1. Scientific Inquiry Tied to Genetics, Evolution, and Obesity Module 4.1

2. Scientific Inquiry
The field of nutrition is based on scientific study that integrates biology, physiology, microbiology, botany, 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
Advances in nutrition are made using the scientific method.
The scientific method uses:
an unbiased approach to examine the interaction of food, nutrients and health.
is driven/guided by a hypothesis
Follows a basic format:
Ask a question (define the problem)
Form a hypothesis-statement
Design an experiment
Collect, analyze & interpret the data
Generalize & publish the findings
Ask another question (the findings generally leads to more questions)
The study of health and disease trends and patterns is called epidemiology.

4. The Scientific Method Design the study to test the hypothesis
A validated hypothesis may lead to a theory such as the theory of evolution or the thrifty gene theory

5. Experimental Design A well-conducted experiment requires
An Adequate sample size
number of subjects used in a study
Controls- assures subjects did as requested
control group and treatment group
comparison of treated and untreated individuals
prevention of experimenter bias
Psychosomatic Effects
effects of the subject’s state of mind on his or her physiology
use of placebo in control group
Statistical testing – supports measurable data
provides statements of probability
provides evidence of results

6. Examples of Theories in Science and Nutrition
Theory
Scientific Explanation
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.
Evolution
The change in heritable genetic composition of a population, such as by gene mutation and as a result of natural selection. There are several theories about how life forms began on earth; the well accepted theory of evolution is one of them.
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.
Thrifty gene
Humans who efficiently stored food energy as body fat survived tough times during the hunter-gatherer period of human existence. Natural selection of these thrifty genetic traits through evolution may lead to present day obesity when the person lives in a toxic food environment and leads a sedentary lifestyle.
There are many factors involved in survival; energy storage ability is one of them.
Glucostatic
Blood glucose levels affect overall bodyweight; mild hypoglycemia is associated with elevated levels of insulin which inhibits the satiety center and promotes positive energy balance. Normal glycemia results in satiety and better weight control. There are many factors involved in bodyweight control; glycemia is one of them.

7. Research Designs and Study Types
Case studies- Results from a single person protocol conducted by a medical doctor.
Clinical studies- Experimental design with a group of people.
Observational or Epidemiology- Population based, retrospective or prospective. Often retrospective (looking back) and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Intervention trials - Population based, retrospective or prospective. often prospective (looking forward) and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Laboratory experiments - Experimental design with any life form; microorganisms, virus, animals, plants, cell lines, bugs, etc.
Testimonials are NOT
based on research!!

8. Experimental Design things 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. Epidemiological study results reveal an obesity epidemic

12. Obesity: An Epidemic
Obesity is body fatness significantly in excess of the level that is consistent with optimal health.
There has been an uncontrolled rise in obesity in the United States over the last 20 years.
Obesity is defined by Body Mass Index (BMI).
American Heart Association as of 7/2016 indicated
almost 13 million (16.9%) of U.S. children ages 2 to 19 are obese.
Nearly one in three (31.8%) U.S. children (23.9 million) ages 2 to 19 are overweight or obese.
More than one-third (about 35%) of U.S. adults are obese (more than 78 million adults).

13. BMI BMI= wt(kg)÷[ht(m)]2 BMI RISK <18.5 18.5-24.9 25-29.9 30-34.9
≥40
Underweight
Normal
Overweight
Obesity (class I)
Obesity (class II)
Extreme Obesity
BMI
BMI= wt(kg)÷[ht(m)]2
BMI 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Ht
Wt (lbs) 60 97
102
107
112
118
123
128
133
138
143
148
153
158
163
168
174
179 61
100
106
111
116
122
127
132
137
164
169
180
185 62
104
109
115
120
126
131
136
142
147
175
186
191 63
113
124
130
135
141
146
152
197 64
110
134
140
145
151
157
192
204 65
114
144
150
156
162
198
210 66
155
161
167
173
216 67
121
159
166
172
178
211
217
223 68
125
171
177
184
190
203
230 69
149
176
182
189
196
209
236 70
139
160
181
188
195
202
222
229
243 71
165
193
200
208
215
250 72
154
199
206
213
221
228
235
242
258 73
212
219
227
257
265 74
194
218
225
233
241
249
256
264
272 75
224
232
240
248
279

14. Why is Obesity of Concern?
Epidemiological studies have conclusively verified the significant rise in obesity. Why the concern?
Raises blood cholesterol and triglyceride levels.
Heart disease
Lowers "good" HDL cholesterol. HDL cholesterol linked with lower heart disease and stroke risk
Hypertension - causes your blood to pumping through the heart and blood vessels with too much force.
Over time, consistently high blood pressure tires the heart muscle and can enlarge it.
Induces diabetes & cancer - Type 2 diabetes becoming more prevalent in obese adults & children. Obese children are more likely to become obese adults.
Type 2 diabetes affects the way your body metabolizes sugar by either resisting or not producing enough insulin
Liver/gallbladder disease (overworked due to high fat diets)
Arthritis / Hernia / Varicose veins
High-risk pregnancy
Accidents
Depression; low self esteem; decreased longevity, life quality

15. Obesity Trends* Among U.S. Adults BRFSS, 1991, 1999, 2008, and 2010
(*BMI 30, or about 30 lbs overweight for 5’4” person)
1991
1999
For updates go to
2008
2010
No Data <10% %–14% %–19% %–24% %–29% ≥30%

16. Behavorial Risk Factor Surveillance System, CDC. 2014