Acute and Chronic Effects of Obesity on Cardiovascular Disease Risk Factors

(Présentement, le texte de cette page est disponible seulement en anglais)
 
Principal Investigator
Santosa, Sylvia (Department of Exercise Science, Concordia University)

Mentor
Simon Bacon & Jose Morais

Network Affiliation
Canadian Vascular Network

 

1. The Health Problem/Issue

Obesity is projected to surpass smoking as the #1 risk factor for cardiovascular disease. However, not all obese individuals are the same. Two people of the same sex, height and weight can have vast differences in CVD risk. For example, one might have high cholesterol or diabetes while the other does not. Even with the same amount of weight loss, some overweight people are able to lower their cholesterol more than others. We do not know why these differences exist. One reason may be the length of time someone has been overweight. We know that compared to people who only become overweight as adults, people who have been overweight from childhood to adulthood are at almost twice the risk of developing heart disease. Being overweight since childhood also puts people at a higher risk of having a stroke later in life. Of particular concern is the fact that right now in Canada, 1 in 4 children are overweight. It is very likely that these overweight children will become overweight adults. At present, we do not understand what the long-term effects are of childhood obesity on our bodies. If we can understand how early life obesity carried into adulthood puts us at greater risk of disease, we may be able to better target disease treatment and prevention in these individuals.
 

2. The Objectives 

Why is disease development and response to treatment different in some obese people than others? This is the main question that my research hopes to answer. Perhaps it is associated with when one develops obesity. Overweight people who have been so since childhood are at especially high risk of heart disease and stroke. I want to know why these people are at higher risk. Maybe it is because being overweight as a child affects the body differently than becoming overweight as an adult? Specific questions I would like to answer are: How does developing obesity as a child affect fat and muscle differently than if we gain weight as adults? Do obese adults who were overweight children respond differently to weight loss than those who became obese as adults?
 

3. The Approach

We will recruit people to volunteer in our research studies to help answer our questions. In these volunteers we will measure how much fat and muscle they have and how much energy they burn. We will also collect fluids (blood and urine), and tissue (fat from the stomach and legs, and muscle). Doing so will allow us to see what their disease risk is (e.g. how much cholesterol they have), if their cells are normal, and to measure proteins that might tell us the types of energy they use (e.g. fat, protein or sugar). To answer our first questions we will recruit two groups of people. One group will be made up of obese adults who developed obesity as teenagers. The other group will be made up of obese adults who only became overweight as adults. We will collect blood, fat and muscle tissue samples from people in each of these groups before and after a weight loss program. This will allow us to see whether our measurements were different before they lost weight. We will also be able to see if these two groups respond to weight loss differently.
 

4. The Unique Factors 

No one knows why some obese people develop diseases and others do not. We also do not know why obesity treatments work better in some people than in others. My program examines these differences from a unique angle, comparing long vs. short term effects of weight gain in the body. It would seem that being obese from childhood is different than if someone becomes obese as an adult. As well as having a greater disease risk, those people who carry excess weight from childhood into adulthood have more and smaller fat cells. People with more and smaller fat cells have a harder time losing weight compared to people with larger fat cells. My research will look at what it is about the tissue of people who developed obesity early in life that makes it difficult to treat and puts them at greater risk of disease.
 

5. How the project is relevant to the objectives of the initiative 

Those who have been overweight since childhood are at particularly high risk of heart disease and stroke. They are at seven times the risk of heart disease compared to people who were never obese. They are also at twice the risk of heart disease than people who developed obesity later in life. People who have been overweight since childhood are also at greater risk of having high blood pressure, the number one risk factor of stroke. Even if these individuals do not develop high blood pressure, they are more likely to have stroke than others who were lean as kids. My research program aims to understand the long-term effects of obesity. I will focus on people who have been obese from childhood to adulthood because they are at high risk of cardiovascular disease. In particular, I want to know whether there are better ways we can prevent disease and treat obesity in these individuals.
 

6. The Impact

Childhood obesity may have effects in our body that are long lasting, causing greater risk of heart disease and stroke. We do not truly know what these effects are and what causes them. Understanding what the long lasting effects are of childhood onset obesity provides us with targets that we can use to prevent heart disease and stroke in these individuals.
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