Obesity – an introduction

What is obesity?

Obesity is defined as an excessive accumulation of fat that presents a risk to health.  Obesity is a biological, preventable and treatable disease affecting up to 30% of adults in the United Kingdom. It is not a character flaw, a consequence of poor willpower or anyone’s fault.

Body fat is hard to measure directly so the diagnosis of obesity is usually made by measuring body mass index (BMI). This is calculated from your height and weight and although this is an imperfect tool, a BMI of greater than 30kg/m2 is indicative of obesity and a BMI of over 40kg/m2 of severe obesity.


Obesity is a complex disease with several causes that result in more energy (food and drink) coming into the body than being spent through activity and exercise. The excess energy is stored mainly in fat cells that are present throughout the body. Some of the causes include: 

  1. Nutrition: there is growing evidence that not all calories are equal. Certain foods such as refined carbohydrates and unhealthy fats can increase appetite and increase our risk of developing obesity
  2. Societal and community factors:  for example foods high in sugar, fat and salt frequently advertised and marketed and are often cheaper to eat than healthier choices.
  3. Psychological factors:  You are more likely to eat less healthfully during times of stress or if you were feeling down or bored.
  4. Appetite Hormones: Your body has hormones that let you know if you are hungry or full. These do not always work correctly people with obesity
  5.  Not sleeping enough:  People who do not get enough sleep are at greater risk of weight gain than those who do
  6. Genetic factors: Obesity tends to run in families. Our genes determine whether we are more likely to develop obesity or be protected from it
  7. Medications: Some medications such as steroids and antidepressants, for example, can cause weight gain however please do not stop taking medications but speak to your doctor 

In summary, many factors play a role in the development of obesity. Your genes may increase your susceptibility to developing obesity in the right environment.  


What are the risks associated with obesity?

Overweight and obesity are major risk factors for a number of chronic diseases, including type 2 diabetes, cardiovascular diseases and cancer, however not everyone with obesity will develop health problems. The more weight you carry the more likely you are to develop obesity-related conditions. People with severe obesity have the greatest risk of obesity-related health problems.  The good news is as little as 5-10% weight loss can often reduce the effects of these conditions.


Why is it difficult to lose weight and keep it off?

For most people who lose weight keeping the weight off is a struggle. The longer the person is overweight the harder it may be for them to lose weight and keep it off. This is not due to a lack of willpower or effort but is due to biology. Our bodies have evolved in a world where high-calorie food had historically been scarce with undernutrition a constant danger so our bodies are hardwired to protect our weight.

Our metabolism is the amount of energy we use from the food we eat to keep the body functioning. Metabolism varies from person to person, is higher in men and slows with age. As we lose weight our metabolism slows and we burned fewer calories. Our hormones also change when we lose weight in a way that affects our appetite. Weight loss reduces the hormone called leptin, which signals to the brain that we are full, and increases the hormone Ghrelin which is our hunger hormone.




In summary, the reason losing weight is such a struggle is because your efforts are being actively undermined by changes in your body trying to resist weight loss. 



There is a range of treatments available for obesity today but not every treatment will work in every person. The challenge is to find the treatment that will work best for you. We know that the earlier treatment is started the more successful it is likely to be and a combination is often needed to treat obesity.  

  1. Lifestyle changes and dietary modifications: This includes making changes to behaviour to aid weight loss. For example, making healthier food choices, improving sleep, increasing physical activity and addressing emotional factors that may be contributing to weight gain. A registered dietician or an obesity specialist can help advise on an individualised nutritional programme and help support you through your weight loss journey.
  1. Prescription medication: There are a number of approved medicines that can help you lose weight. Please bear in mind that these medications are not suitable for everyone and some of them have side effects.  Medications will not work alone–they can be prescribed as an adjunct to dietary and exercise changes for optimal weight loss.
  2. Weight loss (bariatric) surgery: Some people suffering from severe obesity or from obesity-related health conditions may opt for weight loss surgery to help improve their health. Bariatric surgery is associated with long-term weight loss,  improvement in obesity-related conditions and a reduction in the risk of premature death. However, surgery is not for everyone and comes with risks. 

In summary, obesity is a complex chronic disease with many contributing factors. Managing obesity is about improving your overall health not just about losing weight. Your doctor can guide you through the treatment options but the mainstay of treatment will always be dietary and lifestyle changes that are healthy, sustainable and individualised. Some people will also benefit from medication or surgery.


By Dr Mohgah Elsheikh