Becoming overweight is not an overnight issue
Becoming overweight is not an overnight issue, nor can it be simply attributed to one single cause.
Generally speaking, our metabolism rate starts slowing down upon reaching the age of 25. This triggers two significant changes within our body- an annual muscle loss of 0.5 pounds, as well as a 100 kcal decrease in our daily calorie consumption per decade. At first glance, these numbers may seem petty and insignificant, but in truth, what they infer is rather critical- on average, a person gains 1kg of weight for every 7700 kcal of calorie he accumulates.
Looking into the science of fat accumulation, more than 50% of one’s body fat is deposited immediately beneath the skin (as subcutaneous fat). As a reference point, the average male and female contains approximately 250-280 million and 320-340 million fat cells respectively. In contrast, an obese person may contain up to 635-906 million fat cells, which is alarmingly three times the range of healthy people!
So how does fat grow? The first means is to multiply the number of fat cells, while the second way is to increase the size of existing cells. The former usually happens at the onset of puberty, where fat cells replicate themselves through a cell division process called mitosis. In comparison, the second process occurs after puberty, where fat increases by expanding the size of existing fat cells (they can grow to 4-5 times their normal size). The latter is also equivalent to raising the fat storage capacity of each fat cell, and this can easily lead to a swift increase in a person’s weight as there is a high risk of over- accumulating unwanted fat.