kg compared to 6.52 ± 0.98 kg, (11.46 ± 1.37 kg compared to 6.52 ± 0.98 kg, p<0.05). Also there was a trend for p<0.05). Also there was a trend for improvements in insulin sensitvity in insulin improvements in insulin sensitvity in insulin resistant participants on the HF/LC diet. resistant participants on the HF/LC diet.

1.1. Samaha FF, Iqbal N, Seshadri P, et al. Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. N Engl J Med. May 22 May 22 2003;348(21):2074-2081.2003;348(21):2074-2081.

2.2. Eckel RH, Drazin B. Eckel RH, Drazin B. J. Investigative Med. 51:SupplJ. Investigative Med. 51:Suppl 2.2003; S383. 2.2003; S383.

Summary Of Results From 2001 Low Summary Of Results From 2001 Low Carbohydrate Weight Loss Survey,Carbohydrate Weight Loss Survey,

N=6,088N=6,088

Segal-Isaacson CJ, Segal-Isaacson AE, Wylie-Rosett, J. Segal-Isaacson CJ, Segal-Isaacson AE, Wylie-Rosett, J. The The Journal of The American Dietetic AssociationJournal of The American Dietetic Association. 2002. 102: . 2002. 102:

S45.S45.

• More than half of the respondents (55.9%) were More than half of the respondents (55.9%) were currently dieting to lose weight and their BMI was currently dieting to lose weight and their BMI was higher than those who were not trying (31.2 higher than those who were not trying (31.2 7.8 7.8 compared to 29.8 compared to 29.8 7.6; p < 0.001). 7.6; p < 0.001).

• Those who were not currently dieting to lose weight Those who were not currently dieting to lose weight reported they had lost an average of 36.2 reported they had lost an average of 36.2 25.6 lbs 25.6 lbs but had wanted to lose 56.3 but had wanted to lose 56.3 41.3 lbs. 41.3 lbs.

• The amount of weight these respondents reported The amount of weight these respondents reported they kept off for at least one year was at least 11-20 they kept off for at least one year was at least 11-20 lbs for 53.2% of the respondents and at least 21-30 lbs for 53.2% of the respondents and at least 21-30 lbs for 37.4% of the respondents. lbs for 37.4% of the respondents.

Summary Of Results From 2001 Low Summary Of Results From 2001 Low Carbohydrate Weight Loss SurveyCarbohydrate Weight Loss Survey

cont.cont.

• Most respondents modified the diet they chose Most respondents modified the diet they chose (60.2%). The most common modifications were (60.2%). The most common modifications were adding more vegetables (29.0%), fruit (12.4%) or adding more vegetables (29.0%), fruit (12.4%) or occasionally going off the diet (32.7%).occasionally going off the diet (32.7%).

• The three most common diet likes were not feeling The three most common diet likes were not feeling hungry (87.5%) or deprived (85.6%) and losing weight hungry (87.5%) or deprived (85.6%) and losing weight easily (74.1%). easily (74.1%).

• The three most common diet dislikes were bad breath The three most common diet dislikes were bad breath (30.9%), light headedness (15.0%) and nausea (30.9%), light headedness (15.0%) and nausea (8.3%). (8.3%).

Current Low Carbohydrate Research Current Low Carbohydrate Research At The Albert Einstein College of At The Albert Einstein College of

Medicine Medicine

• The CCARB StudyThe CCARB Study: First long-term study on low : First long-term study on low carbohydrate dieters. Internet-based -- will follow each carbohydrate dieters. Internet-based -- will follow each participant for at least three years. More than 50% of participant for at least three years. More than 50% of participants have objectively documented their weight participants have objectively documented their weight and height through their healthcare provider. Will also and height through their healthcare provider. Will also assess lipid values in a subset. Website address is: assess lipid values in a subset. Website address is: http://epi.aecom.yu.edu/ccarbshttp://epi.aecom.yu.edu/ccarbs

• The Metabolic Impact StudyThe Metabolic Impact Study: Pilot controlled feeding study : Pilot controlled feeding study that uses isocaloric-isonitrogenous diets to determine that uses isocaloric-isonitrogenous diets to determine whether a very low carbohydrate diet burns body fat more whether a very low carbohydrate diet burns body fat more quickly than a moderate low fat diet. Uses stable isotopes quickly than a moderate low fat diet. Uses stable isotopes to trace whether ingested fats are oxidized or stored; to trace whether ingested fats are oxidized or stored; indirect calorimetry to measure energy expenditure and indirect calorimetry to measure energy expenditure and and MRI to measure body fat distribution. and MRI to measure body fat distribution.

Current Low Carbohydrate Research Current Low Carbohydrate Research At The Albert Einstein College of At The Albert Einstein College of

Medicine cont.Medicine cont.

• The Diabetes Dietary StudyThe Diabetes Dietary Study: Study on 74 adults : Study on 74 adults with type 2 diabetes who also take insulin. Study with type 2 diabetes who also take insulin. Study will compare a one year trial of an Atkins-style low will compare a one year trial of an Atkins-style low carbohydrate diet to the low fat diet used in the carbohydrate diet to the low fat diet used in the Diabetes Prevention Project. Diabetes Prevention Project.

• Call 718 430-2161 for more information on any of Call 718 430-2161 for more information on any of the three studies or email at the three studies or email at isaacson@aecom.yu.edu .isaacson@aecom.yu.edu .

Annotated Annotated BibliographyBibliography

Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DA. J Clin Endocrinol Metab. Apr 2003;88(4):1617-1623.

• Six month RCT with 53 obese women comparing a low carb (<20 g/day for first two weeks then 40-60 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.

Eckel RH, Drazin B. J. Investigative Med.51:Suppl2.2003; 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 ± 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.

Eckel RH, Drazin B. J. Investigative Med.51:Suppl2.2003; 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 ± 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.

• 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.

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.

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.

Reddy ST, Wang CY, Sakhaee K, Brinkley L, Pak CY.Am J Kidney Dis. Aug 2002;40(2):265-274.

• 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.

Reddy ST, Wang CY, Sakhaee K, Brinkley L, Pak CY.Am J Kidney Dis. Aug 2002;40(2):265-274. 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.

Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. May22 2003;348(21):2074-2081.

• 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.

Samaha FF, Iqbal N, Seshadri P, et al. N Engl J Med. May22 2003;348(21):2074-2081. 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).

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.

Westman EC, Yancy WS, Edman JS, Tomlin KF, PerkinsCE. 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.

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.

Health Sciences and Nutrition

Popular Weight Loss Diets: Popular Weight Loss Diets: What’s The Evidence?What’s The Evidence?

Moderately High Protein Lower Carbohydrate(30% protein; <30% fat; 40% carbohydrate)

Dr Manny NoakesSenior Research Dietitian

CSIRO Clinical Research UnitAustralia

Rationale for Moderately High Protein Intakes in Weight Loss?

Emerging scientific evidence for effects on satiety

Dietary pattern that is nutritionally adequate

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)

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 plans– Atkins 43%, – Zone 60%, – Conventional 36% Landers P J Okla State Med Assoc. 2002

Protein vs Carbohydrate in ad libitum Fat Reduced Diet

Skov et al 1999

High-carbohydrate(HC, protein 12% energy) n=25

High-protein (HP, protein 25% energy) n=25

RESULTS AFTER 6 MONTHS 5.1 kg in the HC group 8.9 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.

Increased Protein/Carb ratioin overweight women

Layman et al J Nutr. 2003

CHO/protein ratio3.5 (CHO Group)

68g protein1.4 (Protein group)

125g protein

Increased Protein/Carb ratioin overweight women

Layman et al J Nutr. 2003

CHO/protein ratio3.5 (CHO Group)

68g protein1.4 (Protein group)

125g protein

Weight Loss Maintenance

0 4 8 12 0 4 8 12

HPHP

Weight Loss MaintenanceLP

Interventions:Interventions: Fat <30%, sat fat <10% 6500kJ Fat <30%, sat fat <10% 6500kJ

High Protein (HP) - 28% E Protein, 42% E CHOHigh Protein (HP) - 28% E Protein, 42% E CHO

Low Protein (LP) - 16% E Protein, 55% E CHOLow Protein (LP) - 16% E Protein, 55% E CHOParker B, Noakes M, Luscombe N, Clifton P.Diabetes Care. 2002

Foods HP diet LP dietWeetbix 1 1

Milk - 1% fat 250ml 250ml

Skim milk powder 30g -

Fruit Yoghurt - 0.1% fat 200g (7oz) -

Wholemeal bread 2 sl 3 sl

Fruit 2 small 3 small

Meat/fish/chicken 200g (7oz) 100g (3.5oz)

Low kJ Vegetables <2.5 cups <2.5 cups

Cheese - 3% fat 60g (2oz) -

Rice - 1 cup cooked

Canola lite margarine 2 tsp 3 tsp

Sunola oil 3 tsp 3 tsp

Shortbread biscuits 3 4

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

High Protein Diets and Renal Function in D2

Urinary albumin excretion was not affected by dietary protein during weight loss:

n=19 with microalbuminuria

HP 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

1

1.2

1.4

1.6

1.8

2

0 4 8 12 16

Week

Tri

glyc

erid

es (

mM

ol/L

)

High carb

HighProtein

Diet effect p < 0.05

High Protein Diets InSubjects With High Insulin

9.6%

22.8%

Farnsworth et al AJCN 2003

0

20

40

60

80

100

120

140

0 30 60 120 180

Time (min)

Insu

lin

(m

U/l

)

High Protein

High Carb

Insulin Response to Test Meals

Diet effect p < 0.05

Farnsworth et al AJCN 2003

4

5

6

7

8

9

0 30 60 120 180

Time (min)

Glu

cose

(m

Mol

/l)

High Protein

High carb

Glucose Response to Test Meals

Diet effect p = 0.020

Farnsworth et al AJCN 2003

To compare a high protein weight loss diet with a high carbohydrate diet on

weight loss and body

composition nutrient status bone turnover markers measures of heart disease risk in women over 12

weeks… ..and subsequently follow up for 1 year

Diets:

1. High carbohydrate

2. High protein, high red meat

Aim:

High Meat Protein 5600 KJ (1330 kcal)

• Cereal• Low fat milk (250ml) 8oz• Wholemeal bread (2 slices)• Fruit (2)• Beef/lamb 200g (7oz)- • dinner• Chicken/fish/meat 100g (3.5oz)

lunch• Vegetables 2.5 cups• Diet Yoghurt 200g (7oz)• Canola oil 3 tsp• Wine 2 glasses/week (optional)

34% protein20% fat46% carbohydrate

109g protein 31g fat 161g carbohydrate

• Cereal

• SKIM milk (250ml) 8oz

• Wholemeal bread (3 slices)

• Fruit (3)

• Chicken/pork/fish 80g - 3oz

• Vegetables 2.5 cups

• Canola oil 3 tsp

• Pasta/rice 120g/4oz cooked

• Low fat biscuits 3

• Wine 2 glasses/week (optional)

High Carbohydrate 5600 KJ (1330 kcal)

17% protein20% fat64% carbohydrate

57g protein 31g fat 229 g carbohydrate

Baseline characteristics by TG Status

LOW TG HIGH TG

TREAT HP HC HP HC

Mean Mean Mean Mean

AGE 49.3 45.5 49.8 52.4

BMI 32.8 33.0 31.8 32.9

WEIGHT 89.1 86.5 85.2 86.4

Triglycerides 0.9 0.9 1.9 2.0

Weight Loss by Triglyceride Status

•Sig diet effect P=0.023

High protein

High carb

7.37.88.0

5.9

3.0

4.0

5.0

6.0

7.0

8.0

9.0

Low TG High TG

wei

gh

t lo

ss (

kg)

5.135.86

6.28

3.63

0

2

4

6

8

high protein -low TG

highcarbohydrate-

low TG

high protein -high TG

highcarbohydrate-

high TG

kgTotal And Midriff Fat Loss

Dexa Data

* Sig diet effect

High protein

High carb

Triglycerides by TG status

0

0.5

1

1.5

2

2.5

week 0 week 4 week 8 week 12

TG m

mol

/L

HIGH TG

LOW TG

10%

28%

Diet X TG interaction P=0.01

CRP

0

2

4

6

8

10

12

14

week 0 week 12

CR

P m

g/L

high protein

high carb

(Effect of diet P=0.07, with overall ANOVA p=0.019) after accounting for TG status

Total T3

1.6

1.8

2

2.2

2.4

2.6

week 0 week 12

pm

ol/L high protein

high carb

Significant effect of diet P=0.005 suggesting lower energy intake on high protein diet

TREAT

21

Me

an

4.6

4.4

4.2

4.0

3.8

3.6

3.4

3.2

3.0

2.8

calciumv1

calciumv4

Cal

cium

exc

retio

n m

mol

/24h

r

High protein High carb

week 0

week12

reference range 2.5-7.5mmol/24hr

Calcium ExcretionCalcium excretion decreased on both diets

There 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 diabetes

Subjects with elevated insulin levels

CONCLUSION

There 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

Popular Weight Loss Diets: What’s the Evidence?

Low-fat and Very Low-fat Diets

Keith-Thomas Ayoob, EdD, RD, FADA

Albert Einstein College of Medicine

July 17, 2003

Macronutrient distribution

• American Heart Association-style– < 30% fat– 15% protein– 55% CHO

• Very low-fat diet– 10-15% fat– 12-15% protein– 72-75% CHO

Typical dinner--AHA-style

3-oz. Broiled salmon

2/3 cup rice

1/2 cup mixed vegetables

1 cup salad greens, 2 tsp. Vinaigrette

1 slice whole wheat bread

1 tsp. butter

1/4 cantaloupe

Typical dinner--very low-fat

• 3-oz. baked whitefish• 1-1/2 cups sauteed

collard greens• baked sweet potato• 1/2 cup wild rice pilaf• baked apple

Low-fat Diets: Weight Loss

• 2003 review by Pirozzo, et al• Criteria for inclusion

– Randomized Ccontrolled Trial (RCT) of Low- Fat vs. other wt loss diets

– primary purpose was wt. Loss– Age > 18 years & BMI > 25 at baseline– Followed for at least 6 months– “Low fat diet” = < 30% of calories from fat

Pirozzo, S. et al. Cochrane Database of Systematic Reviews. 1, 2003.

Low-fat Diets: Weight Loss

• Four 6-months studies

• Five 12-month studies

• Three 18-months studies

Result:

• No significant differences compared to other weight loss diets

Low-fat Diets: Weight Loss

• Meta-analysis of 34 studies,

• 2-12 months duration

• ad lib low-fat diets vs. controls

• Result:– 3.3 kg loss in low-fat groups (sig.)

• Main factors:– degree of dietary fat reduction

– pre-treatment body weightAstrup A, et al. Int J Obes Relat Met Dis. 2000 Dec; 24(12):1545

Low-fat Diets: Long-term Success

• Review by Ayyad & Anderson, 2000• Criteria for inclusion:

– adults– Follow up of > 3 years– Follow up of > 50% of original study group

• Criteria for long-term success: – Maintain > 9-11 kg or all weight initially lost

Ayyad C and Anderson T. Obesity Reviews, 2000; 1:113-9

Low-fat Diets: Long-term Success

• Overall, 15% of followed-up subjects met criteria for success– Diet alone = 15% met follow-up success – Diet + group therapy = 27% met success – Diet & behavior mod. = 14% met success

• Active follow-up better than passive for long term success (19% vs. 10%)

Low-fat diets vs. moderate/high-fat diets

• 12 month duration

• 4 DIETS: – low-fat(LF)

– moderate fat(MF)

– mod fat-isocaloric(MF-iso)

– high fat(HF)

• weight, lipids, CV riskFleming, RM. Preventive Cardiology. 5(3):110, 2002

RESULTS: Low-fat vs moderate & high-fat diets

-18%-16%-14%-12%-10%-8%-6%-4%-2%0%

1st Qtr

LFMFHFMF-iso

% body weight lost at 12 months

Wt loss associated with calories ONLY

NS

Low-fat diets and satiety

• Review of low-energy diets, glycemic index (GI), and obesity– Low-GI foods = Increased satiety – low-fat, low-GI-based diets = promote satiety

and may therefore promote weight loss – high-GI diets = weight gain and lower satiety

• Similar in animal studies

Brand-Miller et al. Am J Clin Nutr. 76(1):281S, 2002 July

Long-term Compliance/Maintenance

• McGuire et al– random digit phone survey– maintainers = lost > 10% of wt. , maintained for

> 1 yr.

• 69 Maintainers, 56 regainers, 113 wt-stable controls

McGuire et al. Int J of Ob & Rel Metab Disord: J of the Int Assoc Study of Ob. 23(12):1314, 1999 Dec

Long-term Compliance/Maintenance

Common factors for success:

• lower-fat intake than regainers/controls

• behavior strategies used more than regainers

• more physically active, esp. strenuous activity

National Weight Control Registry

• Maintained a loss of > 25 lb. for > 1 year

• lost weight by different methods

• Maintainers:– low fat, modest calorie

intake

– Physically active 4-5 days/week

LF Diets and Drop-outs

• Problem in many studies– Most studies are 6 months or less– Only count those who completed study

• Longer studies self-select

• Several studies do show compliance after 1 year

• Drop-out rate: 11-40% (Pirozzi, et al)

Lipids & low-fat diets

• Low calorie AND low/moderate fat:– significantly lower cholesterol, LDL-chol, TGs,

TC/HDL ratios

• Low-calorie, high-fat diets, OR mod fat, isocaloric diets– no significant changes:TG, TC, HDL, LDL-

chol

Fleming, RM. Preventive Cardiology. 5(3):110, 2002

C-reactive protein (CRP) & low-fat diets

• CRP strongly associated with BMI

• LF diet (15% fat, 62% CHO) -- 12 wks

• CRP significantly with Low-Fat/low-

calorie diet and wt loss

• Other dietary composition not investigatedHeilbron et al. Arterioscl, Thromb & Vasc Biol. 21(6):968, 2001 June

LDL & low-fat diets

• 2001 review by Krauss• LDL-A = desirable large, fluffy LDL• LDL-B = small, dense LDL (atherogenic)• Conclusion:

– genes play a role– LDL-B: benefits from a low-fat diet– LDL-A: no benefits from low-fat diet IF isocaloric, &

may convert to LDL-B profile– CAVEAT: studies are often short-term, not all hi-CHO

diets are alike

Krauss. J of Nutr. 131(2) 340S; 2001 Feb

HDL & low-fat diets

• Meta-analysis of studies > 2months• LF diet lowered HDL, less so when fed ad

lib than isoenergetically• Epi studies consistently show populations

with LF diets and low-HDL have LOW atherosclerosis

• Diets high in fruits, vegetables and grain fiber promote less atherosclerosis, cancer

Jequier E and Bray G. Am J of Med. 113(9) supp. 2:41 2002 Dec

Effect of type and amount of fat on HDL/lipids

• Meta-analysis of 60 studies, Mensink et al

• Conclusion:– Replacing fat with CHO isoenergetically may increase

total/HDL ratio– Replacing fat with CHO and reducing calories could

have same effect as replacing SFA with MUFA and PUFA

– Replacing trans-fat with MUFA/PUFA had best effect on blood lipids

– Caveat: Results are general but the need is individual

Mensink, RP et al. AM J Clin Nutr. 77(5); 1146, 2003 May

LF diets and insulin

• Review by Brand-Miller, et al– Low-fat, hi-CHO, hi-GI diets may increase

insulin response– BUT low-fat, low glycemic diets may promote

wt loss via increased satiety, lowered insulin response

• Exercise improves insulin response

Brand-Miller et al. Am J Clin Nutr. 76(1):281S, 2002 July

CONCLUSIONS

• Calories count more than fat: Low energy diets are more effective at producing weight loss than low-fat diets

• BUT low-fat diets may make it easier to reduce total energy intake

CONCLUSIONS

• Risks of Low-fat diets– Difficult long-term compliance on very low-fat diet

• increases with close follow-up and group support

– type of CHO may affect outcome, possibly by altering satiety

• Benefits– Strong association with long-term maintenance– LF, hi-CHO, hi-fiber diet reduces other health risks and

is usually rich in vitamins, minerals, and phytonutrients

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?