Centrally acting anti-obesity agents

Define overweight in terms of BMI

BMI > 25 kg/ m^2

Define overweight in terms of waist circumference

Men 94-102 cm are high risk

Women 80-88 cm are high risk

Define obese in terms of BMI

BMI > 30 kg/ m^2

Obese I: 30-34.9

Obese II: 35 - 39.9

Obese III: >40

When is surgery considered in obesity?

BMI >40, or BMI= 35-40 with a serious health condition (comorbidity) e.g. T2DM

Define obese in terms of waist circumference (men)

Men > 102 cm waist circumference are very high risk

Define obese in terms of waist circumference (women)

Women > 88 cm waist circumference are very high risk

What fraction of adults aged 45-74 are obese in the UK?

Almost 3/4 of adults aged 45-74 are obese in the UK

Describe prevalence of childhood obesity

For every 1000 10-11 year olds in England,

- 234 are obese

- 143 are overweight

What are the different interventions for overweight and obese patients?

If overweight and low waist circumference:

- Give general advice on healthy weight and lifestyle

If overweight with high/ very high waist circumference OR obese I with low/high/very high waist circumference:

- Diet and physical activity should be recommended

If obese II with low/ high/very high waist circumference OR overweight or obese I with any comorbidities

- Diet, physical activity and drugs should be recommended

If obese II and comorbidities are present:

- Diet. physical activity and drugs should be recommended; surgery should be considered too

What are comorbidities in obesity?

- T2DM

- Hypertension

- CV disease

- Osteoarthritis

- Dyslipidaemia

- Sleep apnoea

What is obesity?

A disorder of homeostatic control of energy balance

Describe how homeostatic control of energy balance is disturbed in obesity

If energy intake is balanced by energy expenditure then body weight and body fat content are typically stable over time (energy homeostasis or balance).

However, in obesity there is an imbalance in energy balance:

- High energy intake: High calorie, energy dense food

( high fat, high sugar)

- Decrease in energy expenditure: Decline in physical activity

( computers, TVs, cars)

This results in excess energy stored in the body as fat

Describe physical activity levels in UK adults

> 6 in 10 adults achieved 150+ minutes of physical activity a week.

Physical activity levels in UK adults vary by sex, location and ethnicity.

Describe CNS regulation of energy homeostasis

1. Meal initiation is caused by several external factors.

2. Meal size is determined by internal factors.

For example, there are nutrients and gut peptides (GLP1, CCK) which indicate how much of a meal should be eaten for meal termination (however this can be over ridden).

3. Once we have eaten a meal, gut peptides (GLP1, CCK) are secreted when food is eaten and signal to the brain that enough has been eaten

4. Nutrients from food are absorbed into the blood stream e.g. glucose and fatty acids which inhibit food intake

5. Stomach stretching (gut distension) sends signals from the vagal nerve which also signals satiety

6. When we eat food, satiety is triggered and inhibits reward pathway (dopaminergic ventral tegmental area and nucleus accumbens) when stopped by satiety signals. Satiety signals then inhibit food intake.

Describe adiposity negative feedback

Adipose tissue releases signals which regulates feeding behaviour.

Leptin is secreted from adipose tissue - the amount secreted is in proportion to fat content in the body.

It reduces food intake in the long term by binding to leptin receptors in the brain.

This enhances the brain's response to satiety signals