Why is obesity so widely prevalent?

• In simplistic terms, people gain weight due to calories in > calories out, however there is increasing evidence of implicated genes
• In an evolutionary context being able to optimise response to feeding opportunities was an advantage ('thrifty genotype'), however this is maladaptive in today's environment
• A subset of the population may have a stronger 'thifty genotype' and therefore be more susceptible to put on weight
• One of the phenotypic expressions of the thrifty genotype is insulin resistance
• Leptin communicates fat stores - decreases when fat stores decrease

  • However if you have plenty of fat stores, leptin doesn't do the opposite

    

Population sub-groups at risk of obesity

• Socio-economic deprivation

• Children at risk of obesity, or parents with obesity

• Rapid weight gain

• Post-obesity

• Pregnancy

• Smoking quitting

• Physically inactive (including due to disabilities)

• Ethnic groups

• Genetic markers of susceptibility

The impact of obesity on health

• Obesity is associated with an increased risk of developing a number of chronic diseases/conditions, including T2DM, coronary heart disease, hypertension and stroke
• Also associated with common mental health problems
• Co-morbidities which relate to increased fat mass include osteoarthritis, back pain, sleep apnoea and asthma
• Most complications can be reduced by weight loss

Obesity and COVID-19

• Obese patients will store fat in their liver and skeletal muscle, where it will disturb metabolism
• This leads to very high levels of insulin in the blood, which is associated with other disturbances including an increase in inflammatory cytokines and a decrease in adiponectin, which directly protects the lungs

Factors to consider in weight management

'Drivers' of obesity

• Energy-dense food and drinks
  • A high proportion of calories, fats and sugars come from discretionary food and drinks e.g. cakes, sugary drinks
• Increased portion sizes