Lecture 6: Food, exercise, and obesity Flashcards
What is type I diabetes?
Type I is where the pancreas fails to produce insulin so the muscles aren’t able to use glucose
What is type II diabetes?
Type II is where the body develops an insulin resistance so the muscle is not using glucose as effectively
What is insulin resistence? How does it occur?
Insulin resistance is when a person has a high card/sugar diet, resulting in constant high blood glucose levels, which require constant high insulin demands.
This causes the cells that have insulin receptors to become resistant to insulin (the body becomes used to it)
This means that these cells aren’t converting enough glucose and aren’t getting enough energy, so the body sends hunger signals to get more food (more hunger and craving). This maintains high glucose and insulin levels, which can cause other health problems
high carb diet -> constant high blood glucose -> constant high insulin demand -> insulin receptors become resistant -> starving cells, high blood glocuse and insulin levels -> hunger and craving -> other health problems + cycle repeats
What is Atherosclerosis?
Atherosclerosis is thickening or hardening of the arteries caused by a buildup of plaque in the inner lining of an artery
What are the three steps of Atherosclerosis?
Due to factors like a fatty diet or smoking, the irrant LDL builds up in our artery. LDL will cause endothelial dysfunction, where the permeability of the endothelial cells is damaged, allowing more cells to pass through the layer.
LDL will then go into the tunica intima, where it is not supposed to be. The macrophages that consume and destroy LDL will then follow them into the tunica intima.
Once the macrophages are filled and die off, they become foam cells and are stuck in the tunica intima. This build up causes a streak of fat to be built up. Narrowing arteries, causing lots of health problems such as increased blood pressure
What is Metabolically obese, normal weight (MONW)?
refers to people who appear to be thin/healthy but have large amounts of visceral fat in their bodies.
also called Skinny Fat”, “Fat inside thin outside” (FOTI)
What is the obesity paradox?
MONW are at higher risk for cardiovascular disease and type 2 diabetes than obese or overweight individuals
In populations with Cardiovascular disease undergoing coronary interventions/have coronary artery disease: Increasing BMI -> Decreased Morbidity and Mortality
Individuals with diabetes have a higher mortality risk if the are at “normal” weight than individuals who are overweight or obese
What is the Obesity-Depression-Inflammation Cycle?
Obesity causes greater amounts of inflammation
* Increased IL-6 and TNF-α
* Increased CRP, which also has a impact on mental health, increasing negative mood
Obesity and abdominal fat are related due to lack of control and increased stress in environment. Also increases depression
People with depression are more likely to engage in sickness behaviours, which can cause changes in eating habits, which may increase obesity
See diagram
How does stress influence the Obesity-Depression-Inflammation Cycle?
Stress increases IL-6 which increases inflammation, which increases pain, which increases sickness behaviours, causing diet changes that can contribute to obesity
Leptin reduces hunger, and obesity is associated with leptin receptor resistance
Increased stress -> increased leptin receptor resistance -> increased hunger -> increased weight gain
How much sugar does the WHO say we should have?
WHO guidelines state that we should have <6tsp (25g) of free sugar (glucose, fructose, sucrose) per day
Free sugar: all monosaccharides and disaccharides added to foods, plus sugars naturally present in honey, syrup, and fruit juices
Our food is very high in sugar, causing us to easily go over the recommend limit
What is the “just eat less” solution to obesity? What is the problem with this idea?
- Energy Surfeit Theory/“Calories in, Calories Out”
- But not all calories are equal
- Energy Balance Equation (thermodynamics): Energy intake = internal heat produced + external work + energy stored
- Calories burn off differently because of different metabolic processes (chewing, digestion, storage, etc.) for different types of nutrients
- e.g. 1 gram of fat/alcohol/card is 9/7/4 cal, but needs 2-3/20-35/5-15 % of energy to process
What is the “Just Exercise More” solution to obesity? What is the problem with this idea?
- The idea that we can simply work out more
- But exercise needed for long term weight loss maintenance far exceeds capacity for many people
- Mathematical model of weight loss (Hall et al., 2011)
- 1 calorie = 0.004 megajoules (MJ)
- Base energy burn-off for 220lb man ≈ 0.9MJ/day. Therefore burn >0.9MJ/day for weight loss
- Would need to run about 20km/week to burn off 1.2MJ/day (~71 additional calories/day)
- It would take about 5 years to lose ~30lbs
How much exercise is recommened due to the relation of moderate-to-vigiourous physical activity to mortiality?
150 - 300 minutes
How does Physical activity impacts the stress system?
- Physical stressor that activates the HPA axis
- Generalized adaptations to stressors of all kinds
- ^ causes a lower stress response -> reduced allostatic load -> reduced risk of chronic disease & stress-related illnesses
- E.g Cardiovascular disease (CVD), hypertension, depression
How does exercise reduce inflammation?
Higher levels of pro-inflammatory cytokines is a risk factor for several chronic diseases
* CRP -> CVD risk
* Interluekin-6 (IL-6) and tumor necrosis factor alpha (TNF-⍺) -> CVD, diabetes, cancer risk
* high in depression
Inverse relationship between pro- inflammatory markers and physical activity/aerobic fitness (Beavers, Brinkley,& Nicklas review, 2010) (intensity matters)
Therefore, exercise reduces pro-inflammatory cytokines, and thus reduces inflammation
