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By logic, a person with a higher quantity of fat would have more calories to burn in the absense of food but the human body can't be simplified to a math formula.

In extreme conditions, can a fat person survive longer than skinny ones?

  • Completely depends on the overall health of the individual, crash diets have killed many obese people, doctors warn against this type of diet especially for the obese. Too many variables. – Moab Aug 17 '11 at 2:17
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When body begin to starve there are three main processes that begin.

  1. General slowdown of metabolism

  2. Destruction of protein to provide glucose for the brain.

  3. Breakdown of triglycerides and using them.

http://archive.unu.edu/unupress/food2/UID07E/UID07E0R.HTM#4.

4. Tissue mobilisation in the obese

A closer examination of the pattern of tissue mobilization during starvation in 'obese' and 'normal' subjects reveals some interesting features. Figure 3 shows the pattern of urinary nitrogen loss during the 31-day fast in a normal weight subject (60.6 kg) studied by BENEDICT (1915) and compares it with an obese subject (154 kg) studied by GILDER et al. (1967) and starved for a comparable period. After the first week, the obese subject lost less fasting urinary nitrogen than the normal weight subject.

This difference in nitrogen loss is further highlighted if we compare the P ratio of normal subjects (Table 1) with that of obese subjects (Table 2). The obese have a lower P ratio and appear to mobilise about 5% of their energy from protein breakdown, in contrast to normal weight subjects, who mobilised approximately 20% of their energy from protein breakdown. It therefore appears that normal weight and obese subjects respond differently during starvation, and that the adipose tissue exerts a profound influence on protein mobilisation.

Although there are no data on P ratio and direct body composition measures in humans, weight and height measured in subjects cited in Tables 1 and 2 were supplemented with single point measurements of BMR and nitrogen loss during fasting on seven more subjects. These values are shown in Figure 4. It can be seen that a close agreement exists between the P ratio and the BMI at the start of the fast. The Figure also shows GARROW's (1983) proposed relationship between BMI and body fat. It is clear from the graph that the P ratio declines in a curvilinear fashion with increasing adiposity. It therefore appears that the tendency to use protein as a fuel in starvation is much lower in the obese than the non-obese human, as has already been suggested by experiments on laboratory animals (HENRY, 1984).

So generally if you have more fat you are able to preserve your proteins for longer so the onset of the degradation of the internal organs is postponed.

  • 5
    which conclusion of course makes perfect sense as the very reason the body stores those fat reserves is to allow it to survive periods when food is scarce. It's a survival instinct which has got out of control in a society where food is never scarce, always abundant, so we keep building up those emergency supplies but never deplete them again. – jwenting Aug 15 '11 at 7:30

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