The will to survive

A person with a good mental outlook will need less food than a person with a poor outlook. It can be tempting to give up and resign yourself to die because of a lack of food.

Health, weight, and the amount of food needed to survive

An obese person in good health will need less food to survive than a slim person or a person in poor health. An overweight person can survive on less food, because the body uses stored fat to produce the energy needed to survive.

Water's effect on how much food is needed to survive.

Water is an essential part of determining how much food a person needs to survive. A person can survive up to three weeks without food, or only a little bit of food, as long as he has plenty of water to drink. How much food a person needs to survive is also dependent on the type of food being eaten. Salty or dry food products will cause a person to need more water.

Weather factors

In a cold climate, the body needs more energy to keep warm, which will require more of the body's fat stores to be used. Therefore, a person will require more food to survive in cold weather than someone trying to survive with limited amounts of food in a warm-weather climate.

Medical problems from too little food

While a person does not necessarily need a lot of food to survive, certain medical conditions may arise as a result of a lack of food. Some medical problems consist of irritability, physical weakness, confusion and disorientation. More severe problems associated with starvation are a weakened immune system, low morale, and a sense of lethargy.

Calories matter

The amount of food a person needs to survive is also dependent on the calorie content of the food. Eating high-calorie sweets will keep the belly from growling, but will not keep metabolism going as long as a potato or bread.

Source:

For more in-depth information

Preparing to survive without food

Calories needed to survive

Resource:

72 hour survival kit information