Obesity Flashcards
What proportion of people worldwide were living with obesity in 2022? Since 1990, by how much has worldwide adult obesity increased? Since 1990, by how much has adolescent obesity increased?
1 in 8
More than doubled
Quadrupled
How many adults were overweight globally in 2022? Of these, how many were obese? What percentage of adults worldwide were living with obesity in 2022?
2.5 billion / 43%
890 million
16%
How many children under 5 were overweight in 2022? How many children and adolescents aged 5-19 were overweight in 2022? How many children and adolescents aged 5-19 were living with obesity in 2022?
37 million
Over 390 million
160 million
What is obesity defined as?
Excessively high amount of body fat
Generally, what percentage of body fat indicates obesity in men? Generally, what percentage of body fat indicates obesity in women?
Over 25%
More than 30%
What is the formula for Body Mass Index (BMI)? According to BMI, what range is considered normal? According to BMI, what range is considered overweight? According to BMI, what range is considered obese? According to BMI, what value is considered morbid obesity?
Weight (kg) / height (m) ^2
18.5-25
25-30
30-40
40
What does BMI not tell you about fat distribution?
Where the fat is located
How is waist-hip ratio calculated? Is waist-hip ratio or BMI more closely correlated with obesity-related disease? According to the WHO, what waist-hip ratio defines abdominal obesity in males? According to the WHO, what waist-hip ratio defines abdominal obesity in females?
Waist circumference / hip circumference
Waist-hip ratio
Above 0.90
Above 0.85
Why is intra-abdominal fat more harmful than subcutaneous fat?
It is visceral fat (stomach fat deep within the abdominal cavity)
What are other terms for waist-hip obesity?
Central, truncal or andriodal
What problems can obesity lead to?
Pulmonary disease
NAFLD (steatosis, steatohepatitis, cirrhosis)
Gynaecologic abnormalities (abnormal menses, infertility, PCOS, stress incontinence)
Osteoarthritis
Skin
Gout
Premature death
Phlebitis
Cancer (breast, uterus, cervix, colon, oesophagus, pancreas, kidney, prostate)
Cardio/metabolic syndrome (diabetes, dyslipidaemia, hypertension, metabolic syndrome)
GERD
Stroke
Depression
What are symptoms of Metabolic syndrome?
Low HDL, high TAG, hypertension, insulin resistance
What is the result of energy input equaling energy utilized? What is the result of energy input exceeding energy utilized?
No change in body weight
Increase in weight
What type of disorder is obesity?
Metabolic disorder
What causes obesity?
Energy imbalance
What is BMR (basal metabolic rate, body to maintain itself in calories) measured by? What percentage of BMR does skeletal muscle mass account for? Why is BMR lower in women?
Rate of O2 utilisation
20%
Less skeletal muscle mass
What hormone can cause BMR to rise up to 100%? By how much can male sex hormones increase BMR? By how much can growth hormone increase BMR? By how much can sleep decrease BMR?
Thyroid hormone
Up to 15%
Up to 15%
Up to 15%
What impact does malnutrition have on metabolic rate?
Decreased metabolic rate
How does temperature including fever impact BMR?
Increases BMR
What kind of cultural shift has contributed to increased food consumption?
“The supersize culture”
Which factors contribute to increased food availability and consumption?
Reduced food prices, increased fat/sugar
Approximately what percentage of the advised daily calorie intake does a McDonald’s Big Mac hamburger with super size French fries and super size Coke contain?
80%
In which communities are obesity rates greater?
Poorer
Why are humans evolutionarily designed to eat food when it’s available and store it?
Historically food was scarce
What happens to body weight throughout most of adult life?
Remains fairly constant
About how many kilojoules above energy requirements does a person ingest if they gain 20kg (3 stone) over 10 years?
590MJ
Approximately how many kilojoules per day does 590MJ over 10 years equate to?
161kJ (1/5 can of soda (overall 837kJ))
What percentage excess in total energy consumption does 161kJ per day represent?
1.3%
What are the two components to weight regulation?
Hunger varies inversely, metabolism varies directly
What are the symptoms that an Ob/Ob mice showed that indicated that they behaved as starving mice? How did the body fat and weight of the Ob/Ob mice change? Who sequenced the ob gene and characterized its product? What does the ob gene encode?
Unrestrained appetite, elevated cortisol, reduced thermogenesis
5X body fat, 3X weight
Jeffrey Friedman
Leptin
What is leptin? Where is leptin synthesized and secreted from? What is leptin important for?
16kDa peptide
Adipocytes
Long-term control of body weight
What were the effects of injecting leptin into ob/ob mice?
Increased exercise, decreased food, increased thermogenesis
Where does leptin activate neurons? Where are leptin receptors highly expressed? What does leptin affect?
Hypothalamus
Hypothalamus
Metabolism and behaviour
Leptin activates neurones in the hypothalamus which influence the release of what?
Neuropeptides and hormones
What do Neuropeptides modulate? What do GABA, Dopamine, and BDNF modulate? What feeling does Oxytocin evoke?
Feeding behaviour
Behaviour, learning, reward and memory
Satisifaction/satiety
What does Corticotropin-releasing hormone (CRH) released from hypothalamus act on?
Anterior pituitary
Where does ACTH act? What does Thyroid releasing hormone (TRH) released from hypothalamus act on?
Adrenal glands
Anterior pituitary
What does ACTH act on adrenal glands to increase?
Cortisol and hence theromogenesis/BMR
What does TSH increase?
Thyroxine release and BMR
Which nerve carries neuronal and endocrine signals from the gut to the brainstem? Where do signals from the gut act via the blood? Where do signals from the gut act via the blood?
Ascending vagal nerve
Hypothalamus
Where are gut peptide hormones released? What is the effect of gut peptide hormones? Which hormone is released in anticipation of food intake?
GI tract
Promote satiety feeling
Ghrelin (hunger hormone)
What effect does Glucagon have on food intake? How does Glucagon reduce body weight?
Reduces food intake
Reducing food intake and stimulating thermogenesis
What effect does Amylin have on food intake? What effect does Insulin have on satiety? What effect does Insulin have on ghrelin production? What effect does Insulin have on body weight?
Reduces food intake by promoting satiety
Promotes
Reduces ghrelin production
Promotes an increase
How does Insulin promote an increase in body weight?
Promoting glucose storage into fat
Where are short-term feelings of hunger and satiety mediated? Which hormones mediate long-term regulation of body weight?
Gut, stomach, liver, pancreas to the brain
Leptin
What is the risk of a child being overweight if both parents are obese? What is the risk of a child being overweight if one parent is obese? What percentage concordance of obesity is observed in monozygotic twins? What do adoption studies suggest about obesity?
80%
40%
65-70%
Similar stats to twin studies
What does the difference in obesity prevalence between different ethnic groups suggest? What percentage of the variation in weight in the population can be attributed to a variation in genes?
Genetic predisposition
50-70%
What is the general distinction between ‘overweight’ and ‘obese’ based on body fat percentage?
Overweight is less body fat than obese
Besides BMR and conscious physical activity, what other component contributes to daily energy expenditure?
Diet
What do GWAS (Genome-Wide Association Study) studies identify that are associated with increased obesity risk? What is the main conclusion regarding genes and obesity based on the evidence presented?
Polymorphisms in many genes
Genes influence obesity
What is the purpose of a Genome-Wide Association Study (GWAS)? What do GWAS help discover in relation to obesity?
Examination of most genes in individuals
SNPs (single-nucleotide polymorphisms) within genes associated with obesity
What does FTO stand for? In what year were common polymorphisms in FTO found to be associated with obesity? How much more do homozygotes for the FTO polymorphism weigh on average? How much more at risk of obesity are FTO homozygotes?
Fat mass and obesity associated gene
2007
3kg
1.67-fold increased risk
How much heavier are heterozygotes for the FTO polymorphism on average? What percentage of Western Europeans carry the FTO polymorphism? What type of enzyme does the FTO gene encode?
1.2kg
45%
Nucleic acid-demethylase
What is the function of nucleic acid-demethylase? Where is the protein encoded by the FTO gene highly expressed?
Modulates gene expression
Hypothalamus
What is monogenetic obesity caused by? How common is monogenetic obesity as a cause of morbid obesity in children?
A mutation in a single gene
Fairly common
What is the most frequent monogenic cause of morbid obesity in children?
Mutation in one MC4R allele
What is the percentage of morbid obesity cases in children caused by a mutation in one MC4R allele? What is the effect of mutation in one MC4R allele?
> 6%
Haploinsufficiency (loss of function in one copy of genes, when a gene is deleted)
What are the characteristics of the phenotype associated with MC4R mutations?
- Hyperphagia starts at ~ 8 months
- Tendency towards being tall
- Hyperinsulinemia
- Increased bone mineral density
Which type of illnesses can affect weight?
Name a syndrome that can affect weight
What is a type of gland that a tumour can affect weight?
Endocrinopathies
PCOS
Pituitary gland
Name a type of drug that can promote increased appetite
What is a hormone that oral contraceptives contain that could affect weight?
Name a type of medication (other than oral contraceptives) that can affect weight
Corticosteroids
Oestrogen
Anticancer medications
Name a type of psychiatric medication that can affect weight
What is a medication for diabetes that can affect weight?
What is another class of drug that can affect weight?
Lithium
Insulin
Antibiotics
How does gut microbiota influence host metabolism?
Via the metabolites produced during fermentation
What are the two main factors contributing to the obesity epidemic?
- Genetic predisposition
- The obesogenic environment
What are the 3 main treatment options for obesity?
- Diet and Exercise
- Pharmacotherapy
- Bariatric surgery
What is the main challenge with diet and exercise programs for weight loss? What percentage of dieters regain lost weight within two to five years?
Maintaining weight loss
80-95%
What type of drug is Orlistat? How does Orlistat work? What BMI qualifies patients for Orlistat treatment? What waist circumference qualifies men for Orlistat treatment? What waist circumference qualifies women for Orlistat treatment?
Lipase inhibitor
Prevents digestion and absorption of fats
>30kg/m^2
>102cm
>89cm
When should Orlistat therapy be stopped? What is an unpleasant side effect of Orlistat?
If 5% weight loss isn’t achieved after 3 months
Diarrhoea
How do GLP-1R agonists reduce food intake? Where do GLP-1R agonists act directly? What risk is increased in type 2 diabetes patients taking GLP-1R agonists with sulfonylureas or insulin?
Increase satiety
On hypothalamus
Hypoglycaemia
What must patients have to be offered weight management medications according to NICE guidelines? According to NICE guidelines, what is the minimum BMI for weight management medications?
At least one weight-related comorbidity
At least 35kg/m^2
For which ethnic groups is a lower BMI threshold recommended for weight management medications? How much is the BMI threshold usually reduced for specific ethnic groups?
South Asian, Chinese, Black African/Caribbean
2.5mg/m^2
How long until liraglutide effectiveness is determined? How long until semaglutide effectiveness is determined?
After taking it for 3 months
After taking it for 6 months
What percentage of body weight should be lost to determine treatment effectiveness?
At least 5%
What is the maximum duration that GLP-1 receptor agonists can be prescribed for? Why can’t GLP-1 receptor agonists be prescribed indefinitely?
2 years
Weight regains after stopping administration
Where can Wegovy and Saxenda be prescribed in the NHS?
Within a specialist weight management service
Name 3 common bariatric surgeries offered by the NHS
- Gastric band
- Sleeve gastrectomy
- Gastric bypass
How does a gastric band work? How does a sleeve gastrectomy work? How does a gastric bypass work?
- Band around stomach, eat less to feel full
- Some of stomach removed, eat less and feel full
- Joins stomach to small intestine, feel full sooenr
What happens to calorie absorption in a gastric bypass? What is the minimum BMI for bariatric surgery on the NHS? What is the range of BMI required if there’s another health condition?
Do not absorb as many calories
40 or more
35-40
What is a health condition that improves with weight loss for bariatric surgery consideration? What is a further health condition that improves with weight loss for bariatric surgery consideration? What non-surgical measures must have been tried prior to bariatric surgery consideration?
Type 2 diabetes
Hypertension
All appropriate non-surgical measures
What level of fitness is required for bariatric surgery?
Fit enough to have anaesthesia and surgery
What type of management is required as part of bariatric surgery treatment? What commitment is required from the patient after bariatric surgery?
Intensive management
Need for long-term follow-up
What BMI range may consider bariatric surgery for recently diagnosed type 2 diabetes patients? In what circumstances may bariatric surgery be recommended as the first treatment?
30-35
>50 BMI
Which organs and hormones are involved in sending diverse signals related to feeding and metabolism?
- Gut
- Stomach
- Liver
- Pancreas
- Leptin
