Survival on Limited Food Supply: The Role of Body Fat
When faced with a limited food supply, how does body fat affect survival chances? This article examines the physiological basis of fat stores and their role in survival during periods of starvation.
The Energy of Body Fat
Body fat stores nine calories per gram, which is a valuable energy reserve that the body taps into when more accessible food sources are depleted. This is a critical survival mechanism that allows organisms to survive for extended periods without food.
Survival Duration Without Food
A person can survive for days without water, but weeks without food. The body’s primary energy source is carbohydrates, stored in the liver and muscles, which are depleted in just a couple of days. After these stores are exhausted, the body begins to break down muscle and fat stores for energy. The more body fat a person has, the longer they can survive before muscle depletion becomes significant.
Real-life Experience
A personal experience illustrates the importance of body fat during times of starvation. When the author was 24 and became ill, they were isolated with no access to medical care, food, or money. Starting at nearly 300 lbs, they lost over 130 lbs during a 2-week period when food and water intake were extremely limited. Had they been a healthier weight, the reduced fat stores likely would have resulted in a much shorter survival time.
Adipose Tissue and Survival During Starvation
The primary purpose of storing adipose tissue (body fat) is to maintain energy reserves during starvation. During a starvation state, the body utilizes fat stores, circulating free fatty acids, and entering a state of ketosis to provide energy to cells. The brain also gets glucose from the process of gluconeogenesis.
However, if the starvation period is prolonged, the body resorts to breaking down muscle tissues to produce glucose. Cellular and muscular atrophy, particularly in vital organs like the heart, can lead to death. Therefore, while being fatter generally provides a survival advantage, the advantage diminishes with prolonged starvation as the body needs not only energy but also protein and essential vitamins and minerals to sustain cellular and tissue structure.
Concerning obesity and its health issues, individuals with obesity may have additional health problems such as diabetes and high blood pressure, which can complicate survival during starvation. These conditions can further reduce the survivability of an obese person depending on the severity and the duration of the starvation period.