Weight Loss Diets
November 12, 2010
Michael Sharifi
Fitness and health are basically numbers. While exercising you count reps, sets, and
weight in addition to speed, power, and rest periods. In health you start by
calculating you’re BMI, resting heart rate, and calorie intake. As in math you have
formulas that you input data to find answers. Considering an industry of numbers
and mathematical equations there is little supporting research to countless factors
in health and fitness. Diet being one of the major industrial misconceived practices
surrounded by fad diets and unproven theories; even so Americans spend $40
billion a year on weight-loss programs and products.1
According to a 2006 study reported in The New England Journal of Medicine, most
people who participate in weight-loss programs “regain about one-third of the
weight lost during the next year and are typically back to baseline in three to five
years.”
This essay is on the effectiveness of various diets and the prolonged health issues
associated with fad diets. Throughout this essay explanations and formulas will be
introduced showing a correlation between the research and mathematical equations
learned in quantitative reasoning 1030. As there will be periodical definitions to
help bridge industrial terminology. Majority of the statistics come from a two-year
experimental trial study conducted October 2004 through December 2007 at two
sites; Harvard School of Public Health and Brigham and Women's Hospital, Boston;
and the Pennington Biomedical Research Center of the Louisiana State University
System, Baton Rouge.
1
http://www.businessweek.com/debateroom/archives/2008/01/the_diet_indust.html
A randomized clinical trial was designed to compare the effects on body weight of
energy-reduced diets that differed in their targets for intake of macronutrients —
low or high in fat, average or high in protein, or low or high in carbohydrates. A
ninety minute a week recommendations for cardiovascular health paralleled the
diet. The project staff of the National Heart, Lung, and Blood Institute also
participated in the development of the protocol, monitoring of progress,
interpretation of results, and critical review of the manuscript.
MACRONUTRIENTS
A substance required in relatively large amounts by living organisms, in particular
-a type of food (e.g., fat, protein, carbohydrate) required in large amounts in the human diet.
PRO•TEIN
Long chains of amino acids that are essential to the building blocks for DNA, concentrated on
structural components of the body tissues; muscle, hair, collagen, etc.
CAR•BO•HY•DRATES
Organic compounds occurring in foods, living tissues, including sugars, starch, and cellulose.
They contain hydrogen and oxygen in the same ratio as water (2:1) and typically can be broken
down to release energy in the human body.
LI•PIDS (FAT)
A group of compounds that includes triglycerides (fats and oils), phospholipids, and sterols.
Fatty acids may be saturated or unsaturated.
Saturated fatty acids are implicated as a risk factor for heart disease because they raise bad
cholesterol levels low-density lipoprotein (LDL). Measurement of 70 to 100 mg/dL is a fairly
healthy level.
Unsaturated fatty acids can be broken down into two categories and are associated with
increase of good cholesterol high-density lipoprotein (HDL)
Monounsaturated fatty acids one double bond in its carbon chain.
(Olive and canola oils)
Polyunsaturated fatty acid has two or more double bonds.
(Omega-3 fatty acids found in cold-water fish)
Population
There were a total of 800 participants to start the study of which 40% of them
where men. 800(0.40) = 320 men; 680 women between the ages of 30 to 70 years
old. Exclusion for the experiment was the presence of diabetes or unstable
cardiovascular disease, the use of medications that affect body weight, and
insufficient motivation as assessed by interview and questionnaire. Each individual
body-mass index (BMI) was between 25 to 40. (See BMI Chart)
Under Weight = <18.5
Normal Weight = 18.5-24.9
Over Weight = 25 – 29.9
Obesity = 30>
Sample Selection
Mass mailings were the primary means of recruitment; names were identified with
the use of lists of registered voters or drivers. All participants gave written informed
consent. They were informed that the study would be comparing diets with different
fat, protein, and carbohydrate contents and that they would be assigned a diet at
random.
Random assignments to one of four diet groups were generated by the data
manager at the coordinating center on request of a study dietitian, after eligibility of
a participant was confirmed. Two diets were low-fat and two were high-fat, and two
were average-protein and two were high-protein, constituting a two-by-two
factorial design.
The nutrient goals for the four diet groups were:
 20% fat, 15% protein, and 65% carbohydrates (low-fat, average-protein)
 20% fat, 25% protein, and 55% carbohydrates (low-fat, high-protein)
 40% fat, 15% protein, and 45% carbohydrates (high-fat, average-protein)
 40% fat, 25% protein, and 35% carbohydrates (high-fat, high-protein)
The four diets also allowed for a thermic effect through carbohydrate intake that
ranged from 35 to 65% of energy. Other goals for all groups were that the diets
should include 8% or less of saturated fat, at least 20 g of dietary fiber per day, and
150 mg or less of cholesterol per 1000 kcal. Carbohydrate-rich foods with a low
glycemic index were recommended in each diet. Each participant's caloric
prescription represented a deficit of 750 kcal per day from baseline, as calculated
from the person's resting energy expenditure and activity level. (The average
women caloric intake is 1800, average caloric intake for men 2200).
BMR -Basal Metabolic Rate
Men
[13.7516(kg) + 5.0033(cm) – 6.775(age) + 66.4730] = Kcal
1(kg)
1(cm)
1yr
Day
Women
[9.5634(kg) + 1.846(cm) – 4.6756(age) + 655.0955] =Kcal
1(kg)
1(cm)
1yr
Day





Sedentary = BMR X 1.2 (little or no exercise, desk job)
Lightly active = BMR X 1.375 (light exercise/sports 1-3 days/wk)
Mod. Active = BMR X 1.55 (moderate exercise/sports 3-5 days/wk)
Very Active = BMR X 1.725 (hard exercise/sports 6-7 days/wk)
Extra Active = BMR X 1.9 (hard daily exercise/sports & physical job or 2X day
training, i.e marathon, contest etc.)
Blinding was maintained by the use of similar foods for each diet. Staff and
participants were taught that each diet adhered to principles of a healthful diet 2 and
that each had been recommended for long-term weight loss, thereby establishing a
balanced state. Investigators and staff who measured outcomes were unaware of
the diet assignment of the participants.
Measurements
Body weight and waist circumference were measured in the morning before
breakfast on 2 days at baseline, 6 months, and 2 years, and on a single day at 12 and
18 months.
Diet
Dietary intake was assessed in a random sample of 50% of the participants, by a
review of the 5-day diet record at baseline and by 24-hour recall during a telephone
interview on 3 nonconsecutive days at 6 months and at 2 years. Daily meal plans
were provided for in 2-week blocks. Participants were instructed to record their
food and beverage intake in a daily food diary and in a web-based self-monitoring
tool.
Lichtenstein AH, Appel LJ, Brands M, et al. Diet and lifestyle recommendations revision 2006: a scientific statement from the
American Heart Association Nutrition Committee. Circulation 2006;114:82-96[Erratum, Circulation 2006;114(1):e27,
114(23):e629.]
2
Questionnaire
31 Questionnaires that asked for information on satiety, food craving, eating
behavior, and satisfaction with the diet (1) (2) were administered at baseline and at
6 months and 2 years.
Samples
Fasting blood samples, 24-hour urine samples, and measurement of resting
metabolic rate were obtained on 1 day, and blood-pressure measurement on 2 days,
at baseline, 6 months, and 2 years.
Levels
Serum lipids, glucose, insulin, and glycated hemoglobin levels were measured at the
clinical laboratory at the Pennington Biomedical Research Center. Blood pressure
was measured with the use of an automated device (HEM-907XL, Omron).
The information obtained from the participants was used to evaluate for the
presence of the metabolic syndrome.
METABOLIC SYNDROME
Metabolic syndrome is a combination of medical disorders that increase the risk of developing
cardiovascular disease and diabetes. It affects one in five people, and prevalence increases with age.
Some studies estimate the prevalence in the USA to be up to 25% of the population.
Defined by the presence of at least three of the following five criteria:
1. Waist circumference of more than 102 cm in men or more than 88 cm in
women
2. Triglyceride level of 150 mg per deciliter (1.69 mmol per liter) or more
3. High-density lipoprotein (HDL) cholesterol level of less than 40 mg per
deciliter (1.03 mmol per liter) in men or less than 50 mg per deciliter (1.29
mmol per liter) in women,
4. Blood pressure of 130/85 mm Hg or more, and a fasting glucose level of 110
mg per deciliter (6.1 mmol per liter) or more.
MMOL
mmol/l is millimoles/liter, and is the world standard unit for measuring glucose in blood.
Specifically, it is the designated SI (System International) unit.
Statistical Analysis
The primary outcome of the study was the change in body weight over a period of 2
years, and the secondary outcome was the change in waist circumference. Data were
pooled from the diets for the two factorial comparisons: low fat versus high fat and
average protein versus high protein.
RESULTS
Participants
Of 1638 participants who were screened, 811 (50%) were randomly assigned to a
diet, and 645 (80% of those assigned) completed the study (i.e., provided a bodyweight measurement at 2 years) (Chart. 1 in the Supplementary Appendix). Baseline
characteristics were similar among participants assigned to the four diets and
between those who were assigned to a diet and those who completed the study.
Weight Loss
The amount of weight loss after 2 years was similar in participants assigned to a diet
with 25% protein and those assigned to a diet with 15% protein (3.6 and 3.0 kg,
respectively; P=0.22) and among those who completed each of those diets (4.5 and
3.6 kg, respectively; P=0.11) Weight loss was the same in those assigned to a diet
with 40% fat and those assigned to a diet with 20% fat (3.3 kg, P=0.94) and was
similar among those who completed each of those diets (3.9 and 4.1 kg, respectively;
P=0.76). There was no effect on weight loss of carbohydrate level through the target
range of 35 to 65%The change in waist circumference did not differ significantly
among the diet groups.
As expected, most of the weight loss occurred in the first 6 months. There was less
than 0.5kg of body weight and 0.5 cm of waist circumference change among the four
diets. After 12 months, all groups, on average, slowly regained body weight.
According to the study “A total of 185 of the participants (23%) continued to lose
weight from 6 months to 2 years; the mean (±SD) additional weight loss was 3.6±3.5
kg, for a mean total loss from baseline of 9.3±8.2 kg, with no significant differences
among the diet groups. At 2 years, 31 to 37% of the participants had lost at least 5%
of their initial body weight, 14 to 15% of the participants in each diet group had lost
at least 10% of their initial weight, and 2 to 4% had lost 20 kg or more.”
Fad Diets
For every gram of glucose taken out of glycogen, it brings with it 2.7 g of water3
Atkins Diet
The Atkins diet is a high-protein, high-fat, and very low-carbohydrate regimen. It
emphasizes meat, cheese, and eggs, while discouraging foods such as bread, pasta,
fruit, and sugar. It is a form of ketogenic diet.
KETOGENIC DIET
Is a high-fat, adequate-protein, low-carbohydrate diet the diet mimics aspects of starvation by forcing
the body to burn fats rather than carbohydrates. Normally, the carbohydrates contained in food are
converted into glucose, which is then transported around the body and is particularly important in
fuelling brain function. However, if there is very little carbohydrate in the diet, the liver converts fat
into fatty acids and ketone bodies. The ketone bodies pass into the brain and replace glucose as an
energy source. An elevated level of ketone bodies in the blood, a state known as ketosis.
The regimen is a low-carbohydrate, or ketogenic diet, characterized by initial rapid
weight loss, usually due to water loss. Drastically reducing the amount of
carbohydrate intake causes liver and muscle glycogen loss, which has a strong but
temporary diuretic effect.
There have been no significant long-term scientific studies on the diet. A number of
leading medical and health organizations, including the American Medical
Association, American Dietetic Association (ADA), and the American Heart
Association oppose it. It is drastically different than the dietary intakes
recommended by the U.S. Department of Agriculture and the National Institutes of
Health. Much of the opposition is because the diet is lacking in some vitamins and
Karlsson J, Saltin B. lactate, ATP, and CP in working muscles during exhaustive exercise in man. JAppl Physiol 170;29(5):596602
3
nutrients, and because it is high in fat. In a hearing before the U.S. Congress on
February 24, 2000, an ADA representative called the Atkins diet "hazardous" and
said it lacked scientific credibility.
HGC
HUMAN CHORIONIC GONADOTROPIN (HYOO muhn kor ee ON ik goe NAD oh troe
pin) is a hormone. HCG is used for different reasons in men and women. HCG is used
in combination with other fertility drugs to increase a woman's chance of
pregnancy. In men or adolescent boys, HCG helps the production of testosterone and
sperm. HCG is also used in male children with cryptorchidism, a specific birth
problem of the testes.
A glycoprotein hormone produced in pregnancy that is made by the developing
embryo after conception and later by the syncytiotrophoblast (part of the
placenta).[3] Its role is to prevent the disintegration of the corpus luteum of the
ovary and thereby maintain progesterone production that is critical for a pregnancy
in humans. hCG may have additional functions; for instance, it is thought that hCG
affects the immune tolerance of the pregnancy. Early pregnancy testing, in general,
is based on the detection or measurement of hCG. Because hCG is produced also by
some kinds of tumor, hCG is an important tumor marker especially (with clinical
significance) in Gestational trophoblastic disease,[4] but it is not known whether
this production is a contributing cause or an effect of tumorigenesis.
Conclusion
Diets seem to follow a declining exponential model. In the first 6 months there is a
drop in weight and circumference. After the first 6 months the weight loss is
extended for longer periods before seeing similar results. Utilizing the tools such as
body-mass index (BMI) or the Basal Metabolic Rate (BMR) equation the individual
can approximate the proper amount of macronutrients (Protein, Carbohydrates, and
Fat) into their diet. Inputting a deficit of 500 – 750 kcal from the total kcal baseline.
The body should follow the fundamental theory of energy used or calories burned to
calorie intake; fat stores subsidize the energy needed.
Through mathematical data we can see statistical trends, as found in the research
done by various groups on diet are all subjective to the study, and not adhering to
the variables found in the real world. Each person is unique in genetic composition
where cause and affect becomes individualized. Focusing on the subject of topic,
healthy diets, one cannot assume through generic test, that what is good for the
group is good for the individual. This can be seen within the study utilizing
macronutrients; 20% fat, 15% protein, and 65% carbohydrates (low-fat, averageprotein), 20% fat, 25% protein, and 55% carbohydrates (low-fat, high-protein),
40% fat, 15% protein, and 45% carbohydrates (high-fat, average-protein), 40% fat,
25% protein, and 35% carbohydrates (high-fat, high-protein). After an 800 person,
2-year study no major changes or results came from the weight loss diet. This is due
to adaptation by individuals either by conserving energy (stored fat) or by muscle
adaptation, according to National Academy of Sports Medicine (NASM).
In the information obtained by Harvard School of Public Health and Brigham and
Women's Hospital, Boston; and the Pennington Biomedical Research Center of the
Louisiana State University System, Baton Rouge, the choice of intake of
macronutrients — low or high in fat, average or high in protein, or low or high in
carbohydrates evaluates to the individual eating habits. This is obtained by choosing
healthy foods enjoyed by an individual, within the parameters listed above. They are
more likely to stay on their diet as to eating healthy foods undesirable to the dieter.
This approach would appeal to the positive psychological process compared to the
negative association to dieting.
The dangers in obesity or in fad diets are the internal and prolonged effects that
they have on the body. There is a limited initial period where Fad Diets such as; the
Actins Diet can be beneficial for individual to assist in the jumpstart of the ketosis
process (body uses fat stores for energy). As in Actins Diet, high percentages of
protein can cause liver and kidney damage if subjected to extended periods, this is
due to the processing protein into energy. All Fad Diets are limited in nutrient and
therefore they need supplementation.
Fundamentally defining a healthy diet is eating a variety of natural foods (without
the use of pesticides or foods altered to withstand pesticides), clean food (not
processed or genetically enhanced) with high nutrient content. If we emulated our
ancestors we would find a healthy diet to be locally grown and fruits and vegetables
that are in season. Something to lookout for is processed food. According to Marion
Nestle a contributing writer of Food Inc., scientists have disguised corn within the
labels of 75% in food found at your local grocery store. Corn syrup and processed
foods contribute to America’s epidemic of diabetes. The UnitedHealth says Diabetes
will cost $3.4 Trillion over the next decade. That is equal to one fourth of the
National Debt today. Though self-educating individuals can help prevent the
numerous health problems that contribute to the financial expense.
The process of loosing weight or the goal of obtaining optimum health one should
include an exercise program that gradually increases in development, intensity, or
movement. Following a balanced program the individual would include cardio,
strength training, and flexibility (prescribed by your physician). This will increase
more success in any diet, especially in the following years.
September 10, 2007
PCRM Physicians Committee for Responsible Medicine
http://www.pcrm.org/news/release070910.html
The Secret to Long-Term Weight Loss Might Be a Vegan Diet, Research Finds
New Study in Obesity Shows a Vegan Diet with Social Support Helps People Lose
More Weight Over Two-Year Period than Conventional Low-Fat Diet
WASHINGTON—A new study in September’s Obesity shows that a vegan diet helps
people lose more weight and keep it off more effectively than a more conventional
low-fat diet that includes meat and dairy products. Social support in the form of
group meetings was also associated with greater sustained weight loss, according to
the study’s authors, who include health experts with the Physicians Committee for
Responsible Medicine (PCRM).
The study included 64 overweight, postmenopausal women randomly assigned to
either a low-fat vegan diet or a more conventional low-fat diet following the
National Cholesterol Education Program (NCEP) guidelines. Participants in each
group received either no follow-up support after the initial 14 weeks or continued
group support meetings for two years. The vegan group lost a median of 11 pounds
at one year, compared with four pounds for the control group. By the two-year
point, the vegan group had lost approximately seven pounds from baseline,
compared with approximately two pounds for the control group. Participants in
both groups who attended support meetings lost more weight at one and two years.
“People on the vegan diet shed more unwanted pounds, and avoiding meat and
dairy products also helped study participants achieve the Holy Grail of dieting—
significant weight loss sustained over several years,” said lead author Gabrielle M.
Turner-McGrievy, M.S., R.D., a PCRM nutrition scientist and doctoral candidate in
nutrition at the University of North Carolina at Chapel Hill. “This study offers more
evidence that vegan diets could help combat our country’s surging obesity rates.”
In the study—which Turner-McGrievy co-authored with Neal D. Barnard, M.D., and
Anthony R. Scialli, M.D.—vegan participants consumed plenty of fruits, vegetables,
whole grains, and other plant-based foods, but did not eat meat, eggs, or dairy
products.
Journalists who would like a copy of the paper in Obesity or an interview with one of
the authors can contact Tara Failey at 202-686-2210, ext. 319, or tfailey@pcrm.org.
Founded in 1985, the Physicians Committee for Responsible Medicine is a nonprofit
health organization that promotes preventive medicine, especially good nutrition.
Appendix
1- Flint A, Raben A, Blundell JE, Astrup A. Reproducibility, power and validity of visual analogue scales in assessment of
appetite sensations in single test meal studies. Int J Obes Relat Metab Disord 2000;24:38-48
2 - Urban N, White E, Anderson GL, Curry S, Kristal AR. Correlates of maintenance of a low-fat diet among women in the
Women's Health Trial. Prev Med 1992;21:279-291
3-Cole LA (2009). "New discoveries on the biology and detection of human chorionic gonadotropin". Reprod. Biol. Endocrinol.
7: 8. doi:10.1186/1477-7827-7-8. PMID 19171054
4-Gregory JJ, Finlay JL (April 1999). "Alpha-fetoprotein and beta-human chorionic gonadotropin: their clinical significance as
tumour markers". Drugs 57 (4): 463–7. PMID 10235686
The New England Journal of Medicine; Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and
Carbohydrates http://www.nejm.org/doi/full/10.1056/NEJMoa0804748#t=articleResults
Foster GD, Wyatt HR, Hill JO, et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med 2003;348:20822090
Yancy WS, Olsen MK, Guyton JR, Bakst RP, Westman EC. A low-carbohydrate ketogenic diet versus a low-fat diet to treat
obesity and hyperlipidemia: a randomized, controlled trial. Ann Intern Med 2004;140:769-777
Shai I, Schwarzfuchs D, Henkin Y, et al. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med
2008;359:229-241
NASM Essentials of Personal Fitness Training: course manual. -3rd ed. p. cm. ISBN 978-0-7817-8291-3
"Atkins Diet." Gale Encyclopedia of Medicine. 2008. The Gale Group, Inc. 21 Nov. 2010 http://medicaldictionary.thefreedictionary.com/Atkins+Diet