17b. Food Intake & Weight Loss Flashcards
1
Q
What are energy intake and body weight thought to be regulated by?
A
Homeostatic mechanisms
2
Q
What has challenged the theory that homeostatic mechanisms regulate energy intake and body weight?
A
Obesity epidemic
3
Q
How do we get a feeling of satiety when food and drink are in the stomach?
A
Causes stomach to distend
Activates mechanoreceptors in the stomach
4
Q
How do we get a feeling of satiety when food and drink are in the duodenum?
A
CCK is released
5
Q
How do we get a feeling of satiety when food and drink are digested?
A
Carbs turn to glucose
Fats turn to fatty acids
Proteins turn to amino acids
The presence of these nutrients makes the liver send signals to the brain via the Vagus nerve
6
Q
Which elements in the nervous system and digestion control appetite?
A
Hypothalamus/arcuate nucleus
Gut hormones
Neurotransmitters
7
Q
How does the arcuate nucleus control appetite?
A
Neurons stimulate or inhibit food intake
Neurons influence energy homeostasis
8
Q
How do gut hormones regulate appetite?
A
Act peripherally to modulate digestion and absorption of nutrients
Reach the hypothalamus from the circulation or via vagus nerve
9
Q
Examples of neurotransmitters that control appetite
A
Neuropeptide Y Cholecystokinin (CCK) Insulin Glucagon Glucagon-like peptide 1 Bombesin Ghrelin Leptin
10
Q
Which neurotransmitters increase appetite?
A
Neuropeptide Y
Ghrelin
11
Q
What does neuropeptide Y do to appetite?
A
Increases it
12
Q
What does cholecystokinin do to appetite?
A
Promotes satiety
reduces appetite
13
Q
What does insulin do to appetite?
A
Increases satiating effect of CCK
14
Q
What does glucagon do to appetite?
A
Glucose metabolism
Reduces appetite
15
Q
What does glucagon-like peptide 1 do to appetite?
A
Promotes satiety
16
Q
What does bombesin do to appetite?
A
Acts in similar way to CCK
peptide found in the brain
17
Q
What does ghrelin do to appetite?
A
Increases with food deprivation
May trigger hunger
18
Q
What does leptin do to appetite?
A
Promotes satiety
Stops feeding behaviour
19
Q
When is CCK released?
A
When food is present in the duodenum
20
Q
What functions does CCK have?
A
Bile release
Pancreatic juice release
Delays gastric emptying
Promotes satiety
21
Q
What kind of meals stimulate CCK more?
A
Protein and fat rich foods
22
Q
Where is insulin released from?
A
Beta cells of pancreas
23
Q
When is insulin released?
A
In response to elevated blood glucose
24
Q
What is the role of insulin?
A
To lower blood glucose
Control the storage and release of fatty acids in/out of adipose tissue
25
How does insulin lower blood glucose?
By storing it in liver and muscle tissue as glycogen
26
How does insulin store glucose and fat?
Activates glucose transport into the fat cells by recruiting glucose-transport protein 4 (GLUT4)
Regulating several lipase enzymes
27
What are the metabolic actions of insulin?
Stimulates synthesis of triglycerides from free fatty acids
Inhibits release of free fatty acids from triglycerides
Increases synthesis of liver glycogen
Inhibits gluconeogenesis
Stimulates glucose uptake in skeletal muscle
Reduces hunger
28
What leads to excess amounts of insulin?
Chronic excess energy intake
| Sedentary lifestyle
29
What does increased insulin levels do to lipolysis?
```
Inhibits lipolysis
(so fat isn't broken down from adipose tissue)
```
30
What happens to lipolysis during insulin resistance?
Lipolysis not inhibited
| Leads to visceral fat deposition
31
What happens as visceral fat increases?
Adiponectin production decreases
32
What is adiponectin?
Protein hormone that increases the oxidation of fatty acids
Promotes clearance of excess fat in tissues
Improves insulin sensitivity
33
What implications does increased carbs have on lipolysis and weight?
Increased carbs = increased insulin production = decreased lipolysis/weight gain
34
Which cytokines can adipose tissue increase?
Inflammatory ones
IL-6
TNF-a
35
What is visceral fat a constant source of?
Excess free fatty acids
36
Where do excess free fatty acids go?
Blood to the liver
37
Which two signals does insulin usually send to the liver?
Stop making glucose - inhibit gluconeogenesis
| Store the available blood glucose as glycogen - glycogenesis
38
What happens to the liver/glycogen processes during insulin resistance?
They respond poorly to insulin signals putting patients at risk of chronically elevated glucose levels
39
What liver disease is insulin resistance a major feature of?
Non-Alcoholic Fatty Liver Disease
| NAFLD
40
In which products can high fructose corn syrup be found?
```
Soft drinks
Jams
Cakes
Biscuits
Sauces
```
41
Why should high fructose corn syrup be avoided?
Liver metabolises fructose differently to glucose
| When glycogen stores are full, fructose is converted directly to liver fat
42
Which conditions is excess fructose associated with?
```
NAFLD
Obesity
Hypertension
Excess uric acid levels
Elevated Advanced Glycation End products (AGEs) linked with accelerated ageing and diabetes
```
43
When is ghrelin produced?
When the stomach is empty to stimulate feeding behaviour
44
When is ghrelin suppressed?
After a meal
45
Where is ghrelin produced?
In the stomach
46
Which group has been found to have reduced post-meal ghrelin suppression?
Obese
47
What have ghrelin levels found to do after weight loss?
Increase
| explains why it's harder to keep weight off
48
Which endocrine factors can increase ghrelin levels?
Dysregulated sleep
| Elevated cortisol levels
49
What has been shown to decrease ghrelin secretions?
Exercise
50
What composition of macronutrients has been shown to better at suppressing ghrelin?
High protein
| Moderate carbs
51
What is leptin?
An adipokine produced by white adipose cells in proportion to overall body fat
52
What does increased adiposity do to leptin levels?
Increases leptin
53
What does increased leptin do to appetite?
Suppresses it
54
Why don't elevated leptin levels in overweight people suppress appetite?
Obesity promotes a number of inflammatory processes that weaken leptin signalling
Leads to leptin resistance and failure to suppress appetite
55
What can excess leptin modify?
Insulin sensitivity
Tissue metabolism
Stress responses
Reproductive function
56
What is insulin sensitivity, tissue metabolism, stress responses and reproductive function mediated by?
Hypothalamic-pituitary axis (HPA)
57
Overtime, what does insulin sensitivity, tissue metabolism and stress responses (metabolic changes) lead to?
Abdominal weight gain
Chronic fatigue
Sleep problems
CV distress
58
In what ways can leptin sensitivity be increased?
```
Go gluten free
Reduce sugar consumption
Support gut flora with prebiotics
Reduce inflammation
Regular exercise
Sleep hygiene
```
59
How is the gut flora of overweight individuals different to lean individuals?
Reduced Bifidobacterium
| Increased ratio of Firmicutes vs Bacteroidetes phyla
60
What sort of diet can reduce levels of Bifidobacterium?
High fat diet
61
What have SCFAs been shown to do?
Increase the secretion of appetite-curbing neuropeptides and gut peptides
(support the integrity of the intestinal lining)
62
Example of a gut peptide
GLP-2
63
What is intestinal permeability associated with?
```
Metabolic endotoxemia
(risk factor in obesity)
```
64
What is metabolic endotoxemia characterised by?
Enhanced lipopolysaccharide (LPS) absorption
Low grade chronic inflammation
Insulin resistance
65
What have prebiotics been shown to do?
```
Promote satiety
Reduce hunger
Reduce food ingestion
Suppress ghrelin
Increase peptide YY and GLP-1
```
66
How have probiotics been shown to be successful in metabolic syndrome?
Combination of diet and probiotic supplements (Lactobacilli and Bifidobacteria) effective at lowering blood glucose levels and improving insulin sensitivity compared with diet alone
67
What is appetite?
A psychological reaction that stimulates a physiological response to food
e.g. salivation
68
What is hunger?
A physical reaction that includes chemical changes in the body from a prolonged period without food
69
Why are high fat and high sugar foods more attractive?
Goes back to hunter-gatherer days when these foods offered a survival advantage
Stimulates the dopamine reward system
70
What is the link between obesity and dopamine?
Obese people have been shown to have reduced numbers of dopamine receptors in their brains
Get less of a reward response from eating palatable foods
71
What can the down regulation of dopamine receptors lead to?
Repeated intake of palatable foods
| Risk of overeating
72
What cultural/social factors affect food intake?
```
Religious traditions
Meal patterns
Family traditions
Work lunches/dinners
Attitudes to leaving food on plate
Education
Celebrations
```
73
What sensory factors affect food intake?
```
Appearance/smell of food
Taste of food
Addiction
Packaging/advertising
Surroundings/ambience
Learned likes/dislikes
Flavour fatigue
```
74
What are the emotional factors affecting food intake?
```
Comfort eating
Stress
Insomnia
Loneliness
Sadness
```
75
What factors, other than social, sensory and emotional, can affect food intake?
```
Hormones
Disease states
Medications
Distractions
Climate
Value for money/cost
```
76
What strategies can we use to regulate food intake?
```
Keep blood sugar levels even
Keep track of food
Mindful eating
Focus on adding in rather than taking away
Add more satiating food
```
77
Which is the area in the brain that produces a desire to eat, often as sugar cravings?
Nucleus accumbens
78
How can blood sugar levels be kept stable?
Include protein with every meal
Avoid refined carbs/sugar
Include complex/low GI food
Choose organic/whole foods
79
How can we keep track of food intake?
Be clear on portion sizes
Monitor changes in weight, body fat and waist circumferences
Food diaries
80
How can we practice mindful eating?
```
Prepare in advance what you're eating
Take in the sights, sounds and smells as you prepare
Put away electronics
Sit down, take a deep breath
Be still - silent enjoyment of food
Connect to mind and body
Take in the food with your senses
Listen to your body - sense when you've had enough
```
81
What sort of foods should we be 'adding in'?
```
Nutrient dense
Colourful veg
Fruit
Wholegrains
Pulses
```
82
Which foods should we displace?
Energy dense
High fat
High sugar
High starch
83
Why is filling a client's menu plan with lots of plants better?
Make them feel full
| Increase nutrient without reducing calorie intake
84
What factors can hinder weight loss?
```
Overeating
Junk food
Sedentary lifestyle
High blood sugar
Chronic stress
Poor sleep
Underactive thyroid
Gut flora imbalances
```
85
How can junk food hinder weight loss?
Too many calories from energy dense, nutrient poor foods
86
How can high blood sugar hinder weight loss?
Often associated with high intake of refined carbs and insulin resistance
87
How can chronic stress hinder weight loss?
Chronic stress raises cortisol
Cortisol increases blood sugar
Raised blood sugar increases abdominal fat
88
How can gut flora imbalances hinder weight loss?
Can influence metabolism
89
How can stress be reduced?
Identify and address the cause
Eat to balance blood sugar
Eat diet high in Mg, B vits and C
Reduce reliance on stimulants e.g. coffee and alcohol
Use adaptogenic/nervine herbs such as ashwagandha, chamomile and passionflower
Diaphragmatic breathing to stimulate Vagus nerve
Epsom salts baths - 500g of salts and 10 drops of lavender oil
90
How can we practice good sleep hygiene?
Avoid caffeine
Avoid alcohol
Plan for 8.5-9 hrs in bed
Lights out before 11pm
Ensure bedroom is dark, cool and well ventilated
3 hours before - finish all eating and aerobic exercise
1-2 hours before - minimise exposure to bright lights
Switch of devices
Aim to go to sleep and wake up at the same time each day
91
What are the benefits for HIIT?
Creates an oxygen debt which is repaid via EPOC (excess post-exercise oxygen consumption) whereby oxygen intake increases post exercise
Increased metabolic rate
Decreasing body fat, fasting blood glucose, BP, RHR
Less time spent exercising
92
What are the factors to evaluate when creating a nutritional plan?
Does the plan address behavioural triggers and eating?
Does it provide all necessary macro- and micronutrients?
Is it a diet or lifestyle change?
What is the motivation?
Does it offer education and support?
Does it include exercise?
