In the past people were dependent on the skills of the hunter, the knowledge of the gatherers to find edible roots, berries, mushrooms and other vegetation and most of all they depended on nature to provide a suitable climate for fruits and vegetables to grow.
When famine strikes, food is in short supply and survival depends on stored fat deposits in the body. Fat cells are found mostly underneath the skin and the concentration of the extra storage areas depends on your gender. Men tend to carry extra body fat in the chest area and the midsection giving the appearance of an apple shape.
Women are more likely to accumulate body fat in the breast area, waist, hips and buttocks creating the appearance of a pear-shape
The function of fat cells is to provide protection and energy when food is in short supply. Our bodies are always using energy, even when we sleep and this energy is supplied by the foods we eat or from the reserves in the fat cells.
When food is available again, these depleted storage areas or fat cells are then ready to fill up again, preparing for the next starvation cycle or famine and the cycle continues.
This explains why it is almost impossible to lose weight and to keep it off. The body is seeing weight loss as a threat to survival and is trying to prepare for the next famine or food shortage and with every new attempt to lose weight the fat cells are getting bigger and more efficient to store additional reserves.