The Atkins Diet

1
The Atkins Diet

• Cristi Howe, M. D.

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Obesity

• Excess body fat relative to lean body mass
• Associated with obstructive sleep apnea,
  hypertension, cardiovascular disease, stroke,
  diabetes, osteoarthritis, death
• 325,000 deaths/year
• 39 - 52 billion/year
• Measured by Body Mass Index (BMI)
• BMI weight (kg)/height2 (m2)
• Healthy 18.5 24.9
• Overweight 25 29.9
• Obese 30
• Between 1991-2001, the prevalence of obese U. S.
  adults has increased from 12 to 21.
• Currently, 44 million U. S. adults are obese.

3
Obesity Trends Among U.S. AdultsBRFSS, 1985
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
4
Obesity Trends Among U.S. AdultsBRFSS, 1986
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
5
Obesity Trends Among U.S. AdultsBRFSS, 1987
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
6
Obesity Trends Among U.S. AdultsBRFSS, 1988
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
7
Obesity Trends Among U.S. AdultsBRFSS, 1989
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
8
Obesity Trends Among U.S. AdultsBRFSS, 1990
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
9
Obesity Trends Among U.S. AdultsBRFSS, 1991
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
10
Obesity Trends Among U.S. AdultsBRFSS, 1992
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
11
Obesity Trends Among U.S. AdultsBRFSS, 1993
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
12
Obesity Trends Among U.S. AdultsBRFSS, 1994
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
13
Obesity Trends Among U.S. AdultsBRFSS, 1995
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
14
Obesity Trends Among U.S. AdultsBRFSS, 1996
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
15
Obesity Trends Among U.S. AdultsBRFSS, 1997
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
16
Obesity Trends Among U.S. AdultsBRFSS, 1998
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
17
Obesity Trends Among U.S. AdultsBRFSS, 1999
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
18
Obesity Trends Among U.S. AdultsBRFSS, 2000
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
19
Obesity Trends Among U.S. AdultsBRFSS, 2001
Source Mokdad A H, et al. J Am Med Assoc
199928216, 200128610.
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Case

• 55 year old female with PMH of hypertension and
  hyperlipidemia. She does have a family history
  of premature heart disease and uses tobacco.
  Over the past year she has developed progressive
  weight gain. Her BMI is currently 32. Recently,
  she has exhibited mild glucose intolerance with
  fasting sugars between 115 120. You suggest
  that she needs to lose weight to prevent the
  onset of diabetes.....
  ..She asks HOW?

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Law of Thermodynamics

• The energy of an isolated system is constant and
  any exchange of energy between a system and its
  surroundings must occur without the creation or
  destruction of energy.
• Calories units of energy
• Carbohydrate 4 kcal/gram
• Protein 4 kcal/gram
• Fat 9 kcal/gram
• Weight loss results from decreased caloric intake
  and increased caloric expenditure.
• 3500 kcal 1 pound

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U.S. Department of Agriculture
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American Heart Association

• Calories
• Weight Maintenance Weight (lbs) 15 (2300
  calories)
• Carbohydrate
• 50 60 caloric intake (345 g)
• Limit simple carbohydrates, 20-30 g/day fiber
• Protein
• 10 - 20 caloric intake (58 g)
• Fat
• lt 30 caloric intake (76 g)
• 10 unsaturated, 10 polyunsaturated, lt10
  saturated
• Cholesterol lt 300 mg/day

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• You stopped eating red meat, cooked
  egg-white-only omelettes with no shortening in a
  Teflon pan, removed the skin from chicken, ate
  your baked potato without butter or sour cream
  and consumed lots of pasta. Frozen yogurt,
  fruit, and sherbert served as dessert. Your
  breakfast consisted of oatmeal and skim milk or
  else granola and a banana. A typical lunch was
  white-meat turkey on a roll and a generous salad,
  hold the dressing.

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The Atkins Diet

• Low-carbohydrate
• High-fat
• High-protein
• NO caloric restriction

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The Atkins Diet

• It is the most successful weight loss and weight
  maintenance program of the last quarter of the
  twentieth century. It works an astonishing
  proportion of the time for the vast majority of
  men and women.
• It can positively impact the lives of people
  facing the risks of diabetes, heart disease, and
  hypertension.

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Prevalence of Overweight U. S. Adults
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Physiology of Metabolism
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Physiology of Metabolism
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Physiology of Metabolism
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Physiology of Metabolism
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Physiology of Metabolism
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The Atkins Diet

• Avoids glucose surges and insulin release
• Avoids anabolic processes that produce
  glycogen and fat
• Prevents reactive hypoglycemia
• Curtails insulin resistance
• Improves blood pressure
• Decreases triglycerides

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The Atkins Diet

• Stimulates glucagon and catabolic processes
• Glycogenlysis
• Gluconeogenesis
• Fat breakdown
• Ketones serve as the primary source of energy
• Ketosis produces anorexic effect
• Fat stimulates cholecystokinin and
  delayed gastric emptying creating satiety

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CriticsAmerican Diabetic AssociationAmerican
Heart Association

• Ketone accumulation
• Abnormal insulin metabolism
• Impaired kidney function
• Postural hypotension
• Fatigue
• Constipation
• Nephrolithiasis
• Hyperlipidemia

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The Atkins Diet

• Pre-evaluation
• Blood pressure
• Complete metabolic profile, uric acid, TSH
• Glucose tolerance test with associated insulin
  levels
• Medications
• Diuretics
• Antihypertensives
• Diabetes medications
• Contraindications
• Pregnancy, Renal failure (Cr gt 2.4)

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The Atkins Diet

• Induction
• Eat liberal amounts of calories every six hours
  until satiated
• Limit daily carbohydrate intake to lt 20 grams
• 3 cups of salad vegetables
• 2 cups of salad 1 cup of acceptable
  vegetables
• NO fruit, bread, pasta, grains, starchy
  vegetables, nuts, dairy
• (except cheese, butter, cream)
• No alcohol, caffeine, or aspartame
• 64 ounces of water/day
• Multivitamin supplementation

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The Atkins Diet

• Induction
• 2 week period to stimulate ketosis
• 6 - 10 pound weight loss over two weeks
• Water loss over the first 7 10 days
• Fatigue and withdrawal symptoms over 1st few days
• Constipation secondary to low fiber intake

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The Atkins Diet

• Ongoing Weight Loss
• Increase daily carbohydrate intake 5 grams/week
  until you reach critical carbohydrate level of
  losing
• Only low glycemic index food allowed (Glucose
  100)
• Once you reach CCLL decrease
  daily carbohydrate intake by 5 gram
• Continue until 5 10 pounds shy of goal weight

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The Atkins Diet

• Pre-maintenance
• Increase daily carbohydrate intake by 10
  grams/week until goal weight
• Maintain carbohydrate level for one month
• Increase carbohydrate level until weight gain
• Then decrease slightly to critical carbohydrate
  level of maintenance (CCLM)

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The Atkins Diet

• Lifetime Maintenance
• Maintain CCLM
• Average metabolic resistance 40 60 grams/day
• Regular exerciser gt90 grams/day
• Allow a 5 pound weight variation
• If weight exceeds the upper limit, return to
  induction

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Early Studies

• 1863 Banting Diet
• 1953 Pennington
• Treatment of Obesity with
• Calorically Unrestricted Diets
• Limit carbohydrate intake to lt 60 grams/day
• Avoid production of pyruvic acid
• Prevents fat synthesis
• Stimulates fat breakdown

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Yukin, et al.

• Study design 2 week pre-post study
• 6 overweight adults
• Fixed carbohydrate composition (lt 50 g/d)
• Unlimited calories, protein, fat
• Results
• All subjects lost weight, between 2 9 pounds.
• All subjects decreased caloric intake by 13
  55.
• Conclusion
• Subjects self-select fewer calories when
  consuming a high fat diet.
• Weight loss is inversely proportional to caloric
  intake.

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Kekwick, et al.

• Study design I randomized cross-over
• 6 obese adult (gt35 MLS) inpatients
• Fixed diet composition (47 C, 33 F, 20 P)
• Variable caloric intake (2000, 1500, 1000, 500)
• Alternating every 7 9 days
• No wash-out period
• Urea-dilution method to determine fluid losses
• Moderate exercise permitted
• Results
• Decreasing caloric intake resulted in weight
  loss.
• 30 50 of weight loss was water as calculated
  by urea-dilution method.

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Kekwick, et al.
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Kekwick, et al.

• Study design II randomized cross-over
• 14 obese adult (gt35 MLS) inpatients
• Fixed caloric intake (1000 calories)
• Variable diet composition (90 C, 90F, 90P)
• Alternating every 5 9 days
• No wash-out period
• Moderate exercise permitted
• Results
• Weight loss was most rapid with 90 fat intake.
• No weight loss occurred with high carbohydrate
  diet. Some mild weight gain was
  observed.

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Kekwick, et al.
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Kekwick, et al.

• Study design III pre-post study
• 5 obese adult (gt35 MLS) inpatients
• Well-balanced 2000 calorie diet for 7 days
• Caloric intake increased to 2600 and
  carbohydrate intake decreased
  to minimal
  for variable durations (4-14 days)
• Moderate exercise permitted
• Results
• Weight loss occurred on high calorie,
  low- carbohydrate diet
  (1 2.6 kg).

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Kekwick, et al.

• Conclusions
• Weight loss is inversely proportional
  to caloric intake.
• Greater weight loss occurs with high fat diets.
• Fat digestion stimulates more caloric
  expenditure.
• Weaknesses
• Variable study durations
• Questionable subject compliance

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Yang, et al.

• Study design randomized cross-over
• 6 obese adult (gt92 desirable weight) inpatients
  
• Fasting 800 calorie/10 g CHO 800 calorie/90 g
  CHO formulas
• Alternating every 10 days
• 5 day wash-out on 1200-calorie balanced diet
• Energy-Nitrogen Balance
• Energy loss caloric intake energy expenditure
• Energy expenditure measures by indirect
  calorimetry
• resting, lying awake, sitting, standing, walking
  
  determined 3 x during every 5 day interval
• collectable excreta
• Protein loss nitrogen loss 6.25
• Fat loss (energy loss (nitrogen loss
  25.6))/9.3
• Water loss weight loss (protein loss fat
  loss)

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Yang, et al.

• Results
• Greatest weight, protein, fat, and water losses
  were associated with fasting.
• Rates of weight loss were greater with low CHO
  than high CHO diets (467 g/d v
  278 g/d)
• No significant differences observed in protein or
  fat loss between diets.
• Protein loss Low CHO 18 g/d High CHO
  10 g/d
• Fat loss Low CHO 164 g/d High CHO
  167 g/d
• During wash-out, a 52 g/d weight gain was
  observed following the low CHO diet
• Associated with water retention (181 g/d) but
  persistent fat and protein losses
• During wash-out, weight loss continued following
  the high CHO diet.
• Associated with 73 fat, 3.7 protein, and 23
  water losses
• Conclusions
• Low carbohydrate diets produce more rapid weight
  loss over the short-term.
• Discrepancies in weight loss can be explained
  solely by water losses.

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Lewis, et al.

• Study design randomized cross-over
• 10 obese adult male inpatients
• Fixed 10 kcal/kg/day intake and 20 protein
  intake
• Variable carbohydrate (70C/10F v. 10C/70F)
• Alternating every 14 days
• 7 day wash-out on 30 kcal/kg/day
  (40C/20P/40F)
• Daily 24-hour urine Na collections
• Results
• Low carbohydrate diet produced significantly more
  weight loss (0.8 kg)
• 44 meq/d urine Na with low carbohydrate diet
• 10 meq/d urine Na with high carbohydrate diet
• Increased albumin with low carbohydrate diet
• During wash-out, weight rebounded following low
  carbohydrate diet.

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Lewis, et al.

• Conclusions
• Weight loss is greater with low-carbohydrate
  diets over the short-term.
• Discrepancies can be attributed to water loss.

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Rabast, et al.

• Study design A comparison trial (15 - 78 days)
• 45 obese adult inpatients
• Fixed 1000 caloric formula
• Variable carbohydrate composition
• 25 g CHO n 25
• 170 g CHO n 20
• Study design B comparison trial (10 60 days)
• 29 obese adult inpatients
• Fixed 1900 caloric formula
• Variable carbohydrate composition
• 48 g CHO n 16
• 355 g CHO n 13
• Results 40 drop out rate
• Significant differences in weight loss observed
  at day 15
• No significant differences in weight loss
  observed at day 25
• Significant differences in weight loss observed
  at day 30
• Conclusion
• Rabast concludes that low carbohydrate diets
  produce superior weight loss over longer
  durations.
• No definitive conclusions can be made because you
  cant account for all subjects.

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Alford, et al.

• Study design 10 week comparison trial
• 35 obese adult (20 - 40 MLS) outpatients
• Fixed 1200 calorie diet
• Variable carbohydrate composition
• 25 (72 g) n 12
• 45 (135 g ) n 11
• 75 (225 g) n 12
• Weekly nutrition and behavior education
• No exercise
• Weight and hydrostatic fat determinations
• Results
• All subjects lost body weight and fat.
• No statistically significant differences in
  weight or fat loss.
• Conclusion
• Over 10 weeks, there is no difference in weight
  or fat loss between
  low or high carbohydrate diets.

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Alford, et al.
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Golay, et al.

• Study design 6 week comparison trial
• 43 obese adults (BMI gt30) inpatients
• Fixed 1000 calorie diet
• Variable carbohydrate composition
• 15C, 32P, 53F (38 g CHO) n 22
• 45C, 29P, 26F (113 g CHO) n 21
• Regular nutrition (2/wk) and behavior (1/wk)
  education
• Twice daily standardized exercise
• Weight, skin fold, bioelectrical impedance, hip
  and waist circumference
• Results
• All subjects lost body weight and fat.
• No statistical significant differences in weight,
  fat loss, or body measurements.
• Weight loss Low CHO 8 kg High CHO 7 kg
• Fat loss Low CHO 9 kg High CHO 7 kg
• Conclusion
• Over six weeks, there is no difference in weight
  or fat loss between
  low or high carbohydrate diets.

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Golay, et al.

• Study design 12 week comparison trial
• 68 overweight obese adult (BMI gt25) outpatients
• Fixed 1200 calorie diet
• Variable carbohydrate composition
• 25 (75 g CHO) n 31
• 45 (135 g CHO) n 37
• Nutrition lecture
• Light to moderate physical activity
• Weight, skin fold, bioelectric impedance, waist
  and hip measurements
• Results
• All subjects lost body weight and fat.
• No statistical significant differences in weight,
  fat loss, or body measurements.
• Weight loss Low CHO 10 kg High CHO 9 kg
• Fat loss Low CHO 8 kg High CHO 7 kg
• Conclusion
• Over twelve weeks, there is no difference in
  weight or fat loss between
  low or high carbohydrate diets.

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Lean, et al.

• Study design 6 month randomized control trial
• 110 overweight obese female (BMI gt25)
  outpatients
• Fixed 1200 calorie diet
• Variable carbohydrate composition
• 35 (105g CHO) n 53
• 58 (174 g CHO) n 57
• Weight, waist and hip measurements
• Results
• Approximately 75 of each group completed the
  study
• All subjects lost body weight and fat.
• No statistical significant differences in weight,
  fat loss, or body measurements.
• Weight loss Low CHO 7 kg High CHO 6 kg
• Fat loss Low CHO 2.5 High CHO 2.9
• A subgroup of 23 matched postmenopausal women
  lost significantly more weight on low
  carbohydrate diet (3 kg)
• Conclusion
• Over six months, there is no difference in weight
  or fat loss between low or high carbohydrate
  diets.
• Over six months, there is greater weight loss
  from low carbohydrate diets in postmenopausal
  women.

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Larosa, et al.

• Study design 8 week pre-post study
• 24 obese adult (gt10 MLS) outpatients
• Unlimited calories
• Limited carbohydrate composition
• lt 20 g carbohydrate for 4 weeks
• Increase daily carbohydrate by 5g/wk for 4 weeks
• Maintain current level of physical activity
• Weight measurements and laboratories every 2
  weeks
• Twice daily urine ketones
• 1 year telephone follow-up
• Results
• Participants lost an average of 8 kg over 8
  weeks.
• Half of weight loss occurred during first two
  weeks.
• Participants self-selected 500 fewer calories per
  day
• An average 6 kg weight loss was maintained at one
  year
• 9 subjects lost to follow-up
• Still following study diet?
• Conclusion
• Low carbohydrate diets are effective for weight
  reduction over an eight week period.

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Westman, et al.

• Study design 6 month pre-post study
• 41 overweight and obese adult (BMI 26-33)
  outpatients
• Unlimited calories
• Limited carbohydrate composition
• lt 25 g carbohydrate daily
• Increase daily carbohydrate to 50 grams when 40
  target weight loss achieved
• Aerobic exercise 3x week
• Measurements every other week for 12 weeks, then
  every other month
• Dietary records obtained randomly from days 8-14,
  28, 112
• Urinary ketones every other week for 12 weeks,
  then every other month
• Standardized body weight
• Skin fold thickness to estimate body fat
• Results
• Body weight decreased an average of 9 kg or 10
  over six months
• Body fat decreased and average of 3 over six
  months.
• Mean daily caloric intake was about 1500 calories
• Conclusion
• Low carbohydrate diets are effective for weight
  reduction over an six month period.

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Effectiveness of Weight Loss
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Effectiveness of Weight Loss
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Effectiveness of Weight Loss
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Effectiveness of Weight LossFuture Studies
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Effectiveness of Weight Loss

• Caloric restriction leads to weight loss.
• Low-carbohydrate diets produce more rapid weight
  loss over the short-term than high carbohydrate
  diets.
• Short-term differences are most likely the result
  of fluid losses.
• Over longer durations, there are no differences
  in weight or fat loss between isocaloric diets
  with low or high carbohydrate content.
• When calories are unlimited, low carbohydrate
  diets still produce weight loss.
• Self-selection of fewer calories

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Carbohydrate Metabolism
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Lipid Metabolism
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Sharman, et al.

• Study design 6 week controlled trial
• 20 normal-weight, normolipidemic male outpatients
  
• Calories to maintain body weight
• Limited carbohydrate composition
• 46g CHO (8C/61F/30P) n 12
• 306 g CHO (47C/32F/17P) n 8
• Weekly meetings
• Weekly measurements
• Daily dietary and urine ketone records
• Body weight at week 0, 3, 6
• Two consecutive 12-hour fasting blood samples at
  week 0, 3, 6
• Postprandial blood samples after fatty meal at
  week 0, 6

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Sharman, et al.

• Results
• No significant difference in calorie consumption
  (2400 cal) during the study
• Body weight decreased significantly by an average
  of 2.2 kg
• Ketones increased significantly by 250
• Fasting Insulin levels decreased significantly by
  33
• No significant changes in fasting glucose
• Total cholesterol responses were variable. CHOL
  increased 5
• TAG decreased significantly by 33
• Peak postprandial TAG decreased 24
• HDL responses were variable. HDL increased 12
• LDL responses were variable. LDL increased 4
• LDL diameter increased significantly
• No change in oxidized LDL
• VLDL cholesterol decreased significantly by 29
• No significant changes in control group

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Sharman, et al.

• Conclusions
• A six-week low carbohydrate diet can
  significantly decrease fasting insulin and
  triglycerides as well as postprandial lipemia.
• Effects on fasting total cholesterol, LDL, and
  HDL are equivocal.

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Other Metabolic Effects
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NutritionAnderson, et al.

• 7 daily 1600 calorie menu plans for each popular
  diet
• Atkins Diet, Protein Power, Sugar Busters, Zone
  Diet, ADA Diet, High Fiber, Pritikin, Ornish
• Diet Analysis
• Nutritionist IV
• Food guide pyramid score
• Results The Atkins diet
• Nutritionist IV
• Lowest carbohydrate and fiber
• Largest amount of fat, saturated fat, and
  cholesterol
• Food guide pyramid score
• Fewer servings of grains, vegetables, and fruits
  than the minimum
  recommendations

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NutritionAlford, et al.

• Study design 10 week randomized control trial
• 35 obese adult (20 - 40 MLS) outpatients
• Fixed 1200 calorie diet
• Variable carbohydrate composition
• 25 (72 g) n 12
• 45 (135 g ) n 11
• 75 (225 g) n 12
• Daily dietary records
• 3 records randomly selected each week
• Records analyzed by Ohio State Nutrient Data Base
• Nutrient intake compared to 1989 RDA
• Adequate diet 2/3 RDA requirements
• Results
• Low carbohydrate diets exceed RDA protein
  requirements.
• Vitamin A C are higher in high carbohydrate
  diets
• Low carbohydrates are deficient in thiamine and
  iron.
• Also deficient in sodium, magnesium, copper,
  chromium, molybderm, panthothenic acid
• Conclusion
• Nutritional supplementation is necessary.

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NutritionKennedy, et al.

• USDA sponsored research program
• Determine health nutritional effects of popular
  diets
• Objectives
• Critical analysis of data
• Comprehensive review of the literature
• Development of research protocols
• Continuing Survey of Food Intake (1994
  - 1996)
• 10,014 adults
• Telephone surveys
• food intake over the previous 24 hours
• two nonconsecutive days at least 3-10 days apart

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NutritionKennedy, et al.

• Diet analysis
• Nutrient quality
• UDSA Health Eating Index (0 100)
• 10 components (maximum 10 points each)
• grains, vegetables, fruits, meat, milk, total
  fat, saturated fat, cholesterol, sodium, variety
• Energy consumption
• Body mass index
• Results
• Significantly higher HEIs with high carbohydrate
  diet relative to low carbohydrate diets (71.2 v
  44.6)
• Lower caloric intake with high carbohydrate diets
  (1895 v 2026)
• Highest BMIs with low carbohydrate diet
• BMI data not available for 228 subjects

77
NutritionKennedy, et al.

• Conclusions
• On average, low carbohydrate diets have lower
  nutrient quality, high caloric intake, and higher
  associated BMIs.

78
Efficacy and Safety of Low-Carbohydrate DietsA
Systematic ReviewBravata, et al.

• Objective
• Evaluate the effects of low-carbohydrate diets on
  weight, lipids, fasting glucose and insulin, and
  blood pressure in outpatient setting.
• Study selection
• 2609 Medline articles (1/1/1966 2/15/2003)
• 107 articles describing 94 dietary interventions
• Adult outpatients (3268)
• low-carbohydrate (specified)
• gt 500 calories (specified)
• gt 4 days duration
• Evaluate at least one clinical outcome

79
Efficacy and Safety of Low-Carbohydrate DietsA
Systematic ReviewBravata, et al.

• Study variables
• Participants
• no significant differences in age, sex, weight,
  metabolic factors, or BP at baseline
• Sex
• Age (20 64)
• Baseline weight (57 217 kg)
• Fasting glucose, insulin, lipid profiles
• Diets
• Calories (525 - 4629 kcal/d)
• Carbohydrate content (0 901 g/d)
• lt 60 grams (n 663)
• gt 60 grams
• Duration (4 365 days)

80
Efficacy and Safety of Low-Carbohydrate DietsA
Systematic ReviewBravata, et al.

• Variable analysis
• Studies were heterogeneous
• Diets
• Ethnicity
• Energy expenditure
• Adherence
• No study evaluated low CHO diets in age gt 53.
• No studies evaluated participants with
  hyperlipidemia or DM.
• Low CHO diets had significantly fewer calories
  than high CHO diets
• 71 participants in low CHO diets lt 20 grams
• 5 studies evaluated low CHO diets for gt 90 days

81
Efficacy and Safety of Low-Carbohydrate DietsA
Systematic ReviewBravata, et al.

• Data Synthesis
• Weight loss
• Lower calories
• Diets with the greatest weight loss had variable
  CHO content but had consistently fewer calories.
  
• Lowest CHO diets did not result in greater weight
  loss.
• Longer duration
• Higher baseline weight
• Metabolic effects
• No significant changes of glycemic profiles
• No significant changes of lipid profiles
• Reductions in LDL were associated with higher
  baseline weight, weight loss, younger age,
  caloric intake, and longer duration.
• No significant changes of blood pressure

82
Efficacy and Safety of Low-Carbohydrate DietsA
Systematic ReviewBravata, et al.

• Conclusions
• Weight loss is associated with caloric
  restriction and diet duration.
• There is insufficient evidence to make
  recommendations for or against the use of
  low-carbohydrate diets. especially..
• Carbohydrate lt 20 g/d
• Individuals gt age 50
• Duration gt 90 days

83
Conclusions

• Effectiveness of Weight Loss
• Caloric restriction leads to weight loss.
• Low-carbohydrate diets produce more rapid weight
  loss over the short-term than high carbohydrate
  diets.
• Short-term differences are most likely the result
  of fluid losses.
• Over longer durations, there are no differences
  in weight or fat loss between isocaloric diets
  with low or high carbohydrate content.
• When calories are unlimited, low carbohydrate
  diets still produce weight loss.
• Self-selection of fewer calories

84
Conclusions

• Metabolic effects
• Carbohydrate metabolism
• Lower fasting insulin and glucose
• No studies with diabetics
• Lipid metabolism
• Lower triglycerides
• Variable effects on total cholesterol, HDL, LDL
• No published studies with hyperlipidemia
• Carbohydrate restriction or weight loss?
• Degree of carbohydrate restriction?
• Nutritionally Deficient

85
Conclusions

• Future studies
• Large randomized control trials
• Long durations
• Low-carbohydrate, unlimited calories
  v. Low-calorie, high-carbohydrate
  diets
• Diabetics
• Hyperlipidemia
• Age gt 53