Taking in more energy (food) than what is needed for your day to day activity.
Choosing foods that are high in fats and refined sugars (commonly referred to as ‘junk foods’).
Inadequate physical exercise.
It is easy to get used to all or some of the above without realisation. Fat content and excess carbohydrate of the food will be stored in the fat cells if the daily intake is in excess of the daily bodily needs.
What are junk foods and how do they affect weight?
Normally a hormone called ‘leptin’ makes us loose appetite when the level of body fat and hence stored calories exceeds a certain threshold. After a regular high fat diet, unfortunately the human body and the appetite centre in the brain become used to, in other words resistant, to this hormone. As a result, the threshold for appetite becomes higher, we feel more hungry and hence eat more.
Additionally regular use of refined sugary foods leads to a rapid rise in the level of glucose after the meal. This leads to excess production and release of another hormone called ‘insulin’. This hormone keeps the blood sugar in the normal range. When a lot of insulin is needed persistently to keep this balance, the human body develops resistance and that changes the way in which we metabolize sugars and fat. Excess insulin increases the storage of fat in the body.
What is the relationship of weight to physical activity?
The body needs a regular supply of energy for the maintenance of its normal functions. If the food supplies more energy than is needed, there is a net surplus which is stored as fat. As a result the fat cells increase both in number and size and as a result we become obese. Modern amenities at home, at work, in travel, an increasingly rich variety of food and cold weather mean that energy surplus is easily reached unless we take extra exercise. Unfortunately at present less than 1 in 5 people in the UK take extra exercise.
Am I genetically at an increased risk of obesity?
We can inherit a predisposition to obesity, but these genes do not make one obese. Anybody with a family history of obesity is likely to be obese themselves only if she/he follows the same lifestyle as other family members. In other words even if you are born into a family where many members are overweight, your weight will be determined by your own lifestyle.
If your life style is similar to other overweight people in your family, then that combined with your genetic susceptibility would mean that you will also gain weight like them. On the other hand, by adopting a different life style, you can avoid becoming overweight or obese.
Why is weight loss difficult to maintain?
It is often difficult to break the habit of excess food intake.
As explained above, excess caloric intake over a long term
raises the threshold at which ‘leptin’ is released
the body becomes unresponsive to leptin
the hormone is not transported to the appetite centre in the brain.
Under these circumstances the body loses it ability to control appetite and as a result the weight.
Paradoxically, a decrease in calorie intake often lowers the metabolic rate i.e. the number of calories that you use per day for the routine functions. As a result the surplus is reached easily and more calories are stored as fat.
Wrong type of exercise / diet: Some diets for weight reduction restrict carbohydrate or fat intake. Long-term use of such unbalanced diets results in malnutrition.