If these walls could talk, what would they say?? In the 8 years since the inception of the UW Nutrition and Exercise Lab, these walls have seen lots of data collection. That might sound boring to some, but contrary to popular belief, not all research is in the form of analyzing test tubes full of steaming chemical concoctions. Data collection can take on many different forms. Our current study, investigates the role of the appetite regulating hormones ghrelin, PYY, and GLP-1 in postpartum body weight regulation. That sounds like a lot of big words! How do researchers do that?! This is going to be a three part blog post that breaks down our research methods and concludes with an insight into understanding the phrase: “Researchers say…”
Research always begins with a question. The best part is; everyone is a researcher! Everyone comes up with a hypothesis, a way to test the hypothesis, and results to conclude the inquiry. For example, all students are researchers. They ask the question: how much do I need to study to get (desired grade)? They come up with a hypothesis: I will need to study X number of hours per week in order to get (desired grade). They will test this hypothesis with the first exam and their results show them whether X number of hours was sufficient or not.
Our research question began when Dr. Larson-Meyer questioned the nature of weight retention during the postpartum period. Why do some women tend to gain/retain weight after giving birth, while others lose weight? How does this affect the breastfed baby? Dr. Larson-Meyer’s knowledge of appetite regulating hormones directed her to propose that the appetite stimulating hormone ghrelin and the appetite suppressing hormones PYY and GLP-1, play a role in energy intake and body weight retention. We thought that these hormones were in breastmilk, but if so how would they effect the baby’s milk consumption and the baby’s growth?
We look at many different factors and because our study is longitudinal, we collect data at three time points; 1 month (baseline), 6 months, and 12 months after birth. We also have a group of control women who have never been pregnant to compare our results to. A grand total of 24 postpartum women, and 20 controls enrolled in this study.
After completing a screening visit, to ensure the safety and health of our participants, we bring them in to the lab fasting for a 5-hour test day. During this test day, we collect a urine sample and then have the participant lie in a bed and relax, while we place a plastic hood with hoses (see picture) over their head. This is called a resting metabolic rate (RMR) and it measures how much energy a person burns while at rest.
After 30 minutes of measurement, we draw baseline blood and then provide a breakfast smoothie. At 30 minute intervals, we draw blood for later analysis of the appetite regulating hormones, for a total of two and a half hours. Before each blood draw, the participant is asked to rate how hungry they feel. The participant is then taken in to the kitchen where a meal has been prepared. They can eat as much as they want in twenty minutes. We draw one more sample of blood one hour after meal initiation. After completing a few questionnaires about physical activity, eating behaviors and body image, the participant is released until we see them again 6 months later. Overall this test allows us to measure how the appetite hormones are altered by a standardized meal and whether this response predicts hunger, food intake and body weight change over 6 months and one year. Stay tuned for the description of the 6 and 12 month follow-up!!