What Causes Obesity

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It might seem obvious what causes obesity, but there are different possible reasons behind the condition with different routes to treatment. We’re going to take a look at what causes the medically defined condition of obesity.

The simplest and most common answer is taking in more calories than are expended, or eating too much and moving too little.

Calories are units of energy provided by the food we eat, and most adults need between 2,000 to 2,500 calories a day to maintain a healthy weight. If we consume more calories than we need, the extra energy is stored as fat, too much of which can lead to obesity.


Unhealthy diet

A poor diet that includes too much sugar or fat can increase the risk of obesity, as well as just eating too much overall. Other factors relating to diet include:

  • Poor portion control – regularly eating larger amounts of food at mealtimes
  • Eating a lot of processed food – that tends to be higher in fat and sugar
  • Eating out a lot – with takeaways or restaurants you’re likely to eat more at a meal such as having a starter and a dessert
  • Drinking too much alcohol – alcoholic drinks contain a lot of calories
  • Drinking sugary drinks – soft drinks and bottled fruit juices can contain high amounts of sugar and calories


Lack of exercise

Along with eating too much or having a poor diet, not doing enough physical activity can contribute to weight gain.

Getting enough exercise can be tough as many of us work at desks and travel by car, and relax by being sedentary at home in front of the TV.

This can mean you’re not using up the energy you’re taking in from your food, leading to the extra being stored as body fat. This doesn’t mean you have to burn off all 2,000 calories with exercise as most of that energy is naturally used up by your body – and a lot by your brain – during the day, but physical activity is also an essential component.


Medical conditions

Sometimes obesity can’t be easily explained by diet or lack of exercise, and there may be underlying medical conditions that contribute to excess weight.

These conditions can include an underactive thyroid gland, or Cushing’s syndrome, both of which affect hormone production in the body.

There are also some medications that can lead to weight gain, including antidepressants or medicines that treat diabetes and epilepsy.



It can sometimes appear that obesity runs in families, suggesting a genetic predisposition for being overweight. While factors such as metabolism and appetite can be influenced by genetics, traits can also be inherited through upbringing and environment. If your family typically has large meals or a tendency for unhealthy eating habits, these can be passed on and learned by children who may then also grow up to be obese.


Weight loss treatment at Ramsay

Losing weight can be a real challenge, and sometimes it can seem impossible. If you’d like to find out more about the treatments available at your local Ramsay hospital, take a look at our weight loss surgery page, or please get in touch if you’d if you have any questions.

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