Fat storage occurs when calorie intake exceeds calorie output. Although there are other factors that can make us gain weight – including hormones that can affect our metabolism (the rate at which we burn the calories we take in) – usually it comes down to consuming more calories/energy than your body requires in order to function. So if you’re doing less exercise than you might normally, your calorie intake should be reduced, and vice versa. All calories surplus to requirements are then stored in fat cells mostly in our subcutaneous fat just under the skin. Other fat gets stored undesirably around the vital organs.
Obesity is medically defined as having a body mass index (BMI) of over 30 (a healthy person should have a BMI of 18.5 -24.9) and this condition can increase the likelihood of such life-threatening illnesses as heart disease, cancer and osteoarthritis. It is also likely to prompt the development of type 2 diabetes. A reported one in four people in the UK are technically obese.
Why we get hungry
Hunger is a sensation created by hormones across the body, causing you to respond and find food. The hypothalamus situated in the brain is the keen receptor for hunger signals and it will pick up on hormonal secretions, which indicate when the stomach is empty or full. Some cases of obesity are caused by problems with the hypothalamus development.
So once you feel the hunger, how much food do you actually need? Your energy requirements depend on your activity levels, sex, size and stage of life. By not exceeding these calorie intake recommendations you should be able to maintain a healthy weight. (see atricle Do Diets Really Work).