Exploring Scientific Inquiry in Nutrition and Obesity Studies

1. Module 4.1 Scientific InquiryTied to Genetics, Evolution, and Obesity

2. Scientific Inquiry • The field of nutrition is based on scientific study that integrates : • Biology • Physiology • Microbiology • Botany • Biochemistry • Chemistry • Genetics and • Molecular biology • In order to understand how evidence is produced, it is crucial to understand the basics of scientific inquiry.

3. The Scientific Method • Is hypothesis driven • Follows a basic format • Ask a question (define the problem) • Form a hypothesis • Design an experiment • Collect, analyze & interpret the data • Generalize & publish the findings • Ask another question (the findings generally leads to more questions)

4. The Scientific Method

5. Examples of Theories in Science and Nutrition • Cell • The cell is the most basic unit of life, organisms are made of one or more cells, and new cells arise from existing cells. Years ago it was hypothesized that humans are born with a certain number of fat cells. Now it is known that fat cells can divide when they have been filled to capacity. • Set Point • There seems to be a range of body weight that is relatively easy to maintain and is genetically and physiologically controlled. The lower body weight range is more tightly defended to prevent starvation and preserve life. • There are many feedback mechanisms that influence intake and satiety.

6. Research Designs • Case studies • Clinical studies • Intervention trials • Epidemiology • Laboratory experiments • Testimonials are NOT • based on research

7. Study Types • Case:Results from a single person protocol conducted by a medical doctor. • Clinical:Experimental design with a group of people. • Epidemiological & Intervention:Population based. • Laboratory: Experimental design with any life form; microorganisms, virus, animals, plants, cell lines, bugs, etc.

8. Experimental Designthings to consider • 1. Number of Subjects: is there enough for statistical significance. • 2. Duration of the Study: is it long enough for conclusions to be made. • 3. Matching Groups: Ethnicity, gender, age, lifestyle, disease. • 4. Control Groups: experimental vs placebo. • 5. Reproducible Results: can the experiment be repeated and yield the same results. • 6. The Treatment Protocol: blind, double blind, crossover.

9. Treatment Protocol • Blind: the subject does not know if they are in the experimental or control group. • Double Blind: the subject and the primary investigator do not know who is in the experimental or control group. • Cross over: each group experiences a period of being on the placebo and experimental drug. • A highly reputable study design is called the double-blind cross over experiment.

10. Public Recommendations • Consistent results from multiple credible studies published over many years are used to make dietary recommendations. • A whole body of evidence, collected over many years of experimentation is interpreted by the scientific community to create public recommendations regarding diet and health (disease prevention).

11. OBESITY

12. OBESITY • Obesity is body fatness significantly in excess of the level that is consistent with optimal health. • Excess body fat is stored inside fat cells (adipose tissues) • That causes the mass or size of the cells increases. It known as Hypertrophy. • Once fat cells are filled up, then the fat cells can be divided or increase in cell number. This is referred to as Hyperplasia. • There has been an uncontrolled rise in obesity in the United States over the last 20 years.

13. OBESITY AS A CHRONIC DISEASE • Too much body fat increases a person's risk of developing a host of chronic health problems, those include: • High Blood pressure • Heart Disease • Diabetes • Gallbladder Disease • Arthritis • Sleep Disorder (sleep apnea) • Respiratory Problems • Cancers of Breast, Uterus, Prostate, and Colon

14. 1991 Obesity Trends* Among U.S. AdultsBRFSS,1991, 1999, 2008, and 2010 1999 2008 2010

15. Obesity • Obesity was 12% in 1991 and 33.8% in 2010 • More than 17% of children and adolescents age 2 to 19 years of age are obese. • The obesity during the last 20 years has doubled in adults and tripled in children. • Obesity is defined by Body Mass Index (BMI).

16. WHAT IS HEALTHY WEIGHT

17. HEALTHY WEIGHT • How much body fat is too much depends on: • Age • Life style and • Where fat is located • “Apple” profile •             “Pear” profile • Central Obesity • Fat that collects deep within the central abdominal area of the body (visceral fat)

18. BODY COMPOSITION • Healthy level of body fat: • For young adult female is between 21% to 32% • For young adult male is between 8% to 19% • With aging, lean body mass decreases and body fat increases. • Some of these changes may be prevented through exercise

19. BMI • Body Mass Index

20. BMI • It is current standard for assessing healthfulness of body weight. • Which determined by dividing weight (in kg) by height (in meters) square:

21. Body Weight versus Body Fatness • Body Mass Index (BMI) • BMI=wt. (Kg)/height (m) or • BMI=wt. (lbs.)/height (In)2x705 • BMI=140 lbs/(66)2in.=140/4356=0.0321x705  • BMI=22.65 or 23

22. BMI • The Healthy BMI for adults is between: • 18.5 to 24.9 • People with in this range have lowest health risks. • BMI is not actually a measure of body fat • It is recommended as a way to assess body fatness

23. BMI • 18.5 or less underweight • 18.5 – 24.9 normal • 25.0 29.9 over weight • 30.0 34.9 obese type I • 35.0 39.9 obese type II • 40.0 or higher extremely obese

24. Energy Balance Module 4.2

25. Principles of Energy Balance • 1 pound fat = 3500 Calories stored. • To lose body fat, a Calorie deficit needs to be created. • To gain body weight, a Calorie excess needs to be created. • Body weight changes are based on the relationship of Caloric (Energy) intake & Energy Expenditure.

26. Energy Balance Equations • Body Fat Mass change can be calculated with these formulas: • If Calories Consumed = Calories Expended (Isocaloric) • Body weight is typically maintained. Energy balance occurs. • If Calories Consumed > Calories Expended (positive energy balance) • Weight is typically gained . Positive energy balance occurs. • If Calories Consumed < Calories Expended (negative energy balance) • Weight is typically lost. Negative energy balance occurs.

27. Energy Expenditure • Basal Metabolic Rate (BMR: 60%– 65%) • An amount of energy needed to sustain life • Voluntary muscle movement-(Physical Activity: 25%-35%) • Calories burned in physical activity (PA) • The specific dynamic action (SDA) of food (also called the thermic effect of food: 5%-10%) • Energy required for food digestion & processing

28. Energy Expenditure

29. Basal Metabolic Rate (BMR): • The energy required by the body to minimally function (heart to beat, lungs to breathe, …). • It is determined in a fasting state (12 hours) and when the body is at complete rest. • Majority of expenditure in a sedentary person

30. Basal Metabolic Rate (BMR): • BMR is also called Resting Energy Expenditure (REE) • It considers the amount of energy burned by a person at rest. • REE can be measured in the lab or estimated using the Mifflin Equations.

31. The Mifflin EquationsAre based on gender, height, weight, and age REE Formula For WOMEN: • REE (Calories/day) = (10 x W) + (6.25 x H) – (5 x A) – 161 REE Formula For MEN: • REE (Calories/day) = (10 x W) + (6.25 x H) – (5 x A) + 5 • W= Weight in Kg (pounds divided by 2.2) • H = Height in centimeters (inches x 2.54) • A= Age in years

32. Factors That Affect The BMR • -       Age • -       Gender • -       Growth • -       Body Composition • -       Fever • -       Stress • -       Environmental Temperature • -       Fasting/ Starvation • -       Malnutrition • -       Thyroxin

33. Specific Dynamic Action (SDA): Specific Dynamic Action (SDA): • The food processing charge. • Also called the thermic effect of food. • ~10% of the total number of Calories consumed is required for the digestion, absorption & assimilation of nutrients into the body. • Metabolism is increased when fed

34. Body Composition & Weight Control Module 4.3

35. NEW YEAR RESULATION

36. HEALTHY BODY WEIGHT • “This year I am going to loose my weight once and for all” • Three (3) misconceptions •       Focus on weight •       The focus on controlling wt. •        Focus on a short term plan

37. HEALTHY BODY WEIGHT • It is not your weight you need to control • It is fat in proportion to lean(The Body Composition) • Controlling body composition is not possible- without controlling your behavior. • Sporadic bursts of activity (dietary) are not effective •  It is a life time commitment

38. Body Composition • Determination of body weight should be based upon body composition. • It is important to know the % of total body weight that is fat. • Values should be considered for maintaining good health, personal appearance, & performance reasons

39. Essential Fat Mass • Two classifications of body fat • – Essential – necessary for optimal health • • Fat in bone marrow • • Cell membranes • – Nonessential or storage • • Subcutaneous adipose tissue • . Visceral Fat

40. Essential Fat • In female, essential fat mass contributes about 12% of total body fat. • The higher body fat in women is required for normally functioning reproductive cycle. • Lower Essential Fat mass in women can cause disruption in the menstrual cycle, the condition is known as amenorrhea.

41. Determining Body Fat • Underwater weighing (very accurate) • Skin fold calipers (the more sights, the better) • Bioelectrical impedance (the persons hydration level affects the reading accuracy) • Futrex 5000 (more accurate when average body fat)-Light absorption, reflectance,& near-infrared spectroscopy.

43. Location of Body Fat

44. Location of Body Fat • Location of fat in body affects the risks associated with having too much fat. • Excess Subcutaneous Fat increase health risks relatively less than the excess Visceral Fat. • Visceral fat is more metabolically active than subcutaneous fat.

45. Location of Body Fat • Based on the fat deposit in the body people are divided into two groups: • “Apple” profile •             “Pear” profile • Central Obesity • Fat that collects deep within the central abdominal area of the body (visceral fat)

48. RICKS FROM CENTRAL OBESITY • Visceral Fat. Especially dangerous with regard to risks of: •       Diabetes •       Stroke •       Hypertension • Dyslipidemia • High Blood Cholesterol •       Coronary artery disease

49. Factors affecting fat distribution •       Smoking •       Moderate-to-high intake of alcohol •       Physical activity •       Menopause in women

50. Waist Measurement • Reflects the degree of visceral fatness in proportion to body fatness. • Men 40 inches (102 cm) • Women 35 inches (88 cm) • Anyone with the waist measurement larger than these standards may carry an increased risk of disease.